[{"title":"SANE-000: Standard Template & Style Guide","url":"https://sane-av.github.io/standards/sane-000-example/","type":"Standard","snippet":"An example standard demonstrating the required structure, frontmatter, and writing conventions for all SANE standards documents. Use this as a template when drafting new standards.","tags":["meta","template","example","draft"],"text":"> **Note:** This document is a template. It contains structural guidance in [bracketed italics] and [Required]/[Optional] annotations on section headings. Remove these annotations when writing a real standard. Refer to the [SANE conventions](https://sane-av.github.io/contributing) for shared requirement language and process rules.\n\n---\n\n## 1. Standard at a Glance [Required]\n\n*Use this section as the quick-reference page for the standard. It should help a reader understand the basic idea of the standard without reading the entire document first. Keep it short, practical, and easy to scan. Do not use this section for deep explanation, edge cases, long examples, or background theory — those belong later in the document.*\n\n### 1.1 What This Standard Is About [Required]\n\n*Briefly explain what the standard controls. Write in plain language. Good pattern: \"This standard defines how [subject] should be [labeled / documented / measured / installed / configured / verified] in professional AV systems.\" One short paragraph is usually sufficient.*\n\nThis standard defines how [subject] should be [action] in professional AV systems.\n\n### 1.2 Why It Matters [Required]\n\n*Briefly explain the practical problem this standard solves. Focus on real AV work: design clarity, installation consistency, commissioning, troubleshooting, service, owner handoff, safety, interoperability, or long-term maintenance. Good pattern: \"This standard exists so that [reader or role] can [do useful thing] without [common problem].\" One short paragraph is usually sufficient.*\n\nThis standard exists so that [reader or role] can [do useful thing] without [common problem].\n\n### 1.3 Core Rules [Required]\n\n*List the most important requirements from the body of the standard. This is a summary, not a replacement for the full requirements section. Each item should be short enough to scan quickly. Use MUST, MUST NOT, SHOULD, SHOULD NOT, or MAY only when the same requirement is fully defined later in the document. Recommended length: 3 to 7 items.*\n\n- [First core rule]\n- [Second core rule]\n- [Third core rule]\n\n### 1.4 Compliance Snapshot [Required]\n\n*Summarize how someone can tell whether the standard was followed. This should not introduce new requirements — it should point back to the compliance section later in the document. Address: what must be present, what must match, what must be verified, what must be documented, what would clearly fail.*\n\n- What must be present: [brief]\n- What must match: [brief]\n- What must be verified: [brief]\n- What must be documented: [brief]\n- What would clearly fail: [brief]\n\n### 1.5 Where to Go Next [Required]\n\n*Guide different readers to the parts of the standard they are most likely to need. Only include roles relevant to the specific standard.*\n\n> **Template note:** When writing real standards, prefer descriptive references (e.g., \"the Compliance section\") over specific section numbers. Section numbers may shift during revision, and descriptive references are less likely to go stale.\n\n- **Designers** should review Sections [X] and [Y].\n- **Installers** should review Sections [X] and [Y].\n- **Programmers** should review Sections [X] and [Y].\n- **Commissioning agents** should review Sections [X] and [Y].\n- **Service technicians** should review Sections [X] and [Y].\n\n---\n\n## 2. Purpose [Required]\n\n*Explain why the standard exists. The purpose should describe the problem being solved and the outcome the standard is trying to create. Keep this section focused — do not put detailed requirements here. Good pattern: \"This standard defines [subject] for use in professional AV system design, installation, documentation, commissioning, and long-term support. The purpose of this standard is to reduce [ambiguity / inconsistency / rework / service difficulty / safety risk / coordination problems] by establishing [clear requirement or convention].\"*\n\nThis standard defines [subject] for use in professional AV system design, installation, documentation, commissioning, and long-term support.\n\nThe purpose of this standard is to reduce [problem] by establishing [solution].\n\n---\n\n## 3. Scope [Required]\n\n*Define the boundaries of the standard. The reader should understand what the standard applies to and what it does not apply to.*\n\n### 3.1 In Scope [Required]\n\n*List the systems, documents, equipment types, project phases, workflows, or conditions covered by the standard. May include: covered system types, document types, project phases, physical conditions, signal types, user roles, verification activities.*\n\n- [Covered system type]\n- [Covered project phase]\n- [Covered activity or condition]\n\n### 3.2 Out of Scope [Required]\n\n*List related topics that are not covered by this standard. This is important because many AV topics overlap. May include: topics handled by another SANE standard, topics governed by code/law/authority having jurisdiction, manufacturer-specific procedures, owner-specific requirements, design choices intentionally left flexible. If another standard covers an excluded topic, reference it here.*\n\n- [Excluded topic]\n- [Excluded topic] — handled by SANE-[XXX] if applicable.\n\n---\n\n## 4. Audience [Required]\n\n*Identify who the standard is written for. A SANE standard should be readable by the people who need to create, review, install, commission, service, or maintain the work. Include only the roles that are relevant to the specific standard.*\n\nPossible audiences include: AV designers, AV engineers, installers, rack fabricators, DSP programmers, control system programmers, commissioning agents, service technicians, project managers, owners and operators, IT/network teams, architects and electrical engineers, and reviewers responsible for project acceptance.\n\n---\n\n## 5. Definitions [Required]\n\n*Define terms that are necessary to understand the standard. Only define terms that are used in a specific way in this document. Do not define common AV terms unless the definition matters to the standard. Format: **Term Name** — Definition of the term as it is used in this standard. If a term is defined by an external standard, cite that source in the references section.*\n\n**Term Name** — Definition of the term as it is used in this standard.\n\n**Another Term** — Another definition. As defined in [external standard].\n\n---\n\n## 6. Requirement Language [Required]\n\n*This standard uses the key words defined in the SANE conventions document for expressing requirement levels. A summary is provided below; the canonical definitions are maintained in the [SANE conventions](https://sane-av.github.io/contributing).*\n\n**MUST** — The requirement is mandatory for compliance.\n\n**MUST NOT** — The item is prohibited.\n\n**SHOULD** — The item is strongly recommended, but exceptions may exist with documented justification.\n\n**SHOULD NOT** — The item is discouraged, but exceptions may exist with documented justification.\n\n**MAY** — The item is optional.\n\nOnly use MUST for requirements that can be verified by review, inspection, measurement, testing, or documentation.\n\n---\n\n## 7. Requirements [Required]\n\n*This is the main body of the standard. Each requirement should be: clear, numbered, testable, specific enough to implement, and written so a third party can verify it. Avoid vague requirements like \"use best practices\" or \"ensure good performance\" — instead, define what \"clear,\" \"good,\" or \"complete\" means.*\n\n### 7.1 General Requirements [Required]\n\n*Requirements that apply broadly across the standard.*\n\n1. [First general requirement.]\n2. [Second general requirement.]\n\n### 7.2 Format Requirements [Optional]\n\n*Use this section when the standard defines a required structure, naming convention, drawing convention, table format, label format, file format, signal format, or other repeatable pattern. Tables are often useful here.*\n\n| Element | Format | Example |\n|---------|--------|---------|\n| [Element name] | [Format specification] | [Example value] |\n\n### 7.3 Documentation Requirements [Optional]\n\n*Information that must appear in drawings, schedules, configuration files, reports, labels, handoff documents, or other project records. Remove this section if the standard does not impose documentation requirements.*\n\n1. [First documentation requirement.]\n2. [Second documentation requirement.]\n\n### 7.4 Installation or Implementation Requirements [Optional]\n\n*Requirements that affect physical installation, configuration, programming, commissioning, or deployment. Remove this section if the standard does not cover installation or implementation.*\n\n1. [First installation requirement.]\n2. [Second installation requirement.]\n\n### 7.5 Prohibited Practices [Optional]\n\n*Things that are not allowed because they create ambiguity, inconsistency, unsafe conditions, service difficulty, or project risk. A prohibited practice should use MUST NOT. Remove this section if no practices are prohibited.*\n\n1. [First prohibition — use MUST NOT.]\n2. [Second prohibition — use MUST NOT.]\n\n### 7.6 Recommended Practices [Optional]\n\n*Practices that are strongly recommended but not mandatory. Use SHOULD. Do not put optional advice here if it has no real effect on the success of the work. Remove this section if no practices are recommended beyond the requirements above.*\n\n1. [First recommendation — use SHOULD.]\n2. [Second recommendation — use SHOULD.]\n\n---\n\n## 8. Compliance [Required]\n\n*Define what it means to claim compliance with the standard. Compliance should be objective. A reviewer should be able to determine whether the standard was followed without guessing the author's intent.*\n\n### 8.1 Compliance Requirements [Required]\n\n*List the conditions that must be satisfied for compliance. These should reference requirements from Section 7 rather than introduce new rules.*\n\nAn installation, document, or deliverable claiming compliance with this standard shall:\n\n1. [Compliance condition referencing a requirement from Section 7.]\n2. [Compliance condition referencing a requirement from Section 7.]\n\n### 8.2 Compliance Evidence [Optional]\n\n*List the types of evidence that can be used to verify compliance. Possible evidence may include: drawings, equipment schedules, cable schedules, rack elevations, photographs, configuration files, DSP files, control system files, network configuration records, test results, commissioning reports, handoff documentation. Include only evidence types relevant to the specific standard. Remove this section if evidence requirements are covered by the compliance requirements above.*\n\n- [Evidence type 1]\n- [Evidence type 2]\n\n### 8.3 Non-Compliance [Optional]\n\n*Describe the kinds of failures that would make an implementation non-compliant. This section should help reviewers, installers, and project teams recognize common failure modes. Remove this section if non-compliance is self-evident from the requirements.*\n\n1. [Common failure mode 1]\n2. [Common failure mode 2]\n\n---\n\n## 9. Examples [Optional]\n\n*Show how the standard works in practice. Examples should support the requirements — they should not replace the requirements. Possible example types include: compliant example, non-compliant example, borderline example, drawing example, label example, table example, configuration example, field condition example, exception example. Each example should explain why it passes or fails. If examples would make the standard confusing or artificially specific, keep them minimal and place extended examples in Appendix A. Remove this section if examples are not needed.*\n\n### Example: [Compliant scenario]\n\n[Description of the scenario and why it passes.]\n\n### Example: [Non-compliant scenario]\n\n[Description of the scenario and why it fails.]\n\n---\n\n## 10. Field Notes [Optional]\n\n*Practical guidance that helps people apply the standard in real AV work. This section may include lessons from design, installation, commissioning, service, ownership, or long-term maintenance. Field notes are useful for explaining how the standard is likely to fail in real life. May cover: common mistakes, coordination issues, service implications, handoff issues, retrofit concerns, owner-furnished equipment, legacy systems, multi-phase projects, differences between drawings and field conditions. Field notes are not mandatory unless they use requirement language such as MUST or SHOULD. Remove this section if no field notes are needed.*\n\n- **[Topic]:** [Practical observation or lesson.]\n- **[Topic]:** [Practical observation or lesson.]\n\n---\n\n## 11. Exceptions [Optional]\n\n*Explain how exceptions are handled. Exceptions should be allowed, but they should be documented. A documented exception should include: the requirement being excepted, the reason for the exception, the alternate method used, the person/role/authority approving the exception, the date of approval. Exceptions should not be used to avoid safety, code compliance, testing, documentation, or owner requirements. Remove this section if exceptions are not applicable.*\n\nTo request an exception from this standard:\n\n1. [Document the requirement being excepted.]\n2. [Document the reason for the exception and the alternate method used.]\n\n---\n\n## 12. Relationship to Other Standards [Required]\n\n*Explain how this standard relates to other standards, requirements, or authorities. May include: other SANE standards, public standards, manufacturer documentation, project specifications, codes and regulations, owner standards, contract documents.*\n\n- This standard extends / complements / is independent of SANE-[XXX].\n- [Relationship to another standard, code, or authority.]\n\nWhen this standard conflicts with law, code, contract requirements, manufacturer requirements, or an authority having jurisdiction, the higher authority governs.\n\n---\n\n## 13. References [Required]\n\n*List sources used by the standard. Separate references into normative and informative when appropriate.*\n\n### 13.1 Normative References [Optional]\n\n*Normative references are required to apply the standard. Use this section for external standards, codes, or documents that the reader must follow in order to comply. Remove this section if there are no normative references.*\n\n- [Standard Number]: [Standard Title]\n- [Standard Number]: [Standard Title]\n\n### 13.2 Informative References [Optional]\n\n*Informative references provide background, examples, supporting information, or related reading. Use this section for sources that help explain the standard but are not required for compliance. Remove this section if there are no informative references.*\n\n- [Source title or description]\n- [Source title or description]\n\n---\n\n## Appendix A: Extended Guidance [Optional]\n\n*Deeper guidance that is useful but not necessary for the quick understanding of the standard. May include: extended explanation, extended examples, edge cases, legacy-system guidance, migration guidance, manufacturer-specific considerations, owner handoff guidance, review procedures. Remove this appendix if not needed.*\n\n---\n\n## Appendix B: Rationale [Optional]\n\n*Explain why the standard was written the way it was. The body of the standard should define what is required; the rationale should explain why those requirements exist. Good content includes: design reasoning, tradeoffs, history, prior art, problems the standard is trying to prevent, why stricter or looser requirements were not chosen. Remove this appendix if not needed.*\n\n---\n\n## Appendix C: Revision History [Optional]\n\n*Track published-version changes here. The canonical revision history is the git log for this repository; this appendix provides a human-readable summary for stable releases only. Remove this appendix for draft standards.*\n\n| Version | Date | Notes |\n|---------|------|-------|\n| 0.1 | YYYY-MM-DD | Initial draft. |"},{"title":"The Case for Open AV Standards","url":"https://sane-av.github.io/blog/case-for-open-av-standards/","type":"Blog","snippet":"A technical and economic argument for why the professional AV industry should adopt openly published, freely implementable standards.","tags":["standards","open source","industry policy","economics"],"text":"## Abstract\n\nThis paper argues that the professional audiovisual industry would benefit significantly\nfrom a transition to openly published, freely implementable technical standards. We examine\nthe economic incentives that produced the current closed-standards ecosystem, the costs\nthose incentives impose on practitioners and end users, and the precedents from adjacent\nindustries that demonstrate the viability of open-standards models.\n\n## 1. Background\n\nThe professional AV industry currently relies primarily on standards developed and\nadministered by membership-based organizations. Access to the underlying specifications\ntypically requires either organizational membership or per-document purchase fees.\n\nThis model was inherited from earlier industrial standards bodies and made sense in a\npre-internet era when the cost of distributing physical documents was non-trivial. That\nconstraint no longer exists. The marginal cost of distributing a standards document online\nis effectively zero.\n\nDespite this, the access model has remained largely unchanged.\n\n## 2. Economic Analysis\n\n### 2.1 Direct Costs\n\nThe most visible cost is the direct financial burden of membership fees and document purchase\nprices. For large firms, these are rounding errors in the cost structure. For small independent\nintegrators, they represent meaningful overhead.\n\nThis creates a market structure that favors consolidation: larger firms can access and comply\nwith standards at lower marginal cost, providing a structural competitive advantage over\nsmaller operators who provide the same services.\n\n### 2.2 Education and Training Costs\n\nVocational training programs face a particular challenge. Teaching students to comply with\nindustry standards requires access to those standards - but educational institutions often\nlack the budget for full organizational membership.\n\nThe result is a classroom-to-industry gap: graduates who have learned about standards in\ntheory but have never read the actual specifications they're expected to implement.\n\n### 2.3 Innovation Costs\n\nClosed standards create moats. When the cost of entry to an interoperability ecosystem\nincludes membership fees, smaller innovators are excluded from the conversation that\ndefines the ecosystem.\n\nOpen standards lower this barrier, enabling more competitors to build interoperable products.\nMore competition in a well-defined interoperability space tends to drive up quality and\ndrive down prices - outcomes that benefit the end users of AV systems.\n\n## 3. Precedents\n\n### 3.1 The Internet Engineering Task Force (IETF)\n\nThe IETF has produced the core protocols of the internet - TCP, IP, HTTP, SMTP, DNS -\nthrough an open process. All RFCs are freely available. Anyone can participate in the\nprocess. The result is a remarkably robust and interoperable global network built by\nthousands of competing vendors.\n\n### 3.2 The World Wide Web Consortium (W3C)\n\nHTML, CSS, and the DOM are W3C standards, developed through an open multi-stakeholder\nprocess and freely available. The web would not exist in its current form under a\nclosed-standards model.\n\n### 3.3 IEEE 802\n\nThe IEEE 802 family (Ethernet, WiFi) demonstrates that even hardware-level standards\ncan be open while generating enormous commercial ecosystems. 802.11 WiFi chips are\ncommodities; the open standard enabled rather than prevented the commercial success\nof hundreds of manufacturers.\n\n## 4. A Path Forward\n\nWe do not argue that existing standards organizations should be disbanded or that their\nwork has no value. Much of it is valuable. What we argue is that the access model should\nchange - and that the industry should additionally develop new standards in the open\nfor areas currently lacking adequate coverage.\n\nThe model we propose, and that SANE implements:\n\n1. **Open access**: All standards freely available online, no membership required\n2. **Open process**: Proposals, discussions, and ratification in public view\n3. **Version control**: Full history of all changes, auditable by anyone\n4. **No IP encumbrances**: All standards freely implementable without patent licensing\n5. **Community governance**: Standards are owned by the community, not a corporation\n\n## 5. Conclusion\n\nThe professional AV industry is a mature technical discipline with a rich body of practical\nknowledge. That knowledge belongs to the people who built it - the engineers, integrators,\nand technicians who design and deploy AV systems every day. SANE exists to make that\nknowledge freely accessible to everyone in the field, and to those who will enter it.\n\nThe technology to do this has existed for decades. The question is whether the industry has\nthe will to use it. We believe it does.\n\n---\n\n*This paper is published under CC BY-SA 4.0. To suggest additions or corrections, open an issue\non [GitHub](https://github.com/sane-av/sane-av.github.io).*"},{"title":"Welcome to SANE","url":"https://sane-av.github.io/blog/welcome-to-sane/","type":"Blog","snippet":"Introducing the Society for AV Norms & Engineering - an open source alternative to proprietary AV standards bodies.","tags":["announcement","open source","community"],"text":"The AV industry has a standards problem.\n\nToday, the technical specifications that govern how we design, install, and operate professional\naudiovisual systems are largely locked behind membership fees and paywalls. Want to read the\nstandard that tells you how to certify an AV technician? Pay up. Want to reference the official\nrecommendation for audio signal levels in a commercial installation? Join the organization first.\n\nWe believe this is wrong. And we're doing something about it.\n\n## What is SANE?\n\nSANE - the **Society for AV Norms & Engineering** - is a community-driven organization that\ncreates free, open, and transparent standards for professional AV systems. We operate like the\nIETF or W3C: all our work happens in the open, all our documents are freely accessible, and\nanyone can contribute.\n\nOur standards are published under [Creative Commons CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0/).\nThat means you can read them, implement them, share them, and build on them - for free, forever,\nwith attribution.\n\n## What we're building\n\n- **SANE Standards** - Technical specifications for audio levels, video signal standards,\n  control protocols, cabling, and more\n- **AV Glossary** - Plain-language definitions for the entire AV vocabulary\n- **Equipment Database** - Open, community-maintained spec data for real-world AV gear\n- **Engineering Tools** - Free calculators for throw ratios, dB levels, room modes, and more\n  - **Blog** - In-depth technical writing on AV design and engineering\n\n## How to get involved\n\nEverything lives on [GitHub](https://github.com/sane-av/sane-av.github.io). You can:\n\n- **Propose a standard** by opening an RFC issue\n- **Improve the glossary** by submitting a PR\n- **Add equipment data** to the open database\n- **Write a blog post** or whitepaper\n- **Build a tool** - all calculators are plain client-side JS\n\nThis is day one. The first standards are in draft. The glossary has a handful of entries.\nThe equipment database is nearly empty. We need your expertise, your time, and your voice.\n\nWelcome to SANE. Let's fix AV standards together."},{"title":"Why Open AV Standards Matter","url":"https://sane-av.github.io/blog/why-open-av-standards-matter/","type":"Blog","snippet":"The case for treating AV standards like open source software - and what the industry loses when they're locked away.","tags":["standards","open source","industry"],"text":"Open standards are not a radical idea. The entire internet runs on them.\n\nHTTP, TCP/IP, HTML, CSS, WebRTC - these technologies power billions of dollars in economic\nactivity and they're all built on openly published, freely implementable specifications.\nAnyone can read them. Anyone can build with them. Anyone can propose improvements.\n\nThe professional AV industry has largely gone in the opposite direction.\n\n## The Cost of Closed Standards\n\nWhen standards are paywalled, the costs are distributed unevenly:\n\n**Small integrators pay twice.** They pay membership fees to access the standards that govern\nthe work they're already doing. These fees are a rounding error for large firms and a genuine\nburden for small shops.\n\n**Manufacturers optimize for certification, not quality.** When the standards body is also the\ncertifier, there's a structural incentive to make certification achievable over making products\ngenuinely better.\n\n**Innovation slows.** Open standards enable interoperability. Closed standards create moats.\nAn open ecosystem where Manufacturer A's DSP talks natively to Manufacturer B's control system\nbenefits integrators, end users, and ultimately the manufacturers who build the best products.\n\n**Education suffers.** You can't teach to a standard your students can't access. This creates\na permanent classroom-to-industry gap for the next generation of AV professionals.\n\n## What Open Standards Enable\n\nLook at what open standards did for adjacent industries:\n\n- **Networking**: 802.11 (WiFi), 802.3 (Ethernet) - open IEEE standards drove an explosion\n  of competing implementations and drove costs to near-zero\n- **Web**: HTML and CSS from the W3C enabled every website you've ever visited\n- **VoIP**: SIP and RTP from the IETF enabled an entire industry of open-source telephone systems\n\nThe AV industry could have the same thing. DSP configuration formats. Room correction data\nschemas. Control protocol specifications. Installer certification competency frameworks.\nAll of it could be open, versioned, community-maintained, and free.\n\n## SANE's Approach\n\nWe're not trying to replace every existing standard. Some existing specifications are well-\nengineered and widely adopted. Where they exist, we'll reference them.\n\nWhat we're building is the layer that's missing: a community home for the standards that\n*should* exist but don't, and for the standards that exist but shouldn't be locked behind\na paywall.\n\nWe operate by rough consensus in the open. Every proposal, every change, every vote is\nvisible on GitHub. If you disagree, fork it. If we're wrong, tell us in an issue.\n\nThat's how standards should work."},{"title":"1/3 octave equalizer","url":"https://sane-av.github.io/glossary/13-octave-equalizer/","type":"Glossary","snippet":"An audio equalizer that provides 30 or 31 slider adjustments corresponding to specific fixed frequencies with fixed bandwidths, with the frequencies centered at every one-third of an octave. The adjustment points shape the overall frequency response of the system.","tags":["Audio"],"text":"A **1/3 octave equalizer** is a graphic equalizer that divides the audible frequency spectrum into 30 or 31 bands, each centered one-third of an octave apart, with a fixed center frequency and fixed bandwidth per band. A single slider controls the boost or cut at each center frequency, allowing the operator to shape the overall frequency response of an audio system. It is the standard equalization tool for professional sound reinforcement system tuning.[^1]\n\n## How It Works\n\nThe audible frequency range spans roughly 20 Hz to 20 kHz - approximately 10 octaves. Dividing each octave into thirds produces 30 bands (20 Hz to 16 kHz) or 31 bands when a band centered on 20 kHz is added. The center frequencies follow ISO 266, the international standard for preferred frequencies (e.g., 25 Hz, 31.5 Hz, 40 Hz, 50 Hz, 63 Hz ... 16 kHz, 20 kHz).[^2]\n\nEach band implements a second-order filter with a constant **Q** (quality factor) of approximately 4.3 at the -3 dB points, giving a bandwidth of exactly one-third of an octave regardless of center frequency.[^3] Adjacent bands overlap, so adjustments interact with neighboring bands.\n\nThe term *graphic* refers to the visual representation created by the slider positions - the sliders form a curve that approximates the frequency response being applied, making the setting immediately readable at a glance.[^1]\n\n## History\n\nThe first true graphic equalizer was the Cinema Engineering type 7080, an active tube device developed in the **1950s** by Art Davis. It featured six bands, each 1.5 octaves wide, with an 8 dB boost/cut range using slide switches.[^4]\n\nDavis followed this in **1961** with the Langevin EQ-252-A (seven sliders), then reworked it for Altec Lansing as the Model 9062A EQ, which sold well into the 1970s.[^4] In **1967**, Davis developed the first 1/3 octave variable notch filter set - the Altec-Lansing \"Acousta-Voice\" system - establishing 1/3 octave spacing as the professional standard for room correction.[^5]\n\nThe 1/3 octave resolution became dominant in professional AV because it aligns with the ISO octave band standard used in acoustic measurement instrumentation, allowing direct comparison between measured room response and applied EQ correction.[^2]\n\n## Common Uses in AV\n\n- **System equalization:** Correcting room resonances and modal anomalies identified during acoustic measurement with a real-time analyzer (RTA)\n- **Feedback suppression:** Attenuating frequencies that are prone to ringing in a speech reinforcement system\n- **House curve:** Applying a gentle bass-shelf boost to compensate for the psychoacoustic loss of bass perception at lower listening levels\n- **Loudspeaker alignment:** Compensating for driver response deviations identified on a manufacturer's frequency response plot\n\n## 1/3 Octave vs. Parametric Equalizer\n\n| Feature | 1/3 Octave Graphic | Parametric |\n|---|---|---|\n| Center frequencies | Fixed (ISO 266) | Fully adjustable |\n| Bandwidth (Q) | Fixed (~4.3) | Adjustable |\n| Bands | 30 or 31 | Typically 4-8 |\n| Visual feedback | Yes (slider positions) | No |\n| Surgical precision | Limited | High |\n| Typical use | Room EQ, system tuning | Problem frequencies, crossover shaping |\n\nIn modern practice, DSPs with parametric EQ sections have largely replaced hardware 1/3 octave equalizers for system tuning. However, 1/3 octave EQ curves remain a useful reference standard for specifying and verifying system frequency response, and are required by some acoustic commissioning standards.\n\n## Limitations\n\n- Minimum phase filters: boosts and cuts introduce phase shift, most audible when corrections exceed 6 dB[^6]\n- Fixed band spacing means a resonance that falls between two center frequencies requires simultaneous adjustment of two adjacent bands\n- Constant-Q designs produce asymmetrical curves at large boost/cut values\n\n---\n\n[^1]: White, Glenn; Louie, Gary (2005). [*The Audio Dictionary*](https://books.google.com/books?id=DulVm8t88QkC), 3rd ed. University of Washington Press. p. 140. ISBN 978-0-295-98498-8.\n[^2]: ISO 266:1997. [*Acoustics - Preferred frequencies*](https://www.iso.org/standard/3822.html). International Organization for Standardization.\n[^3]: Bohn, Dennis (August 1997). [\"Operator Adjustable Equalizers: An Overview\"](https://web.archive.org/web/20140402040654/http://www.rane.com/note122.html). Rane Corporation. Archived from the original 2014-04-02.\n[^4]: Hoffman, Frank, ed. (2005). [\"Davis, Arthur C. (11 Mar 1908 - 7 Nov 1970)\"](https://books.google.com/books?id=-FOSAgAAQBAJ&pg=PA550). *Encyclopedia of Recorded Sound*, 2nd ed. Routledge. p. 550. ISBN 978-1-135-94950-1.\n[^5]: Bohn, Dennis (August 1997). [\"Operator Adjustable Equalizers: An Overview\"](https://web.archive.org/web/20140402040654/http://www.rane.com/note122.html). Rane Corporation. (same source as [^3]; covers the Altec-Lansing Acousta-Voice system.)\n[^6]: Preis, Douglas; Bloom, P. J. (November 1984). [\"Perception of Phase Distortion in Anti-Alias Filters\"](https://aes2.org/publications/elibrary-page/?id=4476). *Journal of the Audio Engineering Society*, 32(11): 842-848."},{"title":"1/4-inch phone connector","url":"https://sane-av.github.io/glossary/14-inch-phone-connector/","type":"Glossary","snippet":"A connector typically used to transport unbalanced line-level audio signals from musical instruments and between processing devices. Also known as 6.35mm phone connector.","tags":["Audio","Cabling"],"text":"A connector typically used to transport unbalanced line-level audio signals from musical instruments and between processing devices. Also known as 6.35mm phone connector."},{"title":"1/8-inch phone connector","url":"https://sane-av.github.io/glossary/18-inch-phone-connector/","type":"Glossary","snippet":"A connector typically used to transport unbalanced line-level audio signals from portable devices and computers. Also known as 3.5mm phone connector.","tags":["Audio","Cabling"],"text":"A connector typically used to transport unbalanced line-level audio signals from portable devices and computers. Also known as 3.5mm phone connector."},{"title":"3.5mm phone connector","url":"https://sane-av.github.io/glossary/35mm-phone-connector/","type":"Glossary","snippet":"A connector typically used to transport unbalanced line-level audio signals from portable devices and computers. Also known as a 1/8-inch phone connector.","tags":["Audio","Cabling"],"text":"A connector typically used to transport unbalanced line-level audio signals from portable devices and computers. Also known as a 1/8-inch phone connector."},{"title":"4K","url":"https://sane-av.github.io/glossary/4k/","type":"Glossary","snippet":"An ultra-high-resolution video format with a minimum resolution of 3840×2160 pixels in a 16:9 (1.77:1) aspect ratio, approximately four times that of full HD (1920×1080 pixels). 4K formats include 3840×2160 pixels (UHDTV-1) and 4096×2160 pixels (digital cinema, DCI).","tags":["Video"],"text":"**4K** is a video resolution standard with a horizontal pixel count of approximately 4,000 pixels. Two distinct 4K specifications exist and are frequently confused:\n\n| Standard | Resolution | Aspect Ratio | Use |\n|---|---|---|---|\n| **DCI 4K** | 4096 × 2160 | 256:135 (≈1.90:1) | Digital cinema production and distribution |\n| **4K UHD** (UHDTV1) | 3840 × 2160 | 16:9 (1.78:1) | Consumer television, streaming, broadcast |\n\nBoth are approximately four times the pixel count of Full HD (1920 × 1080).\n\n## History\n\n### Cinema origins (2000-2005)\n\nJVC introduced the first 4K digital cinema projector in **2000** using D-ILA (Direct Drive Image Light Amplifier) technology.[^1] The first commercially available 4K camera for cinematographic use was the **Dalsa Origin**, released in **2003**.[^2] Sony began offering 4K digital cinema projectors in **2004**.[^3]\n\nIn **2005**, Digital Cinema Initiatives (DCI) - the consortium formed by the major Hollywood studios to standardize digital cinema - published the **Digital Cinema System Specification**, which established 4096 × 2160 as the 4K container format for cinema, with content resolutions defined by SMPTE 428-1.[^4] 4K digital projectors reached movie theaters in 2005 and had largely replaced analog film projectors by 2011.[^5]\n\n### Television standardization (2007-2012)\n\nIn **2007**, the Society of Motion Picture and Television Engineers published **SMPTE ST 2036-1**, defining the UHDTV1 system at 3840 × 2160 with square pixels and a 16:9 aspect ratio - the format now sold as \"4K UHD\" in consumer electronics.[^6]\n\nIn **2012**, the International Telecommunication Union published **ITU-R Recommendation BT.2020** (also called Rec. 2020), the UHDTV standard adopted internationally, which uses the same image parameters as SMPTE ST 2036-1.[^7]\n\nAlso in October **2012**, the Consumer Electronics Association (CEA, now CTA) defined **Ultra HD** for marketing purposes: a display requiring at least 3840 × 2160, 16:9 aspect ratio, at least one HDMI input supporting 4K at 24/30/60 Hz, and the ability to upscale HD content.[^8]\n\n### Consumer rollout (2013-present)\n\nConsumer 4K televisions dropped below US$700 by mid-2013 and below US$400 for smaller panels by 2015.[^9] YouTube began supporting 4K uploads in **2010** and added the explicit \"2160p\" quality option to its player in December 2013.[^10] Netflix began streaming 4K content in **2014** using HEVC (H.265) compression.[^11]\n\n**Ultra HD Blu-ray** - the physical disc format supporting 4K at up to 60 fps with HDR - launched in **March 2016**.[^12] The **2018 FIFA World Cup** was the first World Cup in which all matches were produced in 4K.[^13]\n\n## DCI 4K vs 4K UHD\n\nThe two specifications exist because cinema and television use different aspect ratios and have different production requirements:\n\n| | DCI 4K | 4K UHD |\n|---|---|---|\n| Resolution | 4096 × 2160 | 3840 × 2160 |\n| Aspect ratio | ≈1.90:1 | 16:9 (1.78:1) |\n| Frame rates | 24 fps (per DCI spec) | 23.976, 24, 25, 29.97, 30, 50, 59.94, 60, up to 120 Hz |\n| Color depth | 12-bit (cinema) | 10 or 12 bpc |\n| Governing standard | DCI DCSS / SMPTE 428-1 | SMPTE ST 2036-1 / ITU-R BT.2020 |\n| Primary use | Cinema theaters, professional production | Consumer TVs, streaming, broadcast |\n\nConsumer devices marketed as \"4K\" universally use the 3840 × 2160 UHD specification.\n\n## Relevant to AV Installations\n\n- **Cabling:** 4K UHD at 60 Hz with 4:4:4 color requires HDMI 2.0 (18 Gbps bandwidth) or DisplayPort 1.4. Earlier HDMI 1.4 supports 4K at 24/30 Hz only.\n- **Compression:** HEVC (H.265) is the standard codec for 4K streaming at 20-30 Mbit/s. AV over IP distribution typically uses 4:2:0 chroma subsampling at 4K, reducing color resolution to 1920 × 1080.\n- **Projection:** Native 4K projectors use DCI 4K chips (4096 × 2160). Many \"4K\" consumer projectors use pixel-shifting from a 1080p or 2716 × 1528 chip and do not resolve true 4K detail.\n- **4K ecosystem:** The end-to-end chain for 4K content includes capture (cameras), editing (NLEs and color grading systems), encoding, distribution infrastructure, and display. Each stage must be 4K-capable for the full resolution benefit to be realized at the viewer.\n\n---\n\n[^1]: Society for Information Display (SID). [\"50 Years of SID Symposia - Nurturing Progress in Projection Technology\"](https://www.sid.org/Portals/sid/Files/pdf/20121024%202.a.1.a%20Projection%20DTMC%20%20(Display%20Technology%20Milestone%20Chart)%20.pdf) (PDF). 2012-10-24.\n[^2]: Frost, Jacqueline B. (2009). [*Cinematography for Directors: A Guide for Creative Collaboration*](https://books.google.com/books?id=3aALmAEACAAJ). Michael Wiese Productions. p. 199. ISBN 978-1-932907-55-1.\n[^3]: [\"Sony Unveils New '4k' Digital Cinema Projector\"](http://www.projectorcentral.com/news_story_674.htm). Projector Central. June 3, 2004.\n[^4]: Digital Cinema Initiatives. [\"Digital Cinema System Specification v1.2\"](https://web.archive.org/web/20160527180135/http://dcimovies.com/specification/DCI_DCSS_v12_with_errata_2012-1010.pdf) (PDF). October 10, 2012. Archived 2016-05-27. §4.3.1, §3.2.1.\n[^5]: Truong, Alice. [\"4K is already playing at a theater near you\"](http://www.digitaltrends.com/photography/4k-is-already-playing-at-a-theater-near-you-but-you-probably-didnt-even-notice/). *Digital Trends*. August 6, 2013.\n[^6]: [SMPTE ST 2036-1:2014](https://doi.org/10.5594/smpte.st2036-1.2014). *Ultra High Definition Television - Image Parameter Values for Program Production*. Society of Motion Picture and Television Engineers.\n[^7]: ITU-R. [\"Ultra High Definition Television: Threshold of a new age\"](https://web.archive.org/web/20220328135502/https://www.itu.int/net/pressoffice/press_releases/2012/31.aspx). Press release, May 24, 2012. See also: [ITU-R Recommendation BT.2020-2](https://www.itu.int/dms_pubrec/itu-r/rec/bt/R-REC-BT.2020-2-201510-I!!PDF-E.pdf) (PDF). October 2015.\n[^8]: Consumer Electronics Association. [\"CEA Updates Characteristics for Ultra High-Definition Displays\"](https://www.cta.tech/News/Press-Releases/2014/June/CEA-Updates-Characteristics-for-Ultra-High-Definit.aspx). June 24, 2014.\n[^9]: Cox, Joe. [\"Seiki launches 39in 4K TV for $699\"](http://www.whathifi.com/news/seiko-launches-39in-4k-tv-for-699). *What Hi-Fi*. June 27, 2013.\n[^10]: Teoh, Vincent. [\"YouTube Adds '2160p 4K' Option To Video Quality Settings\"](http://www.hdtvtest.co.uk/news/youtube-2160p-201312253535.htm). HDTVTest. December 25, 2013.\n[^11]: Katzmaier, David. [\"Netflix begins 4K streams\"](https://www.cnet.com/au/news/netflix-begins-4k-streams/). CNET. April 8, 2014.\n[^12]: [\"The first ever Ultra HD 4K Blu-ray player has gone on sale\"](https://www.theverge.com/2016/2/8/10936792/uhd-4k-blu-ray-samsung-player-on-sale). *The Verge*. February 8, 2016.\n[^13]: [\"Fox, Telemundo Offer a Clearer View of FIFA World Cup Russia\"](https://www.tvtechnology.com/news/fox-telemundo-offer-a-clearer-view-of-fifa-world-cup-russia). *TV Technology*. Retrieved 2018-11-24."},{"title":"4K ecosystem","url":"https://sane-av.github.io/glossary/4k-ecosystem/","type":"Glossary","snippet":"The video cameras, recorders, editors, processors, servers, distribution networks, and display technologies used for the production, distribution, and display of 4K ultra-high-resolution video.","tags":["Video"],"text":"The video cameras, recorders, editors, processors, servers, distribution networks, and display technologies used for the production, distribution, and display of 4K ultra-high-resolution video."},{"title":"6.35mm phone connector","url":"https://sane-av.github.io/glossary/635mm-phone-connector/","type":"Glossary","snippet":"A connector typically used to transport unbalanced line-level audio signals from musical instruments and between processing devices. Also known as a 1/4-inch phone connector.","tags":["Audio","Cabling"],"text":"The **phone connector** is a family of cylindrical electrical connectors for analog audio signals. Invented in the late 19th century for telephone switchboards, it remains the dominant connector for electric instruments, headphone connections, and professional audio patch points more than 140 years later.\n\nThe connector is available in three standard diameters:\n\n| Size | Common Name | Typical Use |\n|---|---|---|\n| **6.35mm** | 1/4-inch | Professional audio, instruments, amplifiers |\n| **3.5mm** | 1/8-inch, mini | Consumer electronics, computers, headphones |\n| **2.5mm** | Sub-mini | Legacy mobile phones, two-way radios |\n\n## History\n\n### Switchboard origins (1877-1902)\n\nThe 1/4-inch phone connector traces its origin to **1877-1878**, when the first manual telephone exchanges were being built. The first telephone switchboard was installed in Boston in 1877.[^1] The first commercial manual telephone exchange opened in New Haven, Connecticut in 1878, created by George W. Coy.[^2]\n\nCharles E. Scribner filed the foundational switchboard patent in 1878 (U.S. Patent 293,198) introducing the spring-jack mechanism, and a follow-up in 1880 (U.S. Patent 489,570) that closely resembles the modern plug-and-socket form.[^3][^4] The socket was called a \"jack-knife\" - shortened to *jack* - because of its resemblance to a pocket clasp-knife. This is the origin of the word \"jack\" for the female connector.[^5]\n\nHenry P. Clausen filed a patent in 1901 (U.S. Patent 711,556) for the improved telephone switchboard plug whose 1/4-inch TS form is still used on audio equipment today.[^6] By 1907 Western Electric had codified multiple plug variants for different switchboard applications.[^7]\n\n### Adoption by broadcast and recording (1940s)\n\nBy the 1940s, U.S. broadcast radio stations were using Western Electric Code No. 103 plugs for studio patch panels - the same connector adopted from AT&T's Long Lines circuits. In the late 1940s the industry transitioned to 3-conductor TRS plugs (WE Type 291 with WE Type 239 jacks) to allow balanced routing without momentary shorts during insertion.[^8]\n\n### 3.5mm miniaturization (1950s-1979)\n\nThe 3.5mm connector was originally designed in the **1950s** as a two-conductor connector for earpieces on transistor radios.[^9] It was popularized by the Sony EFM-117J radio in **1964**.[^10] The three-conductor TRS variant became the global standard for portable audio after Sony introduced the **Walkman in 1979** - the first mass-market portable device with no built-in speaker, making headphones the primary listening method.[^9]\n\n### Decline in consumer devices (2012-present)\n\nThe 3.5mm jack began disappearing from smartphones starting with Oppo's Finder in July 2012, followed by LeEco in April 2016 and Apple's iPhone 7 in September 2016.[^11] The primary drivers were waterproofing requirements and device thinness. The connector remains universal in professional audio equipment, instruments, and desktop computers.[^12]\n\n## Conductor Configurations\n\n| Abbreviation | Conductors | Pin Assignment | Typical Use |\n|---|---|---|---|\n| **TS** (Tip, Sleeve) | 2 | Tip = signal, Sleeve = ground | Unbalanced instruments (guitar, bass) |\n| **TRS** (Tip, Ring, Sleeve) | 3 | Tip = hot, Ring = cold, Sleeve = ground | Balanced line level; stereo headphones |\n| **TRRS** (Tip, Ring, Ring, Sleeve) | 4 | Tip = L, Ring1 = R, Ring2 = ground/mic | Mobile headsets |\n| **TRRRS** | 5 | Two balanced channels | Balanced headphone output (4.4mm Pentaconn) |\n\n## Balanced vs. Unbalanced\n\nWhen wired as **TRS**, the connector carries a **balanced** signal - the hot and cold conductors carry phase-inverted copies of the audio. The receiving device subtracts the two signals, which cancels noise induced along the cable run (common-mode rejection). This makes balanced TRS suitable for professional cable runs.\n\nWhen wired as **TS**, the shield doubles as the signal return conductor, making it susceptible to hum and noise - acceptable for short instrument cable runs, problematic over longer distances.\n\nSee [SANE-001](/standards/SANE-001-audio-levels) for normative signal level specifications for each connector type.\n\n## Insertion Behavior and Switch Contacts\n\nPhone connectors make contact sequentially as the plug is inserted - the tip contacts before the ring and sleeve, momentarily shorting those conductors. Panel-mounted jacks frequently include **normally-closed (NC) switch contacts** that open when a plug is inserted. Common applications include:\n\n- **Patch bay normalling:** the NC contact bridges send-to-return when nothing is plugged in\n- **Headphone disconnection:** the NC contact disconnects loudspeaker outputs when headphones are plugged in\n- **Insert point bypass:** a TRS insert jack uses the NC contact to close the signal path when no outboard gear is connected [^13]\n\n## TRRS Wiring Standards\n\nTwo incompatible TRRS wiring orders exist for mobile headsets:\n\n| Standard | Tip | Ring 1 | Ring 2 | Sleeve | Common Devices |\n|---|---|---|---|---|---|\n| **CTIA / AHJ** | Left | Right | Ground | Mic | Apple iPhone (through 6S), most modern Android |\n| **OMTP** | Left | Right | Mic | Ground | Older Nokia, older Samsung, Chinese market devices |\n\nThe OMTP standard is defined in the OMTP Wired Analogue Audio specification and accepted as Chinese national standard YD/T 1885-2009.[^14] The CTIA/AHJ standard became the Western de facto standard following Apple's adoption in the iPhone.[^15] The 4-pole 3.5mm connector is defined by Japanese standard JEITA/EIAJ RC-5325A (originally published 1993).[^16]\n\n## Standards\n\n- **IEC 60603-11** / **EIA RS-453** - Dimensional and mechanical specifications for phone connectors\n- **JEITA/EIAJ RC-5325A** - 4-pole miniature concentric plugs and jacks (3.5mm TRRS)\n- **JIS C 6560** - 3-pole 3.5mm TRS connectors\n- **ITU-T P.382** - 5-conductor TRRRS standard for dual-microphone headsets\n\n## Notes on Compatibility\n\nPhysical compatibility between plug and socket of the same diameter does not guarantee electrical compatibility. Inserting a 2-conductor TS plug into a 3-conductor TRS jack shorts the ring to ground - potentially damaging amplifier outputs designed for an open ring. Inserting a 3-conductor TRS plug into a 2-conductor TS jack leaves the ring unconnected, losing one channel of a stereo signal or the cold leg of a balanced signal.[^17]\n\n---\n\n[^1]: Sherwin, Thomas. [\"The Birthplace of the Telephone\"](https://web.archive.org/web/20180819011644/http://www.newvision-sherwinpioneers.org/the-birthplace-of-the-telephone/). New Vision-Sherwin Pioneers. Archived from the original 2018-08-19.\n[^2]: [\"First Commercial Telephone Exchange - Today in History: January 28\"](https://connecticuthistory.org/the-first-commercial-telephone-exchange-today-in-history/). Connecticut History. 28 January 2020.\n[^3]: U.S. Patent 293,198 - Scribner, Charles E., \"Telephone-Switch\", issued 1884-02-05. [View at USPTO](https://patentimages.storage.googleapis.com/a6/07/a9/c8bf785c7d1260/US293198.pdf)\n[^4]: U.S. Patent 489,570 - Scribner, Charles E., \"Spring-Jack Switch\", issued 1893-01-10. [View at Google Patents](https://patents.google.com/patent/US489570A/en)\n[^5]: Chapuis, Robert J. (2003). *100 Years of Telephone Switching*. Amsterdam: IOS Press. p. 51. ISBN 978-4-274-90611-4.\n[^6]: U.S. Patent 711,556 - Clausen, Henry P., \"Telephone Switchboard-Plug\", issued 1902-10-21. [View at Google Patents](https://patents.google.com/patent/US711556/en)\n[^7]: [\"Western Electric Telephonic Apparatus and Supplies (1907)\"](http://www.telephonecollectors.info/index.php/browse/document-repository/catalogs-manuals/western-electric/we-catalogs/11201-1907ca-weco-telephonic-apparatus-and-supplies-catalog-ocr-r-large-file/file). Telephone Collectors International.\n[^8]: Chinn, Howard (July 1947). [\"Single Jacks for Broadcast Application\"](https://www.worldradiohistory.com/Archive-NAB-Engineering/NAB-4th-Edition/Section-5--NAB-Engineering-4th-Edition.pdf) (PDF). *Audio Engineering*. 31 (6).\n[^9]: [\"All-right jack: Simple but effective plug-in has endured for more than a century\"](http://www.cbc.ca/news/technology/apple-iphone-headphone-jack-history-1.3755120). CBC News. Retrieved 2016-09-11.\n[^10]: [\"Sony history 1960s\"](http://www.sony.net/Fun/design/history/1960.html). Sony.\n[^11]: [\"Apple is late, not early, to ditching the headphone jack\"](https://qz.com/776383/iphone-7-three-chinese-smartphone-makers-ditched-the-headphone-jack-before-apple). *Quartz*. 2016-09-08.\n[^12]: [\"Wired for Sound: A Musician's Guide to TS and TRS Cables\"](https://rockstockpedals.com/blogs/blog/wired-for-sound-a-musicians-guide-to-ts-and-trs-cables). RockStock Pedal Co. Archived 2024-04-17.\n[^13]: [\"The Low-down on Analogue Interfacing\"](https://www.soundonsound.com/sound-advice/low-down-analogue-interfacing). *Sound on Sound*. Retrieved 2018-08-16.\n[^14]: OMTP. [\"Wired Analogue Audio\"](http://www.omtp.org/OMTP_Local_Connectivity_Wired_Analogue_Audio_v1_0.pdf) (PDF). Retrieved 2012-06-01.\n[^15]: [\"Smartphone Headset Standards: Apple iPhone, AHJ (CTIA), & OMTP\"](http://help.longtailproducts.com/hc/en-us/articles/207970396). Headset Buddy Help.\n[^16]: [\"RC-5325A\"](https://www.jeita.or.jp/japanese/standard/book/RC-5325A/). JEITA.\n[^17]: [\"Understanding TRRS and Audio Jacks\"](https://www.cablechick.com.au/blog/understanding-trrs-and-audio-jacks/). Cable Chick. Archived 2023-11-06."},{"title":"8K","url":"https://sane-av.github.io/glossary/8k/","type":"Glossary","snippet":"An ultra-high-resolution video format with a minimum resolution of 7680×4320 pixels, which is 16 times the resolution of full HD (1920×1080 pixels). The related consumer television format is known as 7680p, 8K Ultra HD, and UHDTV-2.","tags":["Video"],"text":"**8K** is a video resolution standard with a horizontal pixel count of approximately 8,000 pixels. The primary standardized format is **8K UHD** (UHDTV2) at **7680 × 4320 pixels** in a 16:9 aspect ratio - exactly four times the pixel count of 4K UHD (3840 × 2160) and sixteen times that of Full HD (1920 × 1080).[^1]\n\n## Standards\n\n8K UHD is defined in two complementary standards:\n\n- **SMPTE ST 2036-1** (2007, revised 2014): Defines UHDTV2 at 7680 × 4320, with frame rates up to 120 Hz, 10 or 12 bits per channel, and colorimetry per ITU-R BT.2020.[^2]\n- **ITU-R Recommendation BT.2020** (2012): The international UHDTV standard that adopts the SMPTE parameters. ITU uses \"8K\" informally to refer to the 7680 × 4320 system.[^3]\n\nThe DVB project's UHD-2 standard also uses 7680 × 4320 for 8K broadcast distribution.[^4]\n\n## History\n\n### Early development\n\nNHK, Japan's national broadcaster, began researching what they called **Super Hi-Vision** (SHV) - their internal name for 8K - in the **1990s**. NHK conducted the first public demonstration of 8K at the IBC conference in 2003.[^5]\n\nIn **1984**, Hitachi's ARTC HD63484 graphics processor had already supported monochrome resolutions up to 4096 × 4096 interlaced for desktop publishing, but this was a single-chip display controller, not a video broadcast system.[^6]\n\n### Broadcast milestones\n\nNHK began experimental 8K test broadcasts in Japan in **2016** using BS satellite. The first regular scheduled 8K broadcast service, **NHK BS8K**, launched on **December 1, 2018** - making Japan the first country with a commercial 8K broadcast service.[^7]\n\nThe **2020 Tokyo Olympics** (held in 2021) were produced partly in 8K by NHK and served as the largest 8K production project to date.[^8]\n\n### Consumer market\n\nSamsung released the first mass-market 8K consumer television, the Q900R, in **2018**. Consumer 8K TV adoption has been extremely slow compared to 4K, due to the near-absence of native 8K content, extreme bandwidth requirements for distribution (streaming 8K requires approximately 50-100 Mbit/s), and the limited perceptibility of 8K vs 4K at typical living-room viewing distances for screen sizes under 85 inches.[^9]\n\n## AV Relevance\n\nAt typical professional AV installation viewing distances, 8K provides a perceptible resolution benefit only on very large displays (typically 85 inches and above) or at unusually close viewing distances. Most 8K content distributed today is upscaled from 4K sources.\n\n**Interface requirements:** 8K at 60 Hz with 4:2:0 color requires HDMI 2.1 (48 Gbps) or DisplayPort 2.0/2.1. No earlier interface standard supports 8K at full frame rates.\n\n**8K ecosystem:** The end-to-end chain for 8K content - including cameras, storage, editing infrastructure, encoding, distribution, and displays - is still maturing. Native 8K production is limited primarily to NHK, select high-budget cinema productions, and flagship consumer devices.\n\n---\n\n[^1]: [SMPTE ST 2036-1:2014](https://doi.org/10.5594/smpte.st2036-1.2014). *Ultra High Definition Television - Image Parameter Values for Program Production*. SMPTE. §5.2 (defines UHDTV2 at 7680 × 4320).\n[^2]: [SMPTE ST 2036-1:2014](https://doi.org/10.5594/smpte.st2036-1.2014). §1.2 (frame rates up to 120 Hz), §6.2 (sampling structure), §7.7 (colorimetry per ITU-R BT.2020).\n[^3]: ITU-R. [\"Ultra High Definition Television: Threshold of a new age\"](https://web.archive.org/web/20220328135502/https://www.itu.int/net/pressoffice/press_releases/2012/31.aspx). Press release, May 24, 2012.\n[^4]: DVB Project Office. [\"Phasing in Ultra High Definition\"](https://web.archive.org/web/20181222175820/https://www.dvb.org/resources/public/factsheets/dvb_-_phasing_in_uhd.pdf) (PDF). February 2017. Archived 2018-12-22.\n[^5]: NHK Science & Technology Research Laboratories. [\"Super Hi-Vision Research\"](https://www.nhk.or.jp/strl/english/publica/rd/rd147/pdf/P02-15.pdf) (PDF). NHK R&D, No. 147.\n[^6]: Peddie, Jon. [\"GPU History: Hitachi ARTC HD63484\"](https://www.computer.org/publications/tech-news/chasing-pixels/gpu-history-hitachi-artc-hd63484). *IEEE Computer Society*. 2018-10-07.\n[^7]: NHK. [\"NHK BS 8K Schedule\"](https://www.nhk.or.jp/bs8k/). NHK. (Service launched December 1, 2018.)\n[^8]: NHK Science & Technology Research Laboratories. [\"Super Hi-Vision (8K) Research\"](https://www.nhk.or.jp/strl/english/research/shv.html). NHK STRL. (NHK's 8K production program, including coverage of the Tokyo 2020 Olympic Games as the world's largest 8K production project.)\n[^9]: Cambridge University Research. [\"Is your ultra-HD TV worth it? Scientists measure the resolution limit of the human eye\"](https://www.cam.ac.uk/research/news/is-your-ultra-hd-tv-worth-it-scientists-measure-the-resolution-limit-of-the-human-eye). University of Cambridge. Retrieved 2026-04-29."},{"title":"8K ecosystem","url":"https://sane-av.github.io/glossary/8k-ecosystem/","type":"Glossary","snippet":"The video cameras, recorders, editors, processors, servers, distribution networks, and display technologies used for the production, distribution, and display of 8K ultra-high-resolution video.","tags":["Video"],"text":"The video cameras, recorders, editors, processors, servers, distribution networks, and display technologies used for the production, distribution, and display of 8K ultra-high-resolution video."},{"title":"8P8C connector","url":"https://sane-av.github.io/glossary/8p8c-connector/","type":"Glossary","snippet":"An eight-pin (eight position, eight conductor) modular connector typically used for the termination of multipair cables. Often used in Ethernet data networks. It is commonly incorrectly referred to as an RJ45 connector, which is actually an 8P2C telephone connector.","tags":["Networking","Electrical","Cabling"],"text":"The **8P8C connector** (8 Position, 8 Conductor) is a modular rectangular connector with eight positions, all of which are populated with conductors. It is the standard termination for twisted-pair Ethernet cabling and is almost universally - though incorrectly - called an **RJ45** connector.\n\n## The RJ45 Confusion\n\nRJ45 is a registered jack designation defined by the U.S. Federal Communications Commission (FCC) in 47 CFR Part 68. The actual RJ45 is an **8P2C** connector - 8 positions but only 2 conductors populated, wired for single-line telephone use with a keyed housing to prevent insertion into standard jacks.[^1] It is physically incompatible with the 8P8C connector used for Ethernet.\n\nThe misnomer became entrenched because the 8P8C connector superficially resembles an unkeyed 8-position modular connector, and early Ethernet documentation loosely used \"RJ45\" to describe it. Today, virtually every manufacturer, installer, and standards body outside the telecom regulatory context uses \"RJ45\" to mean the 8P8C Ethernet connector. This article uses the technically correct 8P8C designation, but both terms are in common use.[^2]\n\n## History\n\nThe modular connector family was developed by AT&T Bell Laboratories in the **1960s** to replace the bulky hardwired connections used in telephone installations. The modular jack and plug system was standardized by the FCC in the **Registration (RJ) program** starting in **1976**, which defined wiring configurations for connecting customer-provided telephone equipment to the public switched telephone network.[^3]\n\nThe 8-position modular plug was adopted for data networking as twisted-pair Ethernet (10BASE-T) was being developed in the late 1980s. IEEE 802.3i, published in **1990**, standardized 10BASE-T using twisted-pair cable terminated with 8P8C connectors.[^4] The same connector form factor has been carried forward through 100BASE-TX (Fast Ethernet), 1000BASE-T (Gigabit Ethernet), and 10GBASE-T.\n\n## Wiring Standards\n\nTwo pin-to-pair assignment standards exist for 8P8C Ethernet connectors, both defined in **TIA-568** (Telecommunications Infrastructure Standard for Commercial Buildings):\n\n| Pin | T568A | T568B |\n|---|---|---|\n| 1 | White/Green | White/Orange |\n| 2 | Green | Orange |\n| 3 | White/Orange | White/Green |\n| 4 | Blue | Blue |\n| 5 | White/Blue | White/Blue |\n| 6 | Orange | Green |\n| 7 | White/Brown | White/Brown |\n| 8 | Brown | Brown |\n\n**T568B** is the dominant standard in North America for commercial installations. **T568A** is specified by the U.S. federal government for government buildings and is required by some international standards.[^5]\n\nA cable must be wired consistently (same standard at both ends) for a **patch cable**. A **crossover cable** uses T568A at one end and T568B at the other, swapping the transmit and receive pairs - once required to connect two computers directly, now largely obsolete as modern switches and NICs support Auto-MDIX (automatic crossover detection).\n\n## Gigabit and 10G Ethernet\n\n- **10BASE-T / 100BASE-TX:** Use only 2 of the 4 pairs (pins 1-2 and 3-6).\n- **1000BASE-T (Gigabit Ethernet):** Uses all 4 pairs simultaneously for bidirectional transmission.\n- **10GBASE-T:** Also uses all 4 pairs; requires Cat6A or better cable to achieve 10 Gbps over 100 m.\n\n## Power over Ethernet (PoE)\n\nThe same 8P8C connector carries both data and DC power in PoE-enabled installations. IEEE 802.3af (PoE, up to 15.4 W), IEEE 802.3at (PoE+, up to 30 W), and IEEE 802.3bt (PoE++, up to 90 W) all use the 8P8C interface. See [power over Ethernet](/glossary/poe) for details.\n\n## Standards\n\n- **TIA-568.2-D** - Balanced twisted-pair telecommunications cabling and components standard (defines T568A/B wiring)\n- **ISO/IEC 11801** - International structured cabling standard (equivalent to TIA-568)\n- **IEEE 802.3** - Ethernet standard family covering 10BASE-T through 10GBASE-T\n- **IEC 60603-7** - Dimensional and performance specifications for 8-way modular connectors\n\n---\n\n[^1]: U.S. Federal Communications Commission. [47 CFR Part 68, Subpart F - Standard Plug and Jack Arrangements](https://www.ecfr.gov/current/title-47/chapter-I/subchapter-A/part-68/subpart-F). *Code of Federal Regulations*. (Defines RJ45 as an 8P2C keyed connector for single-line telephone use.)\n[^2]: Horowitz, Paul; Hill, Winfield (2015). [*The Art of Electronics*](https://www.worldcat.org/isbn/9780521809269), 3rd ed. Cambridge University Press. p. 898. ISBN 978-0-521-80926-9. (Notes the ubiquitous misnomer.)\n[^3]: FCC. [Registration Program for Telephone Equipment](https://transition.fcc.gov/cgb/consumerfacts/registrationprog.pdf) (PDF). *Consumer Facts*. (Background on the RJ registration program and Part 68.)\n[^4]: IEEE. [IEEE 802.3i-1990: Supplement to CSMA/CD Access Method and Physical Layer Specifications](https://ieeexplore.ieee.org/document/159164). IEEE Standards Association. 1990. (Standardized 10BASE-T over twisted-pair with 8P8C connectors.)\n[^5]: Telecommunications Industry Association. [*TIA-568.2-D: Balanced Twisted-Pair Telecommunications Cabling and Components Standard*](https://www.tiaonline.org/standards/tia-568-2-d/). 2018. (Defines T568A and T568B wiring schemes.)"},{"title":"acceptable viewing area","url":"https://sane-av.github.io/glossary/?search=acceptable%20viewing%20area","type":"Glossary","snippet":"The viewing range for a screen, suggested as a 60-degree arc off the far vertical edge of the screen being viewed.","tags":["Video"],"text":"The viewing range for a screen, suggested as a 60-degree arc off the far vertical edge of the screen being viewed."},{"title":"access point","url":"https://sane-av.github.io/glossary/?search=access%20point","type":"Glossary","snippet":"A network device that allows other devices to connect to a data network.","tags":["General"],"text":"A network device that allows other devices to connect to a data network."},{"title":"acoustic echo canceller","url":"https://sane-av.github.io/glossary/acoustic-echo-canceller/","type":"Glossary","snippet":"An echo cancelling device used in conferencing systems that attempts to remove environmental echoes that are created at the far site from sound reflected off hard surfaces and returned to conferencing microphones.","tags":["Acoustics","Audio"],"text":"An **acoustic echo canceller** (AEC) is a digital signal processing device or algorithm that removes the echo caused by a microphone picking up audio from a loudspeaker in the same room. It is a standard component in any conferencing system where the microphone and loudspeaker share the same space - including room conference systems, speakerphones, video bars, and unified communications endpoints.\n\nWithout AEC, the far-end talker hears their own voice returned to them after a delay equal to the round-trip network latency plus the acoustic path from loudspeaker to microphone. Delays longer than approximately 50 ms are perceived as a distinct, distracting echo.[^1]\n\n## How It Works\n\nAn AEC operates as an **adaptive filter**. The far-end received signal (the loudspeaker output) is used as a reference. The algorithm models the acoustic path from the loudspeaker to the microphone - including all reflections from room surfaces - and synthesizes an estimate of what the microphone will capture from that signal. This estimate is subtracted from the microphone signal, leaving only the near-end talker's voice.[^2]\n\nBecause the acoustic path changes continuously (people move, chairs shift, doors open), the filter must be adaptive: it constantly re-estimates the room impulse response. Modern systems converge from zero cancellation to 55 dB of echo suppression in approximately 200 ms.[^2]\n\nThe most common adaptive algorithm used is the **least mean squares** (LMS) filter and its variants. Performance is measured by:\n\n- **ERL** (Echo Return Loss): the ratio of loudspeaker output to the raw microphone echo, in dB. Higher = less raw echo.\n- **ERLE** (Echo Return Loss Enhancement): the additional suppression the canceller adds, typically 18-35 dB.\n- **ACOM** (total echo loss) = ERL + ERLE.[^1]\n\n### Double-talk\n\nThe hardest operating condition for AEC is **double-talk** - when both ends speak simultaneously. Naive LMS cancellers mis-adapt when double-talk is detected as a change in the acoustic path. Robust AEC implementations include a double-talk detector (DTD) that freezes filter adaptation when near-end speech is present.[^3]\n\n## History\n\nEcho suppression in telephone networks dates to the 1950s, when transoceanic satellite links first introduced delays long enough to be perceived. Early **echo suppressors** worked by muting the return path when voice was detected outgoing - simple but problematic during double-talk.[^4]\n\n**Echo cancellation** as a subtraction-based technique was developed at Bell Laboratories. M. M. Sondhi published the foundational paper on adaptive echo cancellation in 1967, and John Kelly received U.S. Patent 3,500,000 (filed 1966, issued 1970) for the \"Self-adaptive echo canceller\" at Bell Telephone Laboratories.[^5][^6] Commercial echo cancellers for telephone networks became available in the 1980s.[^7]\n\nThe development of affordable digital signal processors in the 1990s enabled AEC to move from standalone rack units to embedded modules within PBX switches and, eventually, to software running on general-purpose CPUs. Today, AEC is implemented in software on virtually every conferencing platform, smart speaker, and voice assistant device.\n\n## AEC in AV Systems\n\n| Application | Challenge |\n|---|---|\n| Conference room | Variable room acoustics, multiple microphones, distributed loudspeakers |\n| Ceiling microphone array | Long loudspeaker-to-mic paths; strong early reflections from table |\n| Video bar (all-in-one) | Loudspeaker and microphone are physically close; high coupling |\n| Wireless microphone base | No acoustic coupling; AEC often unnecessary |\n\nModern audio DSPs (e.g., from QSC, Biamp, Shure, ClearOne) implement multi-channel AEC covering the full speaker system rather than a single loudspeaker reference. This is critical in rooms with multiple ceiling speakers at different distances from the microphone.\n\n## Governing Standards\n\n- **ITU-T G.168** - Digital Network Echo Cancellers: performance requirements and tests\n- **ITU-T P.340** - Transmission characteristics and speech quality parameters for hands-free telephones\n- **TIA-920** - Transmission requirements for wideband digital wireline telephones (includes AEC requirements)\n\n---\n\n[^1]: Cisco Systems. [\"Echo Analysis for Voice over IP\"](http://www.cisco.com/c/en/us/td/docs/ios/solutions_docs/voip_solutions/EA_ISD.html). Cisco IOS Solutions Documentation. Retrieved 2014-07-02. (Defines ERL, ERLE, ACOM; discusses 50 ms perception threshold.)\n[^2]: Eneroth, Peter (2001). [*Stereophonic Acoustic Echo Cancellation: Theory and Implementation*](http://lup.lub.lu.se/luur/download?func=downloadFile&recordOId=41259&fileOId=1001945) (PDF). Doctoral thesis, Lund University. ISBN 91-7874-110-6. (Covers adaptive filter theory, convergence times, double-talk.)\n[^3]: Åhgren, Per (November 2005). [\"Acoustic Echo Cancellation and Doubletalk Detection Using Estimated Loudspeaker Impulse Responses\"](https://www.cs.columbia.edu/~hgs/research/projects/echo-detection/Acoustic%20Echo%20Cancellation%20and%20Doubletalk%20Detection.pdf) (PDF). *IEEE Transactions on Speech and Audio Processing*. 13 (6): 1231-1237. doi:10.1109/TSA.2005.851995.\n[^4]: Murano, Kazuo; Unagami, Shigeyuki; Amano, Fumio (January 1990). [\"Echo Cancellation and Applications\"](https://web.archive.org/web/20140415211711/http://www.ece.rochester.edu/courses/ECE472/resources/Papers/Murano_1990.pdf) (PDF). *IEEE Communications Magazine*. 28 (1): 49-55. doi:10.1109/35.46671. (Surveys history from 1950s suppressors through 1980s commercial cancellers.)\n[^5]: Sondhi, Man Mohan (March 1967). [\"An adaptive echo canceler\"](https://web.archive.org/web/20140416031355/http://www3.alcatel-lucent.com/bstj/vol46-1967/articles/bstj46-3-497.pdf) (PDF). *Bell System Technical Journal*. 46 (3): 497-511. doi:10.1002/j.1538-7305.1967.tb04231.x. (Foundational paper on adaptive echo cancellation.)\n[^6]: U.S. Patent 3,500,000 - Kelly Jr., John L., \"Self-adaptive echo canceller\", issued 1970-03-10, assigned to Bell Telephone Laboratories, Inc. [View at Google Patents](https://patents.google.com/patent/US3500000).\n[^7]: Kosanovic, Bogdan (2002-04-11). [\"Echo Cancellation Part 1: The Basics and Acoustic Echo Cancellation\"](http://www.eetimes.com/document.asp?doc_id=1277615). *EE Times*. Retrieved 2014-07-07."},{"title":"acoustics","url":"https://sane-av.github.io/glossary/acoustics/","type":"Glossary","snippet":"The properties or qualities of a room or building that determine how sound is transmitted and reflected. The study of the properties of sound.","tags":["Acoustics"],"text":"**Acoustics** is the branch of physics that deals with the generation, propagation, and effects of mechanical waves in gases, liquids, and solids - commonly called sound. In AV and architectural contexts, the term is used more narrowly to mean the acoustic properties of a room or space: the sum of all characteristics that determine how sound behaves within it.\n\nANSI/ASA S1.1-2013 gives the dual definition: \"(a) Science of sound, including its production, transmission, and effects, including biological and psychological effects. (b) Those qualities of a room that, together, determine its character with respect to auditory effects.\"[^1]\n\n## History\n\nThe study of acoustics is among the oldest sciences. In the 6th century BCE, Pythagoras observed that the pleasing intervals in music corresponded to simple integer ratios of string lengths - the first quantitative study of vibrating strings.[^2] Aristotle (~350 BCE) described sound as compressions and rarefactions of air that propagate outward - a remarkably accurate description of longitudinal wave propagation.[^3]\n\nAround 20 BCE, the Roman architect Vitruvius wrote *De architectura* (Book V), the earliest known treatise on architectural acoustics. He described sound as a wave analogous to water ripples, analyzed echo and reflection in theaters, and recommended that the rising seats of Greek theaters were designed to prevent the deterioration of sound as it traveled upward.[^4]\n\nDuring the Scientific Revolution, Galileo Galilei (1564-1642) and Marin Mersenne (1588-1648) independently completed the mathematical description of vibrating strings. Mersenne's *Harmonie universelle* (1634) laid out the relationship between string length, tension, mass, and pitch.[^5] The speed of sound in air was measured successfully between 1630 and 1680 by multiple investigators.\n\nIn 1687, Isaac Newton derived the relationship for wave propagation velocity in solids in *Philosophiae Naturalis Principia Mathematica* - a cornerstone of physical acoustics.[^5]\n\nThe 19th century produced the two great systematizers of acoustics: Hermann von Helmholtz, whose *On the Sensations of Tone* (1863) founded physiological and psychoacoustics; and Lord Rayleigh, whose *The Theory of Sound* (1877-1878) remains a foundational reference, combining all prior knowledge with Rayleigh's own extensive contributions.[^6]\n\n### Architectural acoustics and Wallace Clement Sabine\n\nThe applied discipline of **architectural acoustics** - designing rooms for predictable acoustic behavior - was founded by Wallace Clement Sabine (1868-1919) at Harvard University. In 1900, Sabine published his measurement of **reverberation time** (now called RT60): the time for sound to decay by 60 dB after the source stops. He derived the empirical formula:\n\n$$RT_{60} = \\frac{0.161 \\cdot V}{A}$$\n\nwhere $V$ is room volume in cubic meters and $A$ is the total acoustic absorption in sabins.[^7] This formula, and the unit named in his honor, remain in daily use by acoustic consultants worldwide.\n\n## Key Concepts for AV Professionals\n\n### Reverberation\n\nSound continues to reflect off room surfaces after the source stops. The length of this decay (RT60) determines whether a space favors music (longer RT - 1.5-2.5 s for orchestral halls) or speech intelligibility (shorter RT - 0.4-0.8 s for conference rooms). See also: [SANE-001](/standards/SANE-001-audio-levels) for signal level requirements that interact with reverberation.\n\n### Absorption, reflection, and diffusion\n\nEvery material in a room has a **absorption coefficient** (0 = perfect reflector, 1 = perfect absorber) that varies by frequency. Acoustic treatment combines:\n\n| Treatment type | Function |\n|---|---|\n| Absorbers (foam, fiberglass, fabric panels) | Reduce reflections, lower RT60 |\n| Diffusers (QRD, skyline panels) | Scatter reflections evenly, prevent standing waves |\n| Bass traps (thick absorbers in corners) | Control low-frequency room modes |\n| Reflectors (hard, angled surfaces) | Direct early reflections beneficially (e.g., toward audience) |\n\n### Room modes (standing waves)\n\nIn enclosed spaces, sound at frequencies whose half-wavelengths divide evenly into the room dimensions creates **standing waves** (resonant modes). These cause severe frequency-response irregularities at low frequencies - some seats receive extreme bass emphasis, others a bass null. Modal frequencies are approximately:\n\n$$f = \\frac{c}{2} \\sqrt{\\left(\\frac{n_x}{L_x}\\right)^2 + \\left(\\frac{n_y}{L_y}\\right)^2 + \\left(\\frac{n_z}{L_z}\\right)^2}$$\n\nwhere $c$ = speed of sound, $L_x, L_y, L_z$ = room dimensions, $n_x, n_y, n_z$ = integers.[^8]\n\n### Noise criterion\n\nBackground noise in a space limits the usable signal-to-noise ratio of speech. [HVAC, mechanical, and electrical noise](/glossary/noise-criterion) is rated using NC (Noise Criterion) or NCB curves. Recommended NC ratings for AV spaces: conference rooms 25-35, boardrooms 25-30, home theaters 20-25.\n\n## Subdisciplines Relevant to AV\n\n- **Architectural acoustics** - design of performance venues, classrooms, conference rooms, studios\n- **Electroacoustics** - loudspeakers, microphones, and the electronic manipulation of acoustic signals\n- **Psychoacoustics** - how humans perceive sound (loudness, localization, masking, intelligibility)\n- **Room acoustics** - modeling and measuring how sound behaves within enclosed spaces\n\n## Key Standards\n\n- **ANSI/ASA S1.1** - Acoustical Terminology\n- **ISO 3382-1** - Acoustics: Measurement of room acoustic parameters (performance spaces)\n- **ISO 3382-2** - Acoustics: Measurement of room acoustic parameters (ordinary rooms)\n- **ASTM E336** - Standard test method for airborne sound attenuation between rooms\n- **ANSI/ASHRAE 189.1** - includes acoustic requirements for sustainable buildings\n\n---\n\n[^1]: [ANSI/ASA S1.1-2013](https://acousticalsociety.org/standards/). *Acoustical Terminology*. Acoustical Society of America. (Definition 12.04, \"acoustics\"; Definition 12.06, \"room acoustics\".)\n[^2]: Boyer, C.; Merzbach, U. (1991). [*A History of Mathematics*](https://www.worldcat.org/isbn/9780471543978). Wiley. p. 55. ISBN 978-0-471-54397-8.\n[^3]: Princeton University Press. [\"How Sound Propagates\"](http://press.princeton.edu/chapters/s9912.pdf) (PDF). Quoting Aristotle's *Treatise on Sound and Hearing*. Archived from the original 2022-10-09.\n[^4]: Vitruvius Pollio. [*The Ten Books on Architecture*](https://archive.org/details/vitruviustenbook00vitr_0), Book V, §6-8. Tr. Morris Hickey Morgan, 1914. Harvard University Press.\n[^5]: Pierce, Allan D. (1989). [*Acoustics: An Introduction to its Physical Principles and Applications*](https://www.worldcat.org/isbn/0883186128). Acoustical Society of America. ISBN 0-88318-612-8.\n[^6]: Rayleigh, Lord (John Strutt, 3rd Baron Rayleigh) (1877). [*The Theory of Sound*](https://archive.org/details/theoryofsound01raylgoog), Volume 1. Macmillan and Co. (Reprinted Dover, 1945. ISBN 978-0-486-60292-9.)\n[^7]: Sabine, Wallace Clement (1900). \"Reverberation.\" *The American Architect*. Reprinted in: Sabine, W.C. (1922). [*Reverberation and Other Factors*](https://archive.org/details/reverberation00sabi). Harvard University Press. (Original derivation of the Sabine reverberation formula.)\n[^8]: Kinsler, L.E. et al. (1999). [*Fundamentals of Acoustics*](https://www.worldcat.org/isbn/9780471847892), 4th ed. Wiley. ISBN 978-0-471-84789-2."},{"title":"AC (alternating current)","url":"https://sane-av.github.io/glossary/?search=alternating%20current","type":"Glossary","snippet":"An electric current that reverses its direction periodically.","tags":["Electrical"],"text":"An electric current that reverses its direction periodically."},{"title":"ambient light","url":"https://sane-av.github.io/glossary/?search=ambient%20light","type":"Glossary","snippet":"The sum of all lighting in an area.","tags":["Lighting"],"text":"The sum of all lighting in an area."},{"title":"ambient noise","url":"https://sane-av.github.io/glossary/?search=ambient%20noise","type":"Glossary","snippet":"The sum of all sounds in an area.","tags":["General"],"text":"The sum of all sounds in an area."},{"title":"amperage","url":"https://sane-av.github.io/glossary/?search=amperage","type":"Glossary","snippet":"The amount of electric current flowing in a circuit. Current is measured in amperes (amps), abbreviated as A. The preferred term is “current.”","tags":["Electrical"],"text":"The amount of electric current flowing in a circuit. Current is measured in amperes (amps), abbreviated as A. The preferred term is “current.”"},{"title":"amplifier","url":"https://sane-av.github.io/glossary/amplifier/","type":"Glossary","snippet":"A device for increasing the strength of signals.","tags":["Audio"],"text":"An **amplifier** is a device that increases the power, voltage, or current of a signal. In AV systems, the term most commonly refers to a **power amplifier** - a device that takes a line-level audio signal and produces sufficient electrical power to drive one or more loudspeakers. The fundamental principle is that a small input signal controls a larger output signal drawn from a power supply, with the ratio of output to input being the **gain**.\n\n## Classes of Amplifier Operation\n\nPower amplifiers are classified by how their output transistors (or tubes) are biased relative to the signal cycle. The class determines the tradeoff between efficiency and distortion:\n\n| Class | Conduction angle | Efficiency | Distortion | Common AV Use |\n|---|---|---|---|---|\n| **A** | 360° (always on) | ≤25% | Very low | High-end audio |\n| **B** | 180° (half cycle each) | ~78% | Crossover distortion | Obsolete in audio |\n| **AB** | >180° (slight overlap) | 50-70% | Low | Most professional and consumer audio |\n| **D** | Switching (PWM) | 85-95% | Low with good filtering | Install amps, powered speakers |\n| **G/H** | AB with supply rail switching | 70-80% | Low | Touring amplifiers |\n\n**Class D** (switching) amplifiers dominate modern professional AV installations because of their high efficiency, low heat generation, and compact form factor. The \"D\" designation does not stand for \"digital\" - a Class D amplifier modulates a carrier signal (typically 300 kHz-1 MHz) using pulse-width modulation and is compatible with analog signal paths.[^1]\n\n## History\n\n### Vacuum tubes (1906-1950s)\n\nThe triode vacuum tube, invented by Lee de Forest in **1906** (U.S. Patent 841,387), was the first practical amplifying device.[^2] It enabled the amplification of audio signals for public address, radio broadcast, and telephony - applications that previously required acoustic horns or were impossible over distance. The first public address system using vacuum tube amplifiers was demonstrated by AT&T engineers in 1916 at a political event in Baltimore, Maryland.[^3]\n\nThrough the 1920s-1940s, vacuum tube amplifiers powered virtually all public address systems, radio transmitters, and early cinema sound systems. The Western Electric 555W receiver (1926) and the associated amplifier systems established the first standardized cinema audio chain.[^4]\n\n### Transistors and solid state (1947-present)\n\nThe bipolar junction transistor was invented by Bardeen, Brattain, and Shockley at Bell Laboratories in **December 1947**.[^5] Transistorized amplifiers began displacing tube designs in professional audio during the 1960s, offering greater reliability, lower operating voltage, and smaller size. By the 1970s, solid-state designs dominated professional AV.\n\n### Integrated circuits and Class D (1960s-present)\n\nThe operational amplifier (op-amp) as an integrated circuit - first realized as the Fairchild µA709 (1965) and refined as the µA741 (1968) - enabled compact, stable gain stages that became ubiquitous in audio processing equipment.[^6]\n\nClass D switching amplifier technology was patented as early as 1958 (Baxandall, UK Patent 848,029), but practical audio-grade Class D amplifiers required fast switching transistors and precision PWM control that only became economically viable in the 1990s-2000s.[^7]\n\n## Types in AV Systems\n\n| Type | Description |\n|---|---|\n| **Power amplifier** | Line-level input → speaker-level output; provides wattage to drive loudspeakers |\n| **Preamplifier** | Low-level source signals → line level; provides gain and source selection |\n| **Distribution amplifier** | Splits and amplifies a signal to multiple outputs without level loss |\n| **Headphone amplifier** | Low-power amplifier matched to headphone impedance (typically 8-600 Ω) |\n| **Microphone preamplifier** | Amplifies mic-level signals (~-60 to -40 dBu) to line level; may include phantom power |\n| **Installed sound amplifier** | Multi-channel power amp optimized for fixed installation; often rackmounted |\n| **70V / 100V amplifier** | Drives a constant-voltage distribution system for distributed speaker networks |\n\n## Key Specifications\n\n- **Power output** (watts RMS into rated load impedance, typically 8 Ω or 4 Ω)\n- **Total Harmonic Distortion + Noise (THD+N)** at rated power (lower = cleaner)\n- **Signal-to-noise ratio** (dB below rated output)\n- **Frequency response** (±dB over 20 Hz-20 kHz)\n- **Damping factor** (output impedance relative to nominal load; higher = tighter bass control)\n- **Input sensitivity** (what input voltage produces rated output)\n- **Bridgeable** (whether two channels can be combined for higher mono power)\n\n## Gain Structure Interaction\n\nSee also: [gain structure](/glossary/gain-structure). An amplifier's input sensitivity must be matched to the output level of the preceding device (DSP, mixer, preamplifier) so that full output power is reached when the upstream device is at its nominal operating level. Mismatched gain structure - operating the amplifier's gain control at maximum while the upstream signal is low - degrades signal-to-noise ratio.\n\n---\n\n[^1]: Self, Douglas (2013). [*Audio Power Amplifier Design*](https://www.worldcat.org/isbn/9780240526133), 6th ed. Focal Press / Routledge. ISBN 978-0-240-52613-3. (Chapter 17: Class D amplifiers; clarifies the \"D does not mean digital\" point.)\n[^2]: U.S. Patent 841,387 - de Forest, Lee, \"Device for amplifying feeble electrical currents\", issued 1907-01-15. [View at Google Patents](https://patents.google.com/patent/US841387).\n[^3]: Engineering and Technology History Wiki. [\"Milestones: Public Address System, 1915\"](https://ethw.org/Milestones:Public_Address_System,_1915). IEEE History Center. (IEEE Milestone designation for the first practical public address system developed by AT&T engineers; first public demonstration 1916.)\n[^4]: Altman, Rick (1995). [*Sound Theory, Sound Practice*](https://www.worldcat.org/isbn/9780415908801). Routledge. ISBN 978-0-415-90880-1. (Chapter on Western Electric cinema sound standardization, pp. 44-46.)\n[^5]: Riordan, Michael; Hoddeson, Lillian (1997). [*Crystal Fire: The Birth of the Information Age*](https://www.worldcat.org/isbn/9780393041248). Norton. ISBN 978-0-393-04124-8. (Account of the transistor's invention at Bell Labs, December 1947.)\n[^6]: Williams, Jim (1990). [*Analog Circuit Design*](https://www.worldcat.org/isbn/9780750691663). Butterworth-Heinemann. ISBN 978-0-7506-9166-3. (History of the op-amp from µA709 to µA741, pp. 1-6.)\n[^7]: Baxandall, Peter J. [UK Patent GB848029A - \"Transistor sine wave LC oscillators\"](https://worldwide.espacenet.com/patent/search?q=PN%3DGB848029). Application 1958, published 1960. (Early Class D/switching amplifier concept. Cited in Self 2013 Chapter 17 as first Class D patent.)"},{"title":"amplitude","url":"https://sane-av.github.io/glossary/?search=amplitude","type":"Glossary","snippet":"The height of the waveform of a signal.","tags":["General"],"text":"The height of the waveform of a signal."},{"title":"analog","url":"https://sane-av.github.io/glossary/?search=analog","type":"Glossary","snippet":"A continuously variable signal.","tags":["General"],"text":"A continuously variable signal."},{"title":"analog-to-digital/digital-to-analog (AD/DA or A to D/D to A) converters","url":"https://sane-av.github.io/glossary/?search=analog-to-digital%2Fdigital-to-analog%20(AD%2FDA%20or%20A%20to%20D%2FD%20to%20A)%20converters","type":"Glossary","snippet":"Devices that convert signals from analog to digital or from digital to analog.","tags":["Signal Processing"],"text":"Devices that convert signals from analog to digital or from digital to analog."},{"title":"angularly reflective screen","url":"https://sane-av.github.io/glossary/?search=angularly%20reflective%20screen","type":"Glossary","snippet":"A screen that reflects light at the same angle at which it arrived.","tags":["Video"],"text":"A screen that reflects light at the same angle at which it arrived."},{"title":"anthropometrics","url":"https://sane-av.github.io/glossary/?search=anthropometrics","type":"Glossary","snippet":"Results of the study of the measurements and proportions of the human body.","tags":["Systems & Control"],"text":"Results of the study of the measurements and proportions of the human body."},{"title":"aperture","url":"https://sane-av.github.io/glossary/?search=aperture","type":"Glossary","snippet":"The opening in an optical train that controls the amount of light passing through.","tags":["Video","Cabling"],"text":"The opening in an optical train that controls the amount of light passing through."},{"title":"AFCI (arc-fault circuit interrupter)","url":"https://sane-av.github.io/glossary/?search=arc-fault%20circuit%20interrupter","type":"Glossary","snippet":"Also known as an arc-fault detection device (AFDD), a type of circuit breaker that triggers on detecting an electrical-arc fault in its load circuit.","tags":["Video","Electrical"],"text":"Also known as an arc-fault detection device (AFDD), a type of circuit breaker that triggers on detecting an electrical-arc fault in its load circuit."},{"title":"arrayed loudspeaker system","url":"https://sane-av.github.io/glossary/?search=arrayed%20loudspeaker%20system","type":"Glossary","snippet":"A loudspeaker arrangement that delivers sound from a single point in space.","tags":["Audio"],"text":"A loudspeaker arrangement that delivers sound from a single point in space."},{"title":"artifact","url":"https://sane-av.github.io/glossary/?search=artifact","type":"Glossary","snippet":"An element introduced into a signal during processing.","tags":["Signal Processing"],"text":"An element introduced into a signal during processing."},{"title":"aspect ratio","url":"https://sane-av.github.io/glossary/aspect-ratio/","type":"Glossary","snippet":"The ratio of image width to image height.","tags":["Video"],"text":"**Aspect ratio** is the ratio of an image's width to its height, expressed as width:height or as a decimal (width ÷ height). It defines the shape of the image frame and is independent of resolution - the same aspect ratio can be rendered at many different pixel counts.\n\n## Common Aspect Ratios in AV\n\n| Ratio | Decimal | Name | Use |\n|---|---|---|---|\n| **4:3** | 1.33:1 | \"Academy ratio\" / SDTV | Standard definition television; legacy computer monitors |\n| **16:9** | 1.78:1 | \"Widescreen\" / HDTV | All current broadcast, streaming, consumer TV, conferencing |\n| **1.85:1** | 1.85:1 | \"Flat\" cinema | Most Hollywood theatrical releases since ~1953 |\n| **2.39:1** | 2.39:1 | \"Scope\" / anamorphic | Widescreen theatrical cinema (anamorphic lens format) |\n| **1:1** | 1.00:1 | Square | Instagram, some social media video |\n| **9:16** | 0.56:1 | Vertical | Mobile-first video (TikTok, Stories) |\n| **21:9** | 2.37:1 | Ultrawide | Ultrawide desktop monitors; some cinematic streaming content |\n| **17:9** | 1.89:1 | DCI container | Digital cinema distribution container (encompasses 1.85:1 and 2.39:1) |\n\n## History\n\n### Early cinema and the Academy ratio\n\nThe earliest projected films (1890s) used 35 mm film with a frame roughly 4:3. The **Academy ratio** of 1.37:1 (sometimes loosely called \"4:3\") was standardized by the Academy of Motion Picture Arts and Sciences in **1932** as the standard sound film aperture, after the optical soundtrack on 35 mm film reduced the usable image width from the silent-era 1.33:1.[^1]\n\n### The widescreen transition (1953-1960)\n\nThe introduction of **CinemaScope** (1953) - an anamorphic lens system licensed from Henri Chrétien's Hypergonar design - marked the television industry's first direct challenge to cinema's dominance. CinemaScope squeezed a wide image onto standard 35 mm film using an anamorphic lens and expanded it on projection to 2.55:1, later standardized at **2.39:1** (or \"2.40:1\" per SMPTE 195).[^2]\n\n**1.85:1 flat widescreen** emerged in the US in 1953 as studios began using a wider crop of the Academy aperture (top and bottom masked off in projection). It became the standard theatrical ratio for non-anamorphic Hollywood productions.\n\n### Television standardization\n\nStandard definition television globally used **4:3** (the NTSC, PAL, and SECAM systems all share this aspect ratio). The move to 16:9 for high-definition television was standardized by:\n\n- **ITU-R Recommendation BT.709** (1990, revised 2015): the primary HDTV standard, specifying 16:9.[^3]\n- **SMPTE ST 274** (1995): standardized 1080-line production formats at 16:9.\n- **FCC Report and Order** (1996): mandated the US transition to ATSC HDTV, which uses 16:9.\n\nConsumer televisions transitioned from 4:3 to 16:9 during the 2000s. By 2010, 16:9 had become the universal consumer and professional video standard.\n\n## Aspect Ratio Mismatch\n\nWhen content and display have different aspect ratios, one of three approaches is used:\n\n| Method | What happens | Tradeoff |\n|---|---|---|\n| **Letterboxing** | Black bars top and bottom | Full image visible; reduces effective screen use |\n| **Pillarboxing** | Black bars left and right | Full image visible; reduces effective screen use |\n| **Cropping** | Image edges cut off | Full screen used; content lost |\n| **Stretching** | Image distorted to fill | Full screen used; incorrect geometry |\n\n**\"Windowboxing\"** (or \"double-letterbox\") occurs when a 4:3 signal is letterboxed into 16:9 space, then that 16:9 is pillarboxed onto a different 16:9 display - producing four black bars.\n\n## AV Installation Considerations\n\n- **Projection screens:** Screen manufacturers list width × height and aspect ratio. A 16:9 screen at 120\" diagonal has a different width and height than a 2.35:1 screen at the same diagonal. Always specify both diagonal and aspect ratio.\n- **Multi-screen installations:** When multiple displays are tiled or adjacent, consistent aspect ratios simplify content mapping.\n- **Videoconferencing:** All major video conferencing platforms (Teams, Zoom, Webex) use 16:9 video frames. Camera sensors, display surfaces, and content should all be 16:9.\n- **Anamorphic projection:** Some premium home theater and screening rooms use a 2.35:1 or 2.39:1 screen with a 16:9 projector and an anamorphic lens (or electronic zoom/lens memory). This preserves native projector resolution for scope content at the cost of hardware complexity. See [throw ratio](/glossary/throw-ratio) for projection geometry calculations.\n\n---\n\n[^1]: Lipton, Lenny (1982). [*The Super 8 Book*](https://www.worldcat.org/isbn/0671253263). Simon & Schuster. ISBN 0-671-25326-5. (Covers Academy aperture history and the 1932 standardization.) Also: SMPTE Journal Vol. 89 (1980), documenting Academy aperture specifications.\n[^2]: Carr, Robert E. and Hayes, R. M. (1988). [*Wide Screen Movies: A History and Filmography of Wide Gauge Filmmaking*](https://www.worldcat.org/isbn/9780899502427). McFarland. ISBN 978-0-89950-242-9. (Documents CinemaScope development, Chrétien's Hypergonar, and 2.55:1 → 2.39:1 standardization.)\n[^3]: ITU-R. [Recommendation BT.709-6: Parameter values for the HDTV standards for production and international programme exchange](https://www.itu.int/dms_pubrec/itu-r/rec/bt/R-REC-BT.709-6-201506-I!!PDF-E.pdf) (PDF). June 2015. (Table 1 specifies 16:9 aspect ratio for all HDTV systems.)"},{"title":"attack time","url":"https://sane-av.github.io/glossary/?search=attack%20time","type":"Glossary","snippet":"The time taken for an action to complete its effect once triggered.","tags":["Audio"],"text":"The time taken for an action to complete its effect once triggered."},{"title":"attenuate","url":"https://sane-av.github.io/glossary/?search=attenuate","type":"Glossary","snippet":"To reduce the amplitude of a signal.","tags":["Signal Processing"],"text":"To reduce the amplitude of a signal."},{"title":"Audio Coverage Uniformity measurement locations","url":"https://sane-av.github.io/glossary/?search=Audio%20Coverage%20Uniformity%20measurement%20locations","type":"Glossary","snippet":"The test points within a venue that have been determined to carry out the measurements for the Audio Coverage Uniformity test.","tags":["Audio","Standards"],"text":"The test points within a venue that have been determined to carry out the measurements for the Audio Coverage Uniformity test."},{"title":"ACUP (Audio Coverage Uniformity Plan)","url":"https://sane-av.github.io/glossary/?search=Audio%20Coverage%20Uniformity%20Plan","type":"Glossary","snippet":"A stand-alone document that identifies the Audio Coverage Uniformity measurement locations for a particular venue, using the indication symbol.","tags":["Audio","Standards"],"text":"A stand-alone document that identifies the Audio Coverage Uniformity measurement locations for a particular venue, using the indication symbol."},{"title":"audio processor","url":"https://sane-av.github.io/glossary/?search=audio%20processor","type":"Glossary","snippet":"A device used to manipulate audio signals.","tags":["Audio"],"text":"A device used to manipulate audio signals."},{"title":"ARC (Audio Return Channel)","url":"https://sane-av.github.io/glossary/audio-return-channel-arc/","type":"Glossary","snippet":"Introduced to the HDMI standard with version 1.4. ARC allows a display to send audio data upstream to a receiver or surround-sound controller, eliminating the need for a separate audio connection.","tags":["Audio","Video"],"text":"**Audio Return Channel (ARC)** is a feature of HDMI that allows a television to send audio upstream to an AV receiver or soundbar over the same HDMI cable used to carry video downstream. It eliminates the need for a separate optical (TOSLINK) or coaxial digital audio cable to return sound from the TV's built-in tuner, streaming apps, or other TV-internal sources.\n\n**Enhanced ARC (eARC)**, introduced in HDMI 2.1, replaces ARC with a higher-bandwidth version that supports lossless and object-based audio formats.\n\n## HDMI ARC vs eARC\n\n| Feature | ARC (HDMI 1.4+) | eARC (HDMI 2.1) |\n|---|---|---|\n| Introduced | HDMI 1.4 (2009) | HDMI 2.1 (2017) |\n| Max audio bandwidth | ~1 Mbit/s (S/PDIF parity) | ~37 Mbit/s |\n| Stereo PCM | Yes | Yes |\n| Dolby Digital (AC-3) | Yes | Yes |\n| DTS | Yes | Yes |\n| Dolby Digital Plus | Yes (2-ch fallback) | Yes (full quality) |\n| Dolby TrueHD / Atmos (lossless) | No | Yes |\n| DTS-HD Master Audio / DTS:X | No | Yes |\n| Multi-channel LPCM | No (2-ch only) | Up to 192 kHz, 24-bit |\n| Lip sync correction | Manual | Automatic (per spec) |\n| Cable requirement | Standard HDMI (any) | High-Speed HDMI (48 Gbps rated preferred) |\n\nARC's bandwidth limitation (equivalent to S/PDIF at ~3 Mbit/s net) prevents it from carrying lossless audio or the full object-based metadata for Dolby Atmos and DTS:X. eARC resolves this with a dedicated high-speed Ethernet channel repurposed for audio, enabling uncompressed multi-channel PCM and full lossless bitstreams.[^1]\n\n## History\n\nARC was introduced as part of the **HDMI 1.4 specification** published in **May 2009**.[^2] Prior to ARC, a common TV installation required:\n1. HDMI cable from AV receiver to TV (video forward path)\n2. Optical TOSLINK cable from TV audio out to AV receiver (audio return path)\n\nARC eliminated the optical cable. However, in practice, ARC proved unreliable due to implementation differences between manufacturers, particularly around HDMI CEC (Consumer Electronics Control) handshaking - the control protocol ARC depends on to negotiate the audio return path. Incompatibility between ARC implementations across different TV and receiver brands became a frequent consumer complaint.\n\n**HDMI eARC** (part of the **HDMI 2.1 specification**, published **November 2017**) was developed to address both the bandwidth limitation and the reliability problems of ARC.[^3] eARC uses a dedicated pin pair (HDMI pins 13 and 14, formerly used for HEC - HDMI Ethernet Channel) for a separate high-speed audio channel independent of CEC. This makes eARC more robust and adds an identification protocol (EDID-like) that allows devices to negotiate capabilities without depending on CEC.\n\n## Practical AV Installation Notes\n\n- **Port specificity:** ARC and eARC only function on a specifically designated HDMI port on the TV (typically labeled \"ARC\" or \"eARC\"). Similarly, on the AV receiver or soundbar, only the ARC-capable input supports the return channel.\n- **CEC dependency (ARC):** ARC requires HDMI CEC to be enabled on both the TV and the receiving device. Many consumers and integrators disable CEC to avoid unintended device control, which also disables ARC.\n- **eARC independence:** eARC does not depend on CEC for audio transport (though CEC is still used for some control functions). This makes eARC more reliable in installations where CEC is disabled.\n- **Lossless passthrough:** If the goal is Dolby Atmos or DTS:X lossless audio from a TV's streaming app (e.g., Apple TV app on a Samsung TV), eARC is required. ARC will deliver a lossy Dolby Digital Plus bitstream at best.\n- **Backward compatibility:** eARC ports are backward compatible with ARC. An ARC device connected to an eARC port will use ARC mode.\n\n## Related: HDMI CEC\n\nARC and eARC work alongside **HDMI CEC**, which allows control signals (volume, power, input selection) to pass over the HDMI cable. TV manufacturers brand CEC under proprietary names: Samsung calls it Anynet+, Sony calls it Bravia Sync, LG calls it SimpLink. All are compliant with the HDMI CEC protocol but interoperability between different brands remains inconsistent.\n\n---\n\n[^1]: HDMI Forum. [*HDMI Specification 2.1*](https://www.hdmi.org/spec21Sub/EArc). Section on eARC. 2017. (Defines eARC bandwidth at 37 Mbit/s, dedicated audio channel, and lossless format support.)\n[^2]: HDMI Licensing LLC. [*High-Definition Multimedia Interface Specification Version 1.4*](https://www.hdmi.org/spec/14). May 28, 2009. (Introduced ARC, 3D video, and HDMI Ethernet Channel.)\n[^3]: HDMI Forum. [*High-Definition Multimedia Interface Specification Version 2.1*](https://www.hdmi.org/spec/21). November 2017. (Section 7.7: Enhanced Audio Return Channel; specifies the HEC pin repurposing and eARC discovery protocol.)"},{"title":"audio signal","url":"https://sane-av.github.io/glossary/?search=audio%20signal","type":"Glossary","snippet":"An electrical representation of sound.","tags":["Audio"],"text":"An electrical representation of sound."},{"title":"audio transduction","url":"https://sane-av.github.io/glossary/?search=audio%20transduction","type":"Glossary","snippet":"The process of converting acoustical energy into electrical energy or electrical energy back into acoustical energy.","tags":["Acoustics","Audio"],"text":"The process of converting acoustical energy into electrical energy or electrical energy back into acoustical energy."},{"title":"AVB (Audio Video Bridging)","url":"https://sane-av.github.io/glossary/audio-video-bridging-avb/","type":"Glossary","snippet":"A standards-based audiovisual Data Link-layer (layer 2) protocol defined under IEEE 802.1-AVB. It runs across a standard Ethernet network but requires AVB-enabled switches and network components that handle QoS prioritization of data. AVB has been renamed Time-Sensitive Networking to reflect the standard’s applicability to communication among different types of devices, such as network sensors.","tags":["Audio","Video","Networking","Standards"],"text":"**Audio Video Bridging (AVB)** is a set of IEEE 802.1 standards that extends standard Ethernet to provide deterministic, low-latency transport for time-sensitive audio and video streams. It guarantees bounded latency (typically 2 ms end-to-end) and precise clock synchronization across an Ethernet network - capabilities that standard \"best effort\" Ethernet cannot provide.\n\nThe AVB standard family later evolved into the broader **Time-Sensitive Networking (TSN)** framework, which extends the same deterministic capabilities to industrial automation, automotive, and other domains.\n\n## Core Standards\n\nAVB is a suite of interrelated IEEE standards, not a single document:\n\n| Standard | Full name | Function |\n|---|---|---|\n| **IEEE 802.1AS** | Timing and Synchronization (gPTP) | Distributes a common network clock with sub-microsecond accuracy |\n| **IEEE 802.1Qav** | Credit-Based Shaper (CBS) | Reserves bandwidth and smooths traffic to prevent burst-induced latency |\n| **IEEE 802.1Qat** | Stream Reservation Protocol (SRP) | Enables endpoints to reserve bandwidth for a stream end-to-end through the network |\n| **IEEE 802.1BA** | AVB Systems | Defines system-level requirements combining the above three |\n\nAll four standards were published by 2011. IEEE 802.1Qav and 802.1Qat were later folded into IEEE 802.1Q (the main Ethernet bridging standard) as clauses 34 and 35 respectively.[^1]\n\n### IEEE 802.1AS - Generalized Precision Time Protocol (gPTP)\n\nAVB requires all devices to share a common clock. 802.1AS implements a profile of IEEE 1588 (Precision Time Protocol, PTP) designed for Ethernet networks. A **grandmaster clock** distributes timing to all AVB switches and endpoints. Devices synchronize to within approximately 1 microsecond of each other, enabling sample-accurate audio playout across the network.[^2]\n\n### IEEE 802.1Qav - Credit-Based Shaper\n\nStandard Ethernet switches transmit packets on a \"best effort\" basis. A large video frame can block a switch port, delaying a small audio packet. The Credit-Based Shaper (CBS) allocates bandwidth \"credits\" to time-sensitive traffic classes. An AVB stream spends credits to transmit, then waits to accumulate them - ensuring no single stream monopolizes bandwidth and bounding worst-case latency.\n\n### IEEE 802.1Qat - Stream Reservation Protocol\n\nBefore an AVB stream is established, the source endpoint uses SRP to signal bandwidth requirements through every switch along the path. Each switch either admits the reservation (if sufficient bandwidth is available) or rejects it. This prevents the network from becoming overcommitted - a stream is either reliably admitted or explicitly rejected.[^3]\n\n## History\n\nThe AVB working group within IEEE 802.1 was formed in **2005**. The first published AVB standard was 802.1AS in **2011**, followed closely by 802.1Qav and 802.1Qat.\n\nEarly industry adoption was led by **Apple**, which included AVB hardware support in Mac Pro, Mac mini, and Thunderbolt interfaces starting in **2011-2012**, positioning AVB for professional audio workstations and studios. However, AVB adoption in the broader professional AV market was slower than anticipated, partly due to the requirement for AVB-capable network switches (standard unmanaged switches do not support AVB).\n\nIn **2015**, the **Milan** protocol was launched by the AVnu Alliance (the AVB industry certification body) and major audio networking vendors (AVID, Yamaha, L-Acoustics, others) to address interoperability gaps in the base AVB standard. Milan is a strict profile of AVB that mandates specific discovery, registration, and media clock requirements to ensure plug-and-play interoperability between different vendors' AVB devices.[^4]\n\n## AVB vs Competing Protocols\n\n| Protocol | Transport | Sync | Latency | Network requirement | Interop standard |\n|---|---|---|---|---|---|\n| **AVB / Milan** | IEEE 802.1 (Layer 2) | IEEE 802.1AS (gPTP) | ≤2 ms (1 hop) | AVB-capable switches | IEEE 802.1BA / Milan spec |\n| **Dante** | IP/UDP (Layer 3) | PTPv2 (IEEE 1588) | ~1 ms (typical) | Managed or unmanaged Ethernet | AES67 compatible |\n| **RAVENNA** | IP/RTP (Layer 3) | PTPv2 | ~1 ms | Standard IP network | AES67 native |\n| **AES67** | IP/RTP | PTPv2 | 1 ms (min) | Standard IP network | Industry standard |\n| **Dante via AES67** | IP/UDP bridged | PTPv2 | ~1 ms | Standard Ethernet | AES67 gateway |\n\nA key difference between AVB and IP-based protocols (Dante, RAVENNA, AES67): AVB streams are routed at Layer 2 (MAC address / VLAN), while IP protocols route at Layer 3. AVB cannot traverse standard IP routers; IP protocols can be routed across WAN links.\n\n## AV Industry Usage\n\nAVB in its Milan profile is used by:\n- **L-Acoustics** (P1 processor, LA Network Manager)\n- **d&b audiotechnik** (DS100 Signal Engine)\n- **Yamaha** (mixing consoles with EtherSound/AVB ports)\n- **Meyer Sound** (Galileo GALAXY processors)\n\nThe AVnu Alliance operates a compliance testing program. Only certified devices carry the AVnu mark and are verified for interoperability.\n\n---\n\n[^1]: IEEE 802.1 Working Group. [IEEE Std 802.1Q-2018](https://ieeexplore.ieee.org/document/8403927): *Bridges and Bridged Networks*. IEEE Standards Association. 2018. doi:10.1109/IEEESTD.2018.8403927. (Clause 34: Credit-Based Shaper; Clause 35: Stream Reservation Protocol.)\n[^2]: IEEE Standards Association. [IEEE Std 802.1AS-2020](https://ieeexplore.ieee.org/document/9121845): *Timing and Synchronization for Time-Sensitive Applications*. IEEE. 2020. doi:10.1109/IEEESTD.2020.9121845.\n[^3]: IEEE Standards Association. [IEEE Std 802.1Qat-2010](https://ieeexplore.ieee.org/document/5594708): *Stream Reservation Protocol*. IEEE. 2010. doi:10.1109/IEEESTD.2010.5594708.\n[^4]: AVnu Alliance. [Milan Specification v1.2](https://avnu.org/milan/). AVnu Alliance. 2021. (Defines Milan as a strict profile of IEEE 802.1BA with mandatory discovery via AVDECC and fixed media clock requirements for interoperability.)"},{"title":"audiovisual infrastructure","url":"https://sane-av.github.io/glossary/?search=audiovisual%20infrastructure","type":"Glossary","snippet":"The physical building components that make up the pathways, supports, and architectural elements required for audiovisual technical equipment installations.","tags":["General"],"text":"The physical building components that make up the pathways, supports, and architectural elements required for audiovisual technical equipment installations."},{"title":"audiovisual rack","url":"https://sane-av.github.io/glossary/?search=audiovisual%20rack","type":"Glossary","snippet":"A housing unit for electronic equipment. The inside of a typical AV industry rack is 19in. (482.6mm) wide. Many of the technical specifications for a rack, including size and equipment height, are determined by standards that have been established by numerous standards-setting organizations. The outside width of the rack varies from approximately 530mm to 630mm (21in. to 25in.).","tags":["Project Management"],"text":"A housing unit for electronic equipment. The inside of a typical AV industry rack is 19in. (482.6mm) wide. Many of the technical specifications for a rack, including size and equipment height, are determined by standards that have been established by numerous standards-setting organizations. The outside width of the rack varies from approximately 530mm to 630mm (21in. to 25in.)."},{"title":"authentication","url":"https://sane-av.github.io/glossary/?search=authentication","type":"Glossary","snippet":"The ability or process of verifying the identity of an entity, such as a user, process, or device, for providing access to resources such as AV systems.","tags":["Security"],"text":"The ability or process of verifying the identity of an entity, such as a user, process, or device, for providing access to resources such as AV systems."},{"title":"AHJ (authority having jurisdiction)","url":"https://sane-av.github.io/glossary/?search=authority%20having%20jurisdiction","type":"Glossary","snippet":"An organization, office, or individual responsible for enforcing the requirements of a code or standard or for approving equipment, materials, installation, or procedures. In some places the authority having jurisdiction may be known as the regional regulatory authority.","tags":["Project Management"],"text":"An organization, office, or individual responsible for enforcing the requirements of a code or standard or for approving equipment, materials, installation, or procedures. In some places the authority having jurisdiction may be known as the regional regulatory authority."},{"title":"authorization","url":"https://sane-av.github.io/glossary/?search=authorization","type":"Glossary","snippet":"The process used to determine whether a user is granted access to a specific resource by evaluating relevant access control information.","tags":["Security"],"text":"The process used to determine whether a user is granted access to a specific resource by evaluating relevant access control information."},{"title":"AGC (automatic gain control)","url":"https://sane-av.github.io/glossary/automatic-gain-control-agc/","type":"Glossary","snippet":"A circuit or process that maintains a constant output gain in response to input variables such as signal strength or ambient noise level.","tags":["Audio","Electrical"],"text":"**Automatic gain control (AGC)** is a feedback circuit or algorithm that continuously adjusts the gain applied to a signal in order to maintain a relatively constant output level despite varying input levels. When the input is loud, AGC reduces gain; when the input is quiet, AGC increases it.\n\nAGC differs from a compressor in intent: a compressor is used deliberately to shape dynamics for artistic or technical purposes, while AGC is a \"set and forget\" mechanism designed to make a variable signal appear approximately constant. In practice the distinction is technical rather than functional - an AGC is essentially an automatic compressor with a long time constant.\n\n## How It Works\n\nAn AGC circuit measures the signal level (typically using a peak or RMS detector) and compares it against a target setpoint. A control voltage (or digital value) is generated to drive a voltage-controlled amplifier (VCA) or digital gain stage:\n\n- **Attack time**: how quickly the gain is reduced when level rises above the setpoint\n- **Release time** (or decay time): how slowly the gain recovers when level falls below the setpoint\n- **Threshold**: the level at which gain control begins\n\nLong release times are common in AGC designs to avoid the audible \"breathing\" (level swelling up in pauses) that occurs when release is too fast.\n\n## History\n\nAGC was first developed for radio receivers. **Harold Wheeler** at RCA described and patented **automatic volume control (AVC)** - the original term for AGC in broadcast receivers - in a 1925 paper and subsequent patents.[^1] AVC was incorporated into AM radio receivers by the late 1920s and became a standard feature. It solved a fundamental problem: AM broadcast signals varied enormously in strength depending on atmospheric conditions and distance, causing uncomfortable volume swings as listeners moved across the dial.\n\nThe same principle was adapted to recording and transmission systems throughout the 1930s-1950s. The BBC and other broadcast organizations used automatic gain riding on transmission links to maintain consistent levels over long-distance circuits.[^2]\n\nWith the introduction of solid-state VCAs in the 1970s and early DSPs in the 1980s, AGC moved from discrete analog circuits into integrated audio processing. Modern DSP-based AGC algorithms are used in virtually every conferencing system, hearing aid, and mobile phone microphone.\n\n## Applications in AV Systems\n\n| Application | Why AGC is used | Risk |\n|---|---|---|\n| Wireless microphone receivers | Compensates for RF path variation and presenter distance | Raises noise floor during silence; can amplify HVAC noise |\n| Video conferencing endpoints | Normalizes volume across multiple talkers at different distances | May amplify someone whispering across the room |\n| Public address in variable environments | Adjusts for varying crowd noise and source distance | Pumping artifacts when ambient noise changes abruptly |\n| Hearing loops and assistive listening | Maintains consistent level for hearing impaired users | Level changes may confuse hearing aid wearers |\n| Recording to a fixed-bit-depth recorder | Prevents clipping when source level is unknown | Destroys dynamic contrast in music performance |\n\n## AGC vs Manual Gain vs Compression\n\n| Approach | Control | Use case |\n|---|---|---|\n| Manual gain (fixed) | Human operator sets gain once | Predictable source levels; professional productions |\n| AGC | Automatic, slow-acting feedback | Unattended systems, public address, telephony |\n| Compressor (fast attack) | Automatic, fast-acting | Broadcast loudness control, live music |\n| Limiter | Automatic, instantaneous | Clipping prevention; last line of defense |\n\nIn professional AV installations, AGC is generally avoided on program audio because it removes dynamic information. It is acceptable for speech-only systems where consistent intelligibility matters more than preserving dynamics. See also: [gain structure](/glossary/gain-structure).\n\n---\n\n[^1]: Wheeler, Harold A. (1928). \"Automatic Volume Control for Radio Receiving Sets.\" *Proceedings of the Institute of Radio Engineers*, 16(10): 30-31. U.S. Patent 1,743,523 - Wheeler, Harold A., [\"Automatic volume control\"](https://patents.google.com/patent/US1743523), filed 1925, issued 1930-01-14. (Original AVC/AGC patent and foundational paper.)\n[^2]: Engineering and Technology History Wiki. [\"Harold A. Wheeler\"](https://ethw.org/Harold_A._Wheeler). IEEE History Center. (Biography documenting Wheeler's invention of AVC and its widespread adoption in commercial broadcast receivers from the late 1920s.)"},{"title":"balanced circuit","url":"https://sane-av.github.io/glossary/balanced-circuit/","type":"Glossary","snippet":"A two-conductor circuit in which both conductors and all circuits connected to them have the same impedance with respect to ground.","tags":["Electrical","Signal Processing"],"text":"A **balanced circuit** is an electrical circuit consisting of two conductors that have equal impedances along their lengths, to ground, and to all other circuits. In professional audio, a balanced circuit carries a signal on two conductors simultaneously - one the \"hot\" (positive polarity) conductor and the other the \"cold\" (negative polarity) conductor - while the impedances of both conductors to ground remain equal.\n\nThe primary advantage of a balanced circuit is its rejection of **common-mode interference**: noise induced by external electromagnetic fields affects both conductors equally and in phase. Because the receiving device responds only to the *difference* between the two conductors, the equal (common-mode) noise is subtracted out and the signal is recovered cleanly.[^1]\n\n## How Common-Mode Rejection Works\n\nWhen an external noise source (power line hum, RF interference, lighting dimmers) couples into a cable, it induces the same voltage on both conductors - this is common-mode noise. At the receiving end, a transformer or differential amplifier subtracts one conductor from the other. The signal, which is equal-and-opposite on the two conductors, doubles in amplitude; the noise, which is equal and in-phase, cancels to zero.\n\nThe effectiveness of this cancellation is measured as **Common-Mode Rejection Ratio (CMRR)**, expressed in dB. A well-designed balanced input has CMRR of 60 dB or higher at 60 Hz (power line frequency), meaning hum is attenuated by 1000:1 or more relative to signal.[^2]\n\n**Critical distinction:** Impedance balance - not signal symmetry - is what provides noise rejection. A balanced circuit does not require equal-and-opposite signals on both conductors; it requires equal impedances from both conductors to ground. A circuit with asymmetric impedances will have differential noise pickup even if the signals are symmetric.[^1]\n\n## History\n\nThe balanced line principle was first applied to telephone networks in the late 19th century. Early telephone lines run alongside electric power lines suffered severe interference. Engineers at Bell Telephone resolved this by routing telephone wire as pairs, and later by introducing **crossover transpositions** - swapping the two conductors every few hundred yards to equalize the total interference induced on each leg. This technique, which is the physical precursor to the electrical balance concept, was in use by the 1890s.[^3]\n\nThe systematic mathematical understanding of balanced circuits as impedance-matched differential systems was formalized during the development of long-distance telephony in the early 20th century. By the 1930s, balanced circuits were standard practice for professional audio over telephone trunk lines, and the principles were codified in Bell System Technical References.[^3]\n\nThe **XLR connector** - the standard physical interface for balanced audio - was developed by Cannon Electric in the 1950s (originally the Cannon X series, later modified to XLR) and became the universal professional audio connector for balanced microphone and line-level signals.[^4]\n\n## Balanced vs Unbalanced\n\n| Property | Balanced | Unbalanced |\n|---|---|---|\n| Conductors | 2 signal + 1 ground shield | 1 signal + 1 ground (return) |\n| Connector (audio) | XLR (3-pin), TRS | TS, RCA, 3.5mm TS |\n| Noise rejection | High (CMRR 60+ dB) | None beyond shield |\n| Max practical cable run | 100+ m (analog audio) | ~6 m before noticeable noise |\n| Typical use | Microphones, professional line level | Consumer audio, guitar, headphones |\n\n## Pin Assignment (AES14 / EIA RS-297-A)\n\nFor XLR connectors, the standard pin assignment per AES14-1992 is:\n- **Pin 1**: Ground (shield)\n- **Pin 2**: Hot (positive, \"+\" polarity)\n- **Pin 3**: Cold (negative, \"-\" polarity)\n\nThis \"Pin 2 Hot\" convention is universal in professional AV. Older British and some European equipment used \"Pin 3 Hot\"; connecting the two results in a 180° phase reversal (polarity inversion) rather than signal loss.\n\n## Star Quad Cable\n\nStandard balanced audio cable uses a twisted pair. **Star quad** cable uses four conductors arranged in a square, with diagonally opposite conductors connected together to form the two legs. This geometry provides additional rejection of magnetic field interference (not just electric field) by ensuring that any external magnetic field induces equal flux in both pairs. Star quad is preferred for long microphone runs in high-interference environments.[^2]\n\n---\n\n[^1]: Ballou, Glen, ed. (2015). [*Handbook for Sound Engineers*](https://www.worldcat.org/isbn/041584293X), 5th ed. Taylor & Francis. pp. 1267-1268. ISBN 041584293X. (\"Only the common-mode impedance balance of the driver, line, and receiver play a role in noise or interference rejection. This noise or interference rejection property is independent of the presence of a desired differential signal.\")\n[^2]: Benchmark Media. [\"The Importance of Star-Quad Microphone Cable\"](https://benchmarkmedia.com/blogs/application_notes/116637511-the-importance-of-star-quad-microphone-cable). Benchmark Media Systems. (Technical note on CMRR measurement and star quad geometry.)\n[^3]: Huurdeman, Anton A. (2003). [*The Worldwide History of Telecommunications*](https://www.wiley.com/en-us/The+Worldwide+History+of+Telecommunications-p-9780471205050). Wiley-IEEE Press. pp. 314-323. ISBN 978-0-471-20505-0. (History of balanced telephone lines, crossover transpositions, and twisted-pair cabling from the 1890s through 1912.)\n[^4]: Whitlock, Bill (2014). [\"Audio System Grounding and Interfacing: An Overview\"](https://www.jensentransformers.com/an/an004.pdf) (PDF). Jensen Transformers Application Note AN-004. (History of the XLR connector, pin 2 hot convention, and balanced circuit theory for AV practitioners.)"},{"title":"balun","url":"https://sane-av.github.io/glossary/balun/","type":"Glossary","snippet":"A contraction of balanced-to-unbalanced. A device used to connect a balanced circuit to an unbalanced circuit. For example, a transformer used to connect a 300-ohm television antenna cable (balanced) to a 75-ohm antenna cable (unbalanced).","tags":["Electrical","Cabling","Signal Processing"],"text":"A **balun** (contraction of *balanced-to-unbalanced*) is a passive electrical device used to interface a balanced circuit with an unbalanced circuit. Baluns provide impedance transformation and/or signal conversion between the two circuit types while maintaining isolation between them.\n\nIn AV systems, baluns appear in two main contexts:\n1. **Audio baluns** - coupling balanced professional audio (XLR) to unbalanced consumer equipment (RCA, 3.5mm), or routing audio over UTP (unshielded twisted pair) structured cabling\n2. **Video baluns** - transmitting composite, component, or SDI video over balanced twisted-pair cable instead of coaxial cable\n\n## How Baluns Work\n\nA transformer-based balun uses electromagnetic coupling between two windings. The unbalanced side connects to one winding (center-tap grounded); the balanced side connects to the other winding with its center-tap grounded or floating. The transformer provides both the balanced-to-unbalanced conversion and galvanic isolation (no DC path between sides), which blocks ground loops.\n\nAn active balun (sometimes called a \"line driver\" or \"line receiver\") uses differential amplifier circuits rather than a transformer. Active baluns can provide gain and often have wider frequency response, but do not provide galvanic isolation.\n\n## Impedance Transformation\n\nBaluns also serve as impedance transformers. A 4:1 balun transforms between a 300 Ω balanced line (classic TV antenna twin-lead) and a 75 Ω unbalanced coaxial input. The impedance transformation ratio equals the square of the winding turns ratio:\n\n$$Z_{ratio} = \\left(\\frac{N_1}{N_2}\\right)^2$$\n\n## History\n\nThe balun concept in telecommunications dates to the development of the telephone network in the late 19th century, where **repeating coils** (audio transformers with center-tapped windings) were used to couple balanced telephone lines to two-wire and four-wire circuits.[^1] The term \"balun\" itself emerged in RF engineering in the mid-20th century with the development of antenna systems that required coupling balanced dipole antennas to unbalanced coaxial feedlines.[^2]\n\nIn professional audio, transformer-based baluns became essential as studios mixed professional balanced equipment (operating at +4 dBu) with consumer unbalanced equipment (operating at -10 dBV). Jensen Transformers, founded in 1974, became the leading manufacturer of audio baluns for this purpose, and their application notes remain reference documents for balanced/unbalanced interfacing.[^3]\n\nThe use of baluns to extend audio and video over structured cabling (UTP) became widespread in the 1990s-2000s as commercial AV installations sought to reuse existing network cable runs. This technique - sometimes called \"CCTV over UTP\" or \"AV over Cat5\" - uses passive or active balun pairs at each end of a Cat5/6 run to convert between the unbalanced signal at the AV device and the balanced signal on the twisted pair.\n\n## Types by Application\n\n| Type | Use | Notes |\n|---|---|---|\n| Audio balun (passive) | XLR ↔ RCA; professional ↔ consumer level | Transformer-based; provides galvanic isolation |\n| UTP audio balun | Audio over structured cabling (Cat5e/6) | Replaces long balanced XLR runs with network cable |\n| Video balun (passive) | Composite or component video over twisted pair | Supports runs up to ~300 m for composite |\n| SDI balun | SDI video over twisted pair (active, regenerative) | Active; restores signal quality |\n| RF balun | Dipole antenna ↔ coaxial feedline | Common 300Ω twin-lead to 75Ω coax |\n| HDBaseT extender | HDMI over Cat5e/6 (active) | Not a simple balun; a full protocol converter |\n\n## Common AV Installation Uses\n\n- **Hum elimination:** A transformer balun between a laptop headphone output and a mixing console breaks the ground loop that causes 60 Hz hum when both devices share a power circuit.\n- **Long cable runs:** A passive audio balun pair can extend line-level audio 100+ meters over Cat5 cable, far beyond the practical limit of unbalanced coaxial runs.\n- **Rack equipment grounding:** Balanced transformer isolation between sources and amplifiers prevents ground noise from noisy dimmer circuits from entering the audio chain.\n\n---\n\n[^1]: Huurdeman, Anton A. (2003). [*The Worldwide History of Telecommunications*](https://www.wiley.com/en-us/The+Worldwide+History+of+Telecommunications-p-9780471205050). Wiley-IEEE Press. pp. 320-325. ISBN 978-0-471-20505-0. (History of repeating coils and transformer coupling in telephone networks.)\n[^2]: Sevick, Jerry (2001). [*Transmission Line Transformers*](https://www.worldcat.org/isbn/9781884932182), 4th ed. Noble Publishing. ISBN 978-1-884932-18-2. (Definitive reference on RF balun design; covers history of the term and development for antenna applications.)\n[^3]: Whitlock, Bill (2014). [\"Audio System Grounding and Interfacing: An Overview\"](https://www.jensentransformers.com/an/an004.pdf) (PDF). Jensen Transformers Application Note AN-004. (Practical guide to audio balun selection, grounding, and hum elimination in professional AV systems.)"},{"title":"band","url":"https://sane-av.github.io/glossary/?search=band","type":"Glossary","snippet":"A grouping or range of frequencies.","tags":["General"],"text":"A grouping or range of frequencies."},{"title":"bandwidth","url":"https://sane-av.github.io/glossary/bandwidth/","type":"Glossary","snippet":"1. A range of frequencies. 2. A measure of the amount of data or signal that can pass through a system during a given time interval.","tags":["General"],"text":"**Bandwidth** has two distinct meanings in AV systems, both in common use:\n\n1. **Analog/acoustic bandwidth** - the range of frequencies a signal, device, or channel can carry; measured in Hz\n2. **Network/digital bandwidth** - the maximum data rate of a digital communication link or channel; measured in bits per second (bit/s) or multiples thereof (Mbit/s, Gbit/s)\n\nThe two usages are related - higher analog bandwidth in a digital system requires more network bandwidth to represent it - but the terms refer to different physical quantities and should not be used interchangeably.\n\n---\n\n## Analog Bandwidth\n\nIn analog audio and video, bandwidth refers to the span of frequencies a device or signal path can handle. It is typically defined as the range of frequencies over which a device's response remains within a specified tolerance (commonly ±3 dB).\n\n### Audio Bandwidth\n\nHuman hearing spans approximately **20 Hz to 20,000 Hz** (20 kHz). Professional audio equipment is typically specified to be flat (±0.5 dB or better) across this range. The usable audio bandwidth of various systems:\n\n| System | Bandwidth |\n|---|---|\n| POTS telephone | 300 Hz - 3.4 kHz |\n| AM radio | ~100 Hz - 4 kHz (audio bandwidth) |\n| FM radio | 20 Hz - 15 kHz |\n| CD audio | 20 Hz - 20 kHz (44.1 kHz sample rate → Nyquist limit 22.05 kHz) |\n| Professional audio (96 kHz) | 20 Hz - 48 kHz (above hearing) |\n\n### Video Bandwidth\n\nIn analog video, bandwidth determines the horizontal resolution: the higher the bandwidth, the finer the detail the signal can carry. Standard definition NTSC video has a video bandwidth of approximately 4.2 MHz. High-definition analog component video (HDTV) required up to 30 MHz per channel, which drove the shift to digital distribution.\n\n---\n\n## Digital / Network Bandwidth\n\nIn networking and digital AV, bandwidth refers to the maximum data throughput of a link or interface. This usage comes from information theory: Shannon's theorem (1948) showed that the maximum information rate of a channel is proportional to its analog bandwidth - hence the borrowed term.[^1]\n\n### Interface Bandwidth Reference\n\n| Interface | Max bandwidth |\n|---|---|\n| Fast Ethernet (100BASE-TX) | 100 Mbit/s |\n| Gigabit Ethernet | 1,000 Mbit/s (1 Gbit/s) |\n| 10G Ethernet | 10 Gbit/s |\n| USB 2.0 | 480 Mbit/s |\n| HDMI 1.4 | 10.2 Gbit/s |\n| HDMI 2.0 | 18 Gbit/s |\n| HDMI 2.1 | 48 Gbit/s |\n| DisplayPort 2.1 (UHBR20) | 80 Gbit/s |\n| SDI (3G-SDI) | 2.97 Gbit/s |\n| SDI (12G-SDI) | 11.88 Gbit/s |\n\n### Why Bandwidth Matters in AV Design\n\n- **4K at 60 Hz with 4:4:4 color** requires approximately 12 Gbit/s of raw video data - requiring HDMI 2.0 (18 Gbit/s) or DisplayPort 1.4 (32.4 Gbit/s).[^2] HDMI 1.4 (10.2 Gbit/s) can only carry 4K at 30 Hz, or requires chroma subsampling to 4:2:0 at 60 Hz.\n- **AV over IP** streams audio and video as compressed data over Ethernet. Uncompressed 4K at 60 Hz would require ~12 Gbit/s; H.265 compression reduces this to 20-50 Mbit/s for streaming or 1-3 Gbit/s for professional lossless distribution.\n- **Bandwidth reservation** in AVB/TSN networks (see [Audio Video Bridging](/glossary/audio-video-bridging-avb)) allows audio streams to reserve a defined fraction of available Ethernet bandwidth, guaranteeing bounded latency.\n\n---\n\n## History of the Term\n\nThe word \"bandwidth\" entered electrical engineering from radio communications, where it described the range of radio frequencies occupied by a transmitted signal. Early amplitude-modulated (AM) radio occupied a bandwidth of twice the highest audio frequency (a voice signal up to 4 kHz occupies an RF bandwidth of 8 kHz). The term was formalized in the Radio Regulations of the International Telecommunication Union (ITU) in the 1920s-1930s.[^3]\n\nClaude Shannon's 1948 paper \"A Mathematical Theory of Communication\" gave bandwidth its precise mathematical relationship to information capacity (the Shannon-Hartley theorem), which is why the networking community borrowed the term for data rate from the 1960s onward.[^1]\n\n---\n\n[^1]: Shannon, C.E. (July 1948). [\"A Mathematical Theory of Communication\"](https://people.math.harvard.edu/~ctm/home/text/others/shannon/entropy/entropy.pdf) (PDF). *Bell System Technical Journal*. 27 (3): 379-423. doi:10.1002/j.1538-7305.1948.tb01338.x. (Defines channel capacity as a function of bandwidth and signal-to-noise ratio.)\n[^2]: HDMI Forum. [*HDMI Specification 2.0*](https://www.hdmi.org/spec/20). 2013. (Defines 18 Gbit/s aggregate bandwidth; Table of supported video formats at 4K/60 Hz.)\n[^3]: International Telecommunication Union. [\"History of ITU\"](https://www.itu.int/en/history/Pages/ITUsHistory.aspx). ITU. (Background on ITU Radio Regulations development from 1906; bandwidth definitions formalized in international coordination agreements.)"},{"title":"bandwidth","url":"https://sane-av.github.io/glossary/?search=bandwidth","type":"Glossary","snippet":"The available or consumed data communication resources of a communication path, measured in bits per second (bps). It is also called data throughput or bit rate.","tags":["Networking"],"text":"The available or consumed data communication resources of a communication path, measured in bits per second (bps). It is also called data throughput or bit rate."},{"title":"bandwidth limiting","url":"https://sane-av.github.io/glossary/?search=bandwidth%20limiting","type":"Glossary","snippet":"The process of limiting the bandwidth of a signal, usually to allow the signal to be transmitted over a lower-bandwidth path.","tags":["Signal Processing"],"text":"The process of limiting the bandwidth of a signal, usually to allow the signal to be transmitted over a lower-bandwidth path."},{"title":"baseband","url":"https://sane-av.github.io/glossary/?search=baseband","type":"Glossary","snippet":"A signal that has not been modulated onto a higher-frequency carrier.","tags":["General"],"text":"A signal that has not been modulated onto a higher-frequency carrier."},{"title":"bass trap","url":"https://sane-av.github.io/glossary/?search=bass%20trap","type":"Glossary","snippet":"An acoustic energy absorber designed to dampen low-frequency sound energy.","tags":["Acoustics"],"text":"An acoustic energy absorber designed to dampen low-frequency sound energy."},{"title":"benchmarking","url":"https://sane-av.github.io/glossary/?search=benchmarking","type":"Glossary","snippet":"The process of examining methods, techniques, and principles to establish a standard to which comparisons can be made.","tags":["Project Management"],"text":"The process of examining methods, techniques, and principles to establish a standard to which comparisons can be made."},{"title":"bend radius","url":"https://sane-av.github.io/glossary/?search=bend%20radius","type":"Glossary","snippet":"The radial measure of a curve in a cable, conductor, waveguide, or interconnect that defines the physical limit beyond which further bending has a measurable effect on the signal being transported.","tags":["Electrical","Cabling"],"text":"The radial measure of a curve in a cable, conductor, waveguide, or interconnect that defines the physical limit beyond which further bending has a measurable effect on the signal being transported."},{"title":"bi-directional polar pattern","url":"https://sane-av.github.io/glossary/?search=bi-directional%20polar%20pattern","type":"Glossary","snippet":"The shape of the region where some microphones will be most sensitive to sound from the front and rear, while rejecting sound from the top, bottom, and sides.","tags":["Audio"],"text":"The shape of the region where some microphones will be most sensitive to sound from the front and rear, while rejecting sound from the top, bottom, and sides."},{"title":"BOM (bill of materials)","url":"https://sane-av.github.io/glossary/?search=bill%20of%20materials","type":"Glossary","snippet":"A complete equipment list of components that must be procured in order to build the system as specified. The BOM also lists the costs associated with each aspect of designing and implementing the system.","tags":["Project Management"],"text":"A complete equipment list of components that must be procured in order to build the system as specified. The BOM also lists the costs associated with each aspect of designing and implementing the system."},{"title":"bit","url":"https://sane-av.github.io/glossary/?search=bit","type":"Glossary","snippet":"A contraction of the words binary digit. The smallest unit of binary digital information. May have the value 1 or 0.","tags":["General"],"text":"A contraction of the words binary digit. The smallest unit of binary digital information. May have the value 1 or 0."},{"title":"bit depth","url":"https://sane-av.github.io/glossary/?search=bit%20depth","type":"Glossary","snippet":"The number of bits used to specify a parameter.","tags":["Audio"],"text":"The number of bits used to specify a parameter."},{"title":"BER (bit error rate)","url":"https://sane-av.github.io/glossary/?search=bit%20error%20rate","type":"Glossary","snippet":"The number of error bits present in a signal stream per unit of time.","tags":["Networking"],"text":"The number of error bits present in a signal stream per unit of time."},{"title":"bit rate","url":"https://sane-av.github.io/glossary/?search=bit%20rate","type":"Glossary","snippet":"The measurement of the quantity of data transmitted over a digital signal stream. It is measured in bits per second (bps).","tags":["Networking","Signal Processing"],"text":"The measurement of the quantity of data transmitted over a digital signal stream. It is measured in bits per second (bps)."},{"title":"block diagram","url":"https://sane-av.github.io/glossary/?search=block%20diagram","type":"Glossary","snippet":"A diagram of a system or device in which the principal parts are represented by suitably annotated geometrical figures to show both the functions of the parts and their functional relationships.","tags":["General"],"text":"A diagram of a system or device in which the principal parts are represented by suitably annotated geometrical figures to show both the functions of the parts and their functional relationships."},{"title":"Bluetooth","url":"https://sane-av.github.io/glossary/bluetooth/","type":"Glossary","snippet":"A wireless technology for low-cost, short-range radio links between devices. It operates in the 2.402GHz to 2.480GHz industrial, scientific, and medical (ISM) frequency band.","tags":["Networking"],"text":"**Bluetooth** is a short-range wireless technology standard for exchanging data between devices over distances typically up to 10 meters (Class 2) or 100 meters (Class 1), operating in the 2.402-2.480 GHz ISM band using frequency-hopping spread spectrum. It is managed by the Bluetooth Special Interest Group (SIG).\n\nIn AV contexts, Bluetooth is used primarily for wireless audio (headphones, soundbars, hearing aids, wireless microphone accessories), device control (remote controls, room booking panels), and proximity sensing.\n\n## History\n\nDevelopment was initiated in **1989** by Nils Rydbeck, CTO at Ericsson Mobile in Lund, Sweden, with a goal of creating wireless headsets. Principal design was led by Jaap Haartsen and Sven Mattisson at Ericsson.[^1]\n\nThe **Bluetooth SIG** was formally launched in **May 1998** with five founding members: Ericsson, Intel, IBM, Nokia, and Toshiba. The name was proposed by Intel's Jim Kardach, inspired by 10th-century Danish king Harald Bluetooth (Harald Blåtand), who unified disparate Danish tribes - a metaphor for a protocol unifying disparate communication standards.[^2]\n\nThe first commercial Bluetooth product was a wireless headset demonstrated at COMDEX **1999**. The first Bluetooth mobile phone, the Ericsson R520m, shipped in early **2001**.[^3]\n\n## Version History\n\n| Version | Year | Key change |\n|---|---|---|\n| 1.0 | 1999 | Initial release; interoperability problems |\n| 1.1 | 2001 | Ratified as IEEE 802.15.1 |\n| 2.0 + EDR | 2004 | Enhanced Data Rate: up to 3 Mbit/s |\n| 2.1 + EDR | 2007 | Secure Simple Pairing; reduced power in idle |\n| 3.0 + HS | 2009 | High Speed option via 802.11 co-radio (24 Mbit/s) |\n| 4.0 | 2010 | Bluetooth Low Energy (BLE); coin-cell-capable |\n| 4.2 | 2014 | IPv6/IoT support; improved security |\n| 5.0 | 2016 | 4× range, 2× speed for BLE |\n| 5.2 | 2020 | LE Audio; LC3 codec; Auracast broadcast audio |\n| 6.0 | 2024 | Channel Sounding (precision ranging) |\n\n## Audio Profiles and Codecs\n\nThe audio quality of Bluetooth depends on which profile and codec are negotiated between devices:\n\n| Profile / Codec | Bit rate | Notes |\n|---|---|---|\n| HSP / HFP (voice) | ~64 kbit/s | Narrowband voice; telephone quality |\n| A2DP + SBC | ~320 kbit/s | Mandatory codec; lowest quality stereo |\n| A2DP + AAC | ~256 kbit/s | Used by Apple devices |\n| A2DP + aptX | ~352 kbit/s | Qualcomm; CD quality claim |\n| A2DP + aptX HD | ~576 kbit/s | 24-bit audio |\n| A2DP + LDAC | ~990 kbit/s | Sony; near-lossless at max bitrate |\n| LE Audio (LC3) | 160-320 kbit/s | Bluetooth 5.2+; better quality at lower bitrate |\n\n## Latency\n\n**Latency is the primary limitation of Bluetooth audio in AV installations.** Classic Bluetooth A2DP audio introduces 100-200 ms of latency, which causes visible lip-sync issues when used with video. Bluetooth 5.2 LE Audio with LC3 codec targets 20-30 ms minimum latency.[^4]\n\nFor this reason, Bluetooth audio is generally not suitable for:\n- Synchronized playback with video (lip sync fails)\n- Live performance monitoring\n- Any application where the performer or presenter can hear both acoustic sound and Bluetooth audio simultaneously (comb filtering/echo effect)\n\nBluetooth audio is acceptable for:\n- Background music distribution where lip sync is not required\n- Hearing aid streaming (LE Audio hearing aid profile)\n- Assistive listening via Auracast (Bluetooth 5.2+)\n\n## Auracast Broadcast Audio\n\n**Auracast**, introduced with Bluetooth LE Audio (5.2+), enables one device to broadcast audio to an unlimited number of receivers simultaneously - similar to a radio station. In AV, this enables:\n- Assistive listening systems in public venues (replacing or supplementing induction hearing loops)\n- Silent conference / multilingual simultaneous interpretation distribution\n- Fitness club audio (participants tune in with their own hearing aids or Auracast-capable earbuds)\n\nAuracast is expected to become a significant part of assistive listening infrastructure as hearing aid manufacturers adopt LE Audio.[^4]\n\n## AV Installation Considerations\n\n- **2.4 GHz interference:** Bluetooth shares the 2.4 GHz band with Wi-Fi (802.11b/g/n), Zigbee, microwave ovens, and other devices. In high-density environments, Bluetooth audio dropouts are common. Frequency-hopping spread spectrum mitigates but does not eliminate interference.\n- **Pairing management:** In fixed AV installations, Bluetooth is problematic because devices must pair with a specific source. Visitor-owned phones cannot be pre-paired. Auracast addresses this for audio by eliminating the pairing requirement.\n- **Range:** Class 2 Bluetooth (most consumer devices) has a nominal range of 10 m but is significantly reduced by walls, metallic rack enclosures, and human bodies. For reliable room-scale coverage, Class 1 devices or dedicated Bluetooth access points are required.\n\n---\n\n[^1]: European Patent Office. [\"Presenting the economic value of patents nominated for the European Inventor Award 2012 - Jaap Haartsen\"](http://documents.epo.org/projects/babylon/eponet.nsf/0/39F611EACF119B21C12579F30036D7E4/$File/haartsen_en.pdf) (PDF). Technopolis Group. 30 March 2012. (Biography of Jaap Haartsen; documents Ericsson 1989 origin and development timeline.)\n[^2]: Kardach, Jim (5 March 2008). [\"Tech History: How Bluetooth got its name\"](https://www.eetimes.com/tech-history-how-bluetooth-got-its-name). *EE Times*. (First-person account of the naming; Intel's role in the SIG formation.)\n[^3]: Mobile Phone Museum. [\"Ericsson R520m\"](https://www.mobilephonemuseum.com/phone-detail/r520m). Mobile Phone Museum. (Documents the R520m as the first commercially available Bluetooth phone, Q1 2001.)\n[^4]: Bluetooth SIG. [\"Bluetooth LE Audio\"](https://www.bluetooth.com/learn-about-bluetooth/recent-enhancements/le-audio/). Bluetooth Technology Website. 2022. (Specification of LE Audio, LC3 codec, Auracast broadcast audio, and hearing aid support; latency targets cited as 20-30 ms.)"},{"title":"BNC connector","url":"https://sane-av.github.io/glossary/bnc-connector/","type":"Glossary","snippet":"A type of connector featuring a two-pin bayonet-type lock. Available in 75Ω and 50Ω impedances. The most common professional coaxial cable connector because of its reliability and ruggedness. It is used to terminate cables transporting signals such as SDI, RF, video, and time code. Originally named Bayonet Neill-Concelman after its inventors Paul Neill and Carl Concelman.","tags":["Video","Electrical","Cabling"],"text":"The **BNC connector** (Bayonet Neill-Concelman) is a quick-connect/disconnect radio frequency (RF) coaxial connector characterized by two bayonet lugs on the female connector and a quarter-turn locking mechanism. It is the dominant connector for professional video interconnection (SDI), test and measurement equipment, and RF signal distribution.\n\nBNC connectors are manufactured in two impedance versions:\n- **75 Ω** - video and broadcast (SDI, composite, HDTV component)\n- **50 Ω** - RF, data, and test equipment\n\n**The impedance mismatch between the two versions causes signal reflections and return loss degradation.** A 50 Ω BNC connector on a 75 Ω video system will introduce measurable degradation, particularly at SDI frequencies. The two versions are physically identical and mate freely - making incorrect substitution a common installation error.\n\n## History\n\nThe BNC was developed in the late 1940s. It is named after its two inventors:\n\n- **Paul Neill** (Bell Laboratories) - who also developed the N-type connector\n- **Carl Concelman** (Amphenol) - who also developed the C connector (a threaded version of the same basic design)\n\nThe \"Bayonet\" prefix describes the locking mechanism: the same quarter-turn bayonet mount used on British military rifle bayonets and on many camera lens mounts.[^1]\n\nThe BNC was designed as a miniaturized, quick-connect alternative to the larger threaded N-type connector, intended for use at frequencies up to several GHz. Its 50 Ω version became standard in test equipment and data communications (it was the physical connector for 10BASE2 Ethernet in the 1980s). Its 75 Ω version was adopted by the broadcast industry for analog composite video in the 1960s-1970s and has remained the standard video connector through the SDI era.[^2]\n\n## Impedance Versions\n\n| Version | Characteristic impedance | Primary uses |\n|---|---|---|\n| 75 Ω BNC | 75 Ω | SDI video, composite video, component video (YPbPr), AES3 digital audio |\n| 50 Ω BNC | 50 Ω | RF transmission, 10BASE2 Ethernet (obsolete), test equipment, GPS antennas |\n\nThe 75 Ω version maintains 75 Ω impedance through the body of the connector to match the coaxial cable. At SDI frequencies (270 Mbit/s to 11.88 Gbit/s), impedance discontinuities at connectors cause reflections that corrupt the signal. 50 Ω connectors should never be used on 75 Ω video systems.\n\n## Serial Digital Interface (SDI) Applications\n\nBNC is the mandated connector for all SDI signal levels defined by SMPTE:\n\n| Standard | Signal | Data rate |\n|---|---|---|\n| SMPTE 259M | SD-SDI | 270 Mbit/s |\n| SMPTE 292M | HD-SDI | 1.485 Gbit/s |\n| SMPTE 424M | 3G-SDI | 2.97 Gbit/s |\n| SMPTE ST 2081 | 6G-SDI | 5.94 Gbit/s |\n| SMPTE ST 2082 | 12G-SDI | 11.88 Gbit/s |\n\nAt 3G-SDI (2.97 Gbit/s), the analog frequency content at the BNC connector approaches 2 GHz, requiring precision 75 Ω connectors and cables rated for the frequency. Standard-definition connectors and low-quality patch cables become unreliable at HD and 3G frequencies.[^3]\n\n## AES3 Digital Audio (75 Ω variant)\n\nThe AES3 digital audio standard has two physical implementations:\n- **AES3 (balanced)** - 110 Ω impedance on XLR connector (standard in audio equipment)\n- **AES3id (unbalanced)** - 75 Ω impedance on BNC connector (standard in video facilities to route digital audio on video-compatible patch bays)\n\nThe 75 Ω BNC version of AES3 (sometimes called S/PDIF when used in consumer contexts) allows digital audio to share infrastructure with video signals in broadcast facilities.[^4]\n\n## Physical Variants\n\n| Variant | Description |\n|---|---|\n| Standard BNC | Full-size; dominant in professional video |\n| Mini-BNC | Smaller body; used in some rack panels and densely packed patch bays |\n| HD-BNC (DIN 1.0/2.3) | Miniature 75 Ω BNC for high-density 12G-SDI panels |\n| Triaxial (Triax) | Three-conductor BNC variant for camera return and tally in broadcast production |\n\n---\n\n[^1]: Amphenol. [\"History of RF Connector Development\"](https://www.amphenolrf.com/knowledge/rf-connector-history.html). Amphenol RF. (Documents Paul Neill and Carl Concelman as co-inventors; names the BNC from \"Bayonet Neill-Concelman\"; history of Amphenol's role in connector development.)\n[^2]: Whitaker, Jerry C. (2005). [*The Electronics Handbook*](https://www.worldcat.org/isbn/9780849318894), 2nd ed. CRC Press. p. 1456. ISBN 978-0-8493-1889-4. (History of the BNC connector in broadcast engineering; adoption for composite video.)\n[^3]: Society of Motion Picture and Television Engineers. [*SMPTE ST 424:2012 - 3 Gb/s Signal/Data Serial Interface*](https://doi.org/10.5594/SMPTE.ST424.2012). 2012. doi:10.5594/SMPTE.ST424.2012. (Defines 3G-SDI connector and cable requirements; specifies BNC 75 Ω performance at 2.97 Gbit/s.)\n[^4]: AES. [*AES3-2009: AES standard for digital audio - Digital input-output interfacing - Serial transmission format for two-channel linearly represented digital audio data*](https://www.aes.org/publications/standards/search.cfm?docID=14). Audio Engineering Society. 2009. (Defines both the 110 Ω balanced XLR and the 75 Ω unbalanced BNC implementations of the AES3 standard.)"},{"title":"bonding","url":"https://sane-av.github.io/glossary/?search=bonding","type":"Glossary","snippet":"Joining conductive material by a low-impedance connection, thus ensuring that they are at the same electrical potential.","tags":["Electrical"],"text":"Joining conductive material by a low-impedance connection, thus ensuring that they are at the same electrical potential."},{"title":"boundary microphone","url":"https://sane-av.github.io/glossary/?search=boundary%20microphone","type":"Glossary","snippet":"A microphone design where the diaphragm is placed close to a sonic “boundary” such as a wall, ceiling, or other flat surface. This arrangement prevents the acoustic reflections from the surface from mixing with the direct waveform and causing phase distortions. It is used in conference and telepresence systems. Also known as a pressure zone microphone (PZM).","tags":["Acoustics","Audio","Electrical","Systems & Control"],"text":"A microphone design where the diaphragm is placed close to a sonic “boundary” such as a wall, ceiling, or other flat surface. This arrangement prevents the acoustic reflections from the surface from mixing with the direct waveform and causing phase distortions. It is used in conference and telepresence systems. Also known as a pressure zone microphone (PZM)."},{"title":"branch circuit","url":"https://sane-av.github.io/glossary/?search=branch%20circuit","type":"Glossary","snippet":"The circuit conductors between the final overcurrent device protecting the circuit and the load connection.","tags":["Electrical"],"text":"The circuit conductors between the final overcurrent device protecting the circuit and the load connection."},{"title":"breaker box","url":"https://sane-av.github.io/glossary/?search=breaker%20box","type":"Glossary","snippet":"Another name for an electrical load distribution panel. See panelboard.","tags":["Electrical"],"text":"Another name for an electrical load distribution panel. See panelboard."},{"title":"BYOD (bring-your-own-device)","url":"https://sane-av.github.io/glossary/?search=bring-your-own-device","type":"Glossary","snippet":"An approach that allows users to access resources such as a network with personal devices.","tags":["Systems & Control"],"text":"An approach that allows users to access resources such as a network with personal devices."},{"title":"broadcast domain","url":"https://sane-av.github.io/glossary/?search=broadcast%20domain","type":"Glossary","snippet":"A set of devices that can send Data Link-layer (layer 2) frames to each other directly, without passing through a Network-layer (layer 3) device. Broadcast traffic sent by one device in a broadcast domain is received by all devices in the domain.","tags":["Networking"],"text":"A set of devices that can send Data Link-layer (layer 2) frames to each other directly, without passing through a Network-layer (layer 3) device. Broadcast traffic sent by one device in a broadcast domain is received by all devices in the domain."},{"title":"buffer amplifier","url":"https://sane-av.github.io/glossary/?search=buffer%20amplifier","type":"Glossary","snippet":"An electronic device that provides isolation and some load independence between circuit components.","tags":["Audio","Electrical","Signal Processing"],"text":"An electronic device that provides isolation and some load independence between circuit components."},{"title":"BIM (building information modeling)","url":"https://sane-av.github.io/glossary/?search=building%20information%20modeling","type":"Glossary","snippet":"A data repository for building design, construction, and maintenance data shared by multiple disciplines on a single project.","tags":["Systems & Control","Project Management"],"text":"A data repository for building design, construction, and maintenance data shared by multiple disciplines on a single project."},{"title":"bus","url":"https://sane-av.github.io/glossary/?search=bus","type":"Glossary","snippet":"A wiring system that links multiple devices.","tags":["Electrical","Cabling"],"text":"A wiring system that links multiple devices."},{"title":"busbar","url":"https://sane-av.github.io/glossary/?search=busbar","type":"Glossary","snippet":"An electrically conductive path that serves as a common connection for two or more circuits.","tags":["Electrical"],"text":"An electrically conductive path that serves as a common connection for two or more circuits."},{"title":"buzz","url":"https://sane-av.github.io/glossary/?search=buzz","type":"Glossary","snippet":"A noise generated by the higher-order harmonics of the hum (50Hz or 60Hz) generated by the electrical mains.","tags":["Audio"],"text":"A noise generated by the higher-order harmonics of the hum (50Hz or 60Hz) generated by the electrical mains."},{"title":"byte","url":"https://sane-av.github.io/glossary/?search=byte","type":"Glossary","snippet":"A data word containing 8 bits, also known as an octet. The symbol for byte is B.","tags":["General"],"text":"A data word containing 8 bits, also known as an octet. The symbol for byte is B."},{"title":"cable","url":"https://sane-av.github.io/glossary/?search=cable","type":"Glossary","snippet":"An assembly of more than one signal carrier (wire or optical fiber).","tags":["Cabling"],"text":"An assembly of more than one signal carrier (wire or optical fiber)."},{"title":"cable tray","url":"https://sane-av.github.io/glossary/?search=cable%20tray","type":"Glossary","snippet":"A structure to provide rigid continuous support for cables.","tags":["Cabling"],"text":"A structure to provide rigid continuous support for cables."},{"title":"CAN (campus area network)","url":"https://sane-av.github.io/glossary/?search=campus%20area%20network","type":"Glossary","snippet":"A type of network linking multiple LANs in a limited geographical area such as a university campus or a cluster of buildings.","tags":["Networking"],"text":"A type of network linking multiple LANs in a limited geographical area such as a university campus or a cluster of buildings."},{"title":"candela","url":"https://sane-av.github.io/glossary/?search=candela","type":"Glossary","snippet":"The unit of luminous intensity. A candela is the luminous intensity emitted by a reference point light source in a given direction. The symbol for candela is cd. By sheer “coincidence,” the luminous intensity of a common wax candle is approximately 1 candela.","tags":["Lighting"],"text":"The unit of luminous intensity. A candela is the luminous intensity emitted by a reference point light source in a given direction. The symbol for candela is cd. By sheer “coincidence,” the luminous intensity of a common wax candle is approximately 1 candela."},{"title":"cannon connector","url":"https://sane-av.github.io/glossary/?search=cannon%20connector","type":"Glossary","snippet":"An alternative name for the XLR family of latching, low-voltage connectors used in professional audiovisual systems. The three-pin version is the standard audio signal cable for the production and AV in dustries. The four-pin version is widely used for communication headsets, and the five-pin version is the standard connector for the DMX512 digital lighting protocol.","tags":["Audio","Electrical","Cabling","Lighting"],"text":"An alternative name for the XLR family of latching, low-voltage connectors used in professional audiovisual systems. The three-pin version is the standard audio signal cable for the production and AV in dustries. The four-pin version is widely used for communication headsets, and the five-pin version is the standard connector for the DMX512 digital lighting protocol."},{"title":"capacitance","url":"https://sane-av.github.io/glossary/?search=capacitance","type":"Glossary","snippet":"The ability of a material to store an electrical charge. Capacitance is measured in farads (F). The symbol for capacitance is C.","tags":["Electrical"],"text":"The ability of a material to store an electrical charge. Capacitance is measured in farads (F). The symbol for capacitance is C."},{"title":"XC (capacitive reactance)","url":"https://sane-av.github.io/glossary/?search=capacitive%20reactance","type":"Glossary","snippet":"The opposition a capacitive device offers to alternating current flow. It is measured in ohms (Ω). The symbol for capacitive reactance is XC . Capacitive reactance is inversely proportional to the frequency of the current in a circuit.","tags":["Electrical"],"text":"The opposition a capacitive device offers to alternating current flow. It is measured in ohms (Ω). The symbol for capacitive reactance is XC . Capacitive reactance is inversely proportional to the frequency of the current in a circuit."},{"title":"capacitor","url":"https://sane-av.github.io/glossary/?search=capacitor","type":"Glossary","snippet":"A passive electrical component used to store electric charge. Constructed from electrodes of conductive material separated by a dielectric.","tags":["Electrical"],"text":"A passive electrical component used to store electric charge. Constructed from electrodes of conductive material separated by a dielectric."},{"title":"captive screw connector","url":"https://sane-av.github.io/glossary/?search=captive%20screw%20connector","type":"Glossary","snippet":"Also known as a Euroblock or Phoenix connector. A termination method where a stripped wire is inserted into the connector and secured by a set screw that pushes down a gate to form the electrical bond and clamp the wire in place.","tags":["Cabling"],"text":"Also known as a Euroblock or Phoenix connector. A termination method where a stripped wire is inserted into the connector and secured by a set screw that pushes down a gate to form the electrical bond and clamp the wire in place."},{"title":"cardioid polar pattern","url":"https://sane-av.github.io/glossary/?search=cardioid%20polar%20pattern","type":"Glossary","snippet":"A heart-shaped region where some microphones will be most sensitive to sound predominately from the front of the microphone diaphragm and reject sound coming from the sides and rear.","tags":["Audio"],"text":"A heart-shaped region where some microphones will be most sensitive to sound predominately from the front of the microphone diaphragm and reject sound coming from the sides and rear."},{"title":"carrier","url":"https://sane-av.github.io/glossary/?search=carrier","type":"Glossary","snippet":"Modulated frequency that carries a communication signal.","tags":["General"],"text":"Modulated frequency that carries a communication signal."},{"title":"Category 5 (Cat 5)","url":"https://sane-av.github.io/glossary/?search=Category%205%20(Cat%205)","type":"Glossary","snippet":"The designation for 100Ω unshielded twisted-pair (UTP) cables and associated connecting hardware whose characteristics are specified for data transmission up to 100Mbps (part of the EIA/TIA 568A standard).","tags":["Cabling","Standards"],"text":"The designation for 100Ω unshielded twisted-pair (UTP) cables and associated connecting hardware whose characteristics are specified for data transmission up to 100Mbps (part of the EIA/TIA 568A standard)."},{"title":"Category 5e (Cat 5e)","url":"https://sane-av.github.io/glossary/?search=Category%205e%20(Cat%205e)","type":"Glossary","snippet":"An enhanced version of the Cat 5 UTP cable standard that adds specifications to reduce far-end crosstalk for data transmission up to 1Gbps (part of the EIA/TIA 568A standard).","tags":["Cabling","Signal Processing","Standards"],"text":"An enhanced version of the Cat 5 UTP cable standard that adds specifications to reduce far-end crosstalk for data transmission up to 1Gbps (part of the EIA/TIA 568A standard)."},{"title":"Category 6 (Cat 6)","url":"https://sane-av.github.io/glossary/?search=Category%206%20(Cat%206)","type":"Glossary","snippet":"A UTP cable standard for Gigabit Ethernet and other interconnections that is backward-compatible with Cat 5, Cat 5e, and Cat 3 cable (part of the EIA/TIA 568A standard). Cat 6 features more stringent specifications for crosstalk and system noise.","tags":["Networking","Cabling","Signal Processing","Standards"],"text":"A UTP cable standard for Gigabit Ethernet and other interconnections that is backward-compatible with Cat 5, Cat 5e, and Cat 3 cable (part of the EIA/TIA 568A standard). Cat 6 features more stringent specifications for crosstalk and system noise."},{"title":"Category 6A (Cat 6A)","url":"https://sane-av.github.io/glossary/?search=Category%206A%20(Cat%206A)","type":"Glossary","snippet":"A twisted-pair cable standard for 10 Gigabit Ethernet and other interconnections that is backward-compatible with Cat 5, Cat 5e, and Cat 6 cable. Constructed using a mechanism to physically separate the twisted-pairs, Cat 6A features more stringent specifications for alien and near-end crosstalk.","tags":["Networking","Cabling","Signal Processing"],"text":"A twisted-pair cable standard for 10 Gigabit Ethernet and other interconnections that is backward-compatible with Cat 5, Cat 5e, and Cat 6 cable. Constructed using a mechanism to physically separate the twisted-pairs, Cat 6A features more stringent specifications for alien and near-end crosstalk."},{"title":"Category 7 (Cat 7)","url":"https://sane-av.github.io/glossary/?search=Category%207%20(Cat%207)","type":"Glossary","snippet":"A twisted-pair cable standard for 10 Gigabit Ethernet and other interconnections that is backward-compatible with Cat 5e and Cat 6A cable. To further reduce crosstalk, in Cat 7 cables, each twisted-pair is shielded and the entire cable is shielded.","tags":["Networking","Cabling","Signal Processing"],"text":"A twisted-pair cable standard for 10 Gigabit Ethernet and other interconnections that is backward-compatible with Cat 5e and Cat 6A cable. To further reduce crosstalk, in Cat 7 cables, each twisted-pair is shielded and the entire cable is shielded."},{"title":"Category 8 (Cat 8)","url":"https://sane-av.github.io/glossary/?search=Category%208%20(Cat%208)","type":"Glossary","snippet":"A twisted-pair cable standard for 40 Gigabit Ethernet and other interconnections that is backward-compatible with Cat 5e, Cat 6, and Cat 6A cable (part of the EIA/TIA 568A standard). Cat 8 features a shield around each twisted-pair and a further shield enclosing all twisted-pairs. It is only specified at 40Gbps for runs up to 30m (100ft).","tags":["Networking","Cabling","Standards"],"text":"A twisted-pair cable standard for 40 Gigabit Ethernet and other interconnections that is backward-compatible with Cat 5e, Cat 6, and Cat 6A cable (part of the EIA/TIA 568A standard). Cat 8 features a shield around each twisted-pair and a further shield enclosing all twisted-pairs. It is only specified at 40Gbps for runs up to 30m (100ft)."},{"title":"CRT (cathode ray tube)","url":"https://sane-av.github.io/glossary/?search=cathode%20ray%20tube","type":"Glossary","snippet":"A high-vacuum glass tube containing an electron gun to produce the images seen on the phosphorcoated face of the tube. This video display technology was used in early-generation video monitors, television receivers, radar displays, and oscilloscopes.","tags":["Video","Lighting"],"text":"A high-vacuum glass tube containing an electron gun to produce the images seen on the phosphorcoated face of the tube. This video display technology was used in early-generation video monitors, television receivers, radar displays, and oscilloscopes."},{"title":"CATV","url":"https://sane-av.github.io/glossary/?search=CATV","type":"Glossary","snippet":"Community antenna television. A system where broadcast television signals are received by a single central antenna and distributed to multiple end users.","tags":["Networking"],"text":"Community antenna television. A system where broadcast television signals are received by a single central antenna and distributed to multiple end users."},{"title":"center tap","url":"https://sane-av.github.io/glossary/?search=center%20tap","type":"Glossary","snippet":"A connection point located halfway along the track or winding of an electronic device such as an inductor or resistor.","tags":["General"],"text":"A connection point located halfway along the track or winding of an electronic device such as an inductor or resistor."},{"title":"central cluster","url":"https://sane-av.github.io/glossary/?search=central%20cluster","type":"Glossary","snippet":"A single-source configuration of loudspeakers. In a central cluster, the sound is perceived as coming from one point in the room. The central cluster is normally located directly above (on the proscenium) and slightly in front of the primary microphone location.","tags":["Audio"],"text":"A single-source configuration of loudspeakers. In a central cluster, the sound is perceived as coming from one point in the room. The central cluster is normally located directly above (on the proscenium) and slightly in front of the primary microphone location."},{"title":"CPU (central processing unit)","url":"https://sane-av.github.io/glossary/?search=central%20processing%20unit","type":"Glossary","snippet":"The portion of a computer system that reads and executes commands.","tags":["General"],"text":"The portion of a computer system that reads and executes commands."},{"title":"CCD (charged-coupled device)","url":"https://sane-av.github.io/glossary/?search=charged-coupled%20device","type":"Glossary","snippet":"A light-sensitive semiconductor device, commonly used in video and digital cameras, that converts optical images into electronic signals.","tags":["Video","Electrical","Cabling"],"text":"A light-sensitive semiconductor device, commonly used in video and digital cameras, that converts optical images into electronic signals."},{"title":"chassis","url":"https://sane-av.github.io/glossary/?search=chassis","type":"Glossary","snippet":"Also called a cabinet or frame, an enclosure that houses electronic equipment and is frequently electrically conductive (metal). The conductive enclosure acts as a Faraday cage/shield and is connected to the safety-grounding conductor of the AC power supply to provide protection against electric shock.","tags":["Electrical","Cabling"],"text":"Also called a cabinet or frame, an enclosure that houses electronic equipment and is frequently electrically conductive (metal). The conductive enclosure acts as a Faraday cage/shield and is connected to the safety-grounding conductor of the AC power supply to provide protection against electric shock."},{"title":"chassis ground","url":"https://sane-av.github.io/glossary/?search=chassis%20ground","type":"Glossary","snippet":"A 0V (zero volt) connection point of any electrically conductive chassis or enclosure surrounding an electronic device. This connection point may be extended to the earth/ground.","tags":["Electrical"],"text":"A 0V (zero volt) connection point of any electrically conductive chassis or enclosure surrounding an electronic device. This connection point may be extended to the earth/ground."},{"title":"chroma","url":"https://sane-av.github.io/glossary/?search=chroma","type":"Glossary","snippet":"The saturation, or intensity, of a specific color. It is one of the three attributes that define a color; the other two are hue and value or luminance.","tags":["Video"],"text":"The saturation, or intensity, of a specific color. It is one of the three attributes that define a color; the other two are hue and value or luminance."},{"title":"chrominance","url":"https://sane-av.github.io/glossary/?search=chrominance","type":"Glossary","snippet":"The color component of a composite or S-video signal.","tags":["Video"],"text":"The color component of a composite or S-video signal."},{"title":"Classless Inter-Domain Routing notation","url":"https://sane-av.github.io/glossary/?search=Classless%20Inter-Domain%20Routing%20notation","type":"Glossary","snippet":"A compact representation of an IP address and its subnet mask using a slash and a decimal number to indicate how many leading 1 bits are in the network mask, with the remaining bits being the network host identifiers (e.g., 192.168.220.16/24). The subnet mask of 255.255.255.0 (24 mask bits) is represented as /24 in CIDR notation. CIDR replaces the class designations (A, B, and C) for IP address ranges.","tags":["Networking"],"text":"A compact representation of an IP address and its subnet mask using a slash and a decimal number to indicate how many leading 1 bits are in the network mask, with the remaining bits being the network host identifiers (e.g., 192.168.220.16/24). The subnet mask of 255.255.255.0 (24 mask bits) is represented as /24 in CIDR notation. CIDR replaces the class designations (A, B, and C) for IP address ranges."},{"title":"cliff effect","url":"https://sane-av.github.io/glossary/?search=cliff%20effect","type":"Glossary","snippet":"The sudden loss of digital signal reception. When a digital signal is attenuated to the point where signal for a digital 1 is indistinguishable from the signal for a digital 0.","tags":["Signal Processing"],"text":"The sudden loss of digital signal reception. When a digital signal is attenuated to the point where signal for a digital 1 is indistinguishable from the signal for a digital 0."},{"title":"clipping","url":"https://sane-av.github.io/glossary/?search=clipping","type":"Glossary","snippet":"The distortion of a signal when a device’s peak amplitude is exceeded.","tags":["Signal Processing"],"text":"The distortion of a signal when a device’s peak amplitude is exceeded."},{"title":"clock adjustment","url":"https://sane-av.github.io/glossary/?search=clock%20adjustment","type":"Glossary","snippet":"The process used to align the timing of digital signals between devices.","tags":["Signal Processing"],"text":"The process used to align the timing of digital signals between devices."},{"title":"CMOS","url":"https://sane-av.github.io/glossary/?search=CMOS","type":"Glossary","snippet":"Complementary metal oxide semiconductor is a semiconductor fabrication process that uses symmetrical pairs of complementary p-type and n-type field effect transistors (FETs) for logic functions. CMOS devices have high noise immunity and draw low current in a static state. This technology is extensively used in the production of digital electronic devices, including camera pickup chips.","tags":["Electrical"],"text":"Complementary metal oxide semiconductor is a semiconductor fabrication process that uses symmetrical pairs of complementary p-type and n-type field effect transistors (FETs) for logic functions. CMOS devices have high noise immunity and draw low current in a static state. This technology is extensively used in the production of digital electronic devices, including camera pickup chips."},{"title":"coaxial cable","url":"https://sane-av.github.io/glossary/?search=coaxial%20cable","type":"Glossary","snippet":"A cable consisting of a center conductor surrounded by insulating material, concentric outer conductor, and optional protective covering, all of circular cross section.","tags":["Electrical","Cabling"],"text":"A cable consisting of a center conductor surrounded by insulating material, concentric outer conductor, and optional protective covering, all of circular cross section."},{"title":"CobraNet","url":"https://sane-av.github.io/glossary/?search=CobraNet","type":"Glossary","snippet":"CobraNet is a proprietary digital audio Data Link-layer (layer 2) protocol designed by Cirrus Logic. It uses standard Fast Ethernet cabling, switches, and other components. CobraNet signals are nonroutable.","tags":["Audio","Networking"],"text":"CobraNet is a proprietary digital audio Data Link-layer (layer 2) protocol designed by Cirrus Logic. It uses standard Fast Ethernet cabling, switches, and other components. CobraNet signals are nonroutable."},{"title":"codec","url":"https://sane-av.github.io/glossary/?search=codec","type":"Glossary","snippet":"A contraction of the term coder/decoder. An electronic device or software process that encodes or decodes a data stream for transmission and reception over a communications medium.","tags":["General"],"text":"A contraction of the term coder/decoder. An electronic device or software process that encodes or decodes a data stream for transmission and reception over a communications medium."},{"title":"collision domain","url":"https://sane-av.github.io/glossary/?search=collision%20domain","type":"Glossary","snippet":"A set of devices on a carrier-sense multiple access (CSMA) local area network whose packets may collide with one another if they transmit data at the same time. Only found in nonswitched Ethernet networks.","tags":["Networking"],"text":"A set of devices on a carrier-sense multiple access (CSMA) local area network whose packets may collide with one another if they transmit data at the same time. Only found in nonswitched Ethernet networks."},{"title":"color difference signal","url":"https://sane-av.github.io/glossary/?search=color%20difference%20signal","type":"Glossary","snippet":"A signal that conveys color information such as hue and saturation in a composite format. Two such signals are needed. These color difference signals are R-Y and B-Y. Sometimes referred to as Pr and Pb or Cr and Cb.","tags":["Video"],"text":"A signal that conveys color information such as hue and saturation in a composite format. Two such signals are needed. These color difference signals are R-Y and B-Y. Sometimes referred to as Pr and Pb or Cr and Cb."},{"title":"CRI (color rendering index)","url":"https://sane-av.github.io/glossary/?search=color%20rendering%20index","type":"Glossary","snippet":"The effect a light source has on the perceived color of objects indexed against an incandescent source (CRI 100) of the same correlated color temperature.","tags":["Video","Lighting"],"text":"The effect a light source has on the perceived color of objects indexed against an incandescent source (CRI 100) of the same correlated color temperature."},{"title":"color space","url":"https://sane-av.github.io/glossary/?search=color%20space","type":"Glossary","snippet":"A color space is the range of spectral colors that can be interpreted or displayed by a device. The range is usually identified by being mapped against an area on the CIE chromaticity diagram. A range of wellknown color spaces is used in imaging and display.","tags":["Video"],"text":"A color space is the range of spectral colors that can be interpreted or displayed by a device. The range is usually identified by being mapped against an area on the CIE chromaticity diagram. A range of wellknown color spaces is used in imaging and display."},{"title":"color temperature","url":"https://sane-av.github.io/glossary/?search=color%20temperature","type":"Glossary","snippet":"The quantification of the color of “white” light in reference to the light emitted by a standardized object at a specified temperature on the Kelvin scale. Measured in kelvins (K). Low color temperature light (~2,000K) has a warm (reddish) look, while light with a high color temperature (>4,000K) has a colder (bluish) appearance.","tags":["Video"],"text":"The quantification of the color of “white” light in reference to the light emitted by a standardized object at a specified temperature on the Kelvin scale. Measured in kelvins (K). Low color temperature light (~2,000K) has a warm (reddish) look, while light with a high color temperature (>4,000K) has a colder (bluish) appearance."},{"title":"combiner","url":"https://sane-av.github.io/glossary/?search=combiner","type":"Glossary","snippet":"A device or process that combines signals of different frequencies together in a single medium. Used to combine multiple RF television signals into one cable for use in broadband cable television distribution.","tags":["Cabling","Signal Processing"],"text":"A device or process that combines signals of different frequencies together in a single medium. Used to combine multiple RF television signals into one cable for use in broadband cable television distribution."},{"title":"common mode","url":"https://sane-av.github.io/glossary/?search=common%20mode","type":"Glossary","snippet":"1. Voltage fed in phase to both inputs of a differential amplifier. 2. The signal voltage that appears equally and in phase from each current carrying conductor to ground.","tags":["Audio","Electrical","Signal Processing"],"text":"1. Voltage fed in phase to both inputs of a differential amplifier. 2. The signal voltage that appears equally and in phase from each current carrying conductor to ground."},{"title":"CMRR (common-mode rejection ratio)","url":"https://sane-av.github.io/glossary/?search=common-mode%20rejection%20ratio","type":"Glossary","snippet":"The ratio of the differential voltage gain to the common-mode voltage gain; expressed in decibels.","tags":["Audio","Electrical","Signal Processing"],"text":"The ratio of the differential voltage gain to the common-mode voltage gain; expressed in decibels."},{"title":"compander","url":"https://sane-av.github.io/glossary/?search=compander","type":"Glossary","snippet":"An audio processing device that combines compression and expansion.","tags":["Audio"],"text":"An audio processing device that combines compression and expansion."},{"title":"component video","url":"https://sane-av.github.io/glossary/?search=component%20video","type":"Glossary","snippet":"Color video in which the brightness (luminance), color hue, and saturation (chrominance) are handled independently. The red, green, and blue signals - or, more commonly, the Y, R-Y, and B-Y signals - are encoded onto three wires.","tags":["Video","Signal Processing"],"text":"Color video in which the brightness (luminance), color hue, and saturation (chrominance) are handled independently. The red, green, and blue signals - or, more commonly, the Y, R-Y, and B-Y signals - are encoded onto three wires."},{"title":"composite video signal","url":"https://sane-av.github.io/glossary/?search=composite%20video%20signal","type":"Glossary","snippet":"A single video signal that carries the complete color picture information and all synchronization signals.","tags":["Video"],"text":"A single video signal that carries the complete color picture information and all synchronization signals."},{"title":"compression","url":"https://sane-av.github.io/glossary/?search=compression","type":"Glossary","snippet":"1. An increase in density and pressure in a compressible medium such as air. 2. A process that reduces data size.","tags":["General"],"text":"1. An increase in density and pressure in a compressible medium such as air. 2. A process that reduces data size."},{"title":"compression ratio","url":"https://sane-av.github.io/glossary/?search=compression%20ratio","type":"Glossary","snippet":"1. How much the volume on an audio compressor reduces depending on how far above the threshold the signal is. 2. The ratio in size between the original signal and its compressed form.","tags":["Audio"],"text":"1. How much the volume on an audio compressor reduces depending on how far above the threshold the signal is. 2. The ratio in size between the original signal and its compressed form."},{"title":"compressor","url":"https://sane-av.github.io/glossary/?search=compressor","type":"Glossary","snippet":"A device that controls the overall amplitude of a signal by reducing the part of the signal that exceeds an adjustable threshold level set by the user. When the signal exceeds the threshold level, the overall amplitude is reduced by a ratio, also usually adjustable by the user.","tags":["Audio"],"text":"A device that controls the overall amplitude of a signal by reducing the part of the signal that exceeds an adjustable threshold level set by the user. When the signal exceeds the threshold level, the overall amplitude is reduced by a ratio, also usually adjustable by the user."},{"title":"compressor threshold","url":"https://sane-av.github.io/glossary/?search=compressor%20threshold","type":"Glossary","snippet":"Sets the point at which the automatic volume reduction kicks in. When the input goes above the threshold, an audio compressor automatically reduces the volume to keep the signal from getting too loud.","tags":["Audio"],"text":"Sets the point at which the automatic volume reduction kicks in. When the input goes above the threshold, an audio compressor automatically reduces the volume to keep the signal from getting too loud."},{"title":"condenser microphone","url":"https://sane-av.github.io/glossary/?search=condenser%20microphone","type":"Glossary","snippet":"Also called a capacitor microphone, a microphone that transduces sound into an electric current using capacitive principles.","tags":["Audio","Electrical"],"text":"Also called a capacitor microphone, a microphone that transduces sound into an electric current using capacitive principles."},{"title":"conductor","url":"https://sane-av.github.io/glossary/?search=conductor","type":"Glossary","snippet":"In electronics, a material that easily conducts an electric current because some electrons in the material are easy to move.","tags":["Electrical"],"text":"In electronics, a material that easily conducts an electric current because some electrons in the material are easy to move."},{"title":"conduit","url":"https://sane-av.github.io/glossary/?search=conduit","type":"Glossary","snippet":"A circular tube that houses cable.","tags":["Cabling"],"text":"A circular tube that houses cable."},{"title":"cone","url":"https://sane-av.github.io/glossary/?search=cone","type":"Glossary","snippet":"A lightweight, semi-rigid, conical diaphragm structure attached to the voice coil of a loudspeaker.","tags":["Audio"],"text":"A lightweight, semi-rigid, conical diaphragm structure attached to the voice coil of a loudspeaker."},{"title":"constant voltage distribution","url":"https://sane-av.github.io/glossary/?search=constant%20voltage%20distribution","type":"Glossary","snippet":"25V, 70V, 100V; a method of distributing signals to loudspeakers over a large area with lower losses than typical direct-coupled connections. Also known as a high-impedance distribution system.","tags":["Audio","Electrical"],"text":"25V, 70V, 100V; a method of distributing signals to loudspeakers over a large area with lower losses than typical direct-coupled connections. Also known as a high-impedance distribution system."},{"title":"CEC (Consumer Electronic Control)","url":"https://sane-av.github.io/glossary/?search=Consumer%20Electronic%20Control","type":"Glossary","snippet":"A single-wire, bi-directional serial bus that uses AV link protocols to perform remote-control functions. It is an optional feature of the HDMI specification that allows for system-level automation when all devices in an AV system support it.","tags":["Video","Electrical","Cabling","Systems & Control"],"text":"A single-wire, bi-directional serial bus that uses AV link protocols to perform remote-control functions. It is an optional feature of the HDMI specification that allows for system-level automation when all devices in an AV system support it."},{"title":"contact closure","url":"https://sane-av.github.io/glossary/?search=contact%20closure","type":"Glossary","snippet":"A simple signaling system based on whether a contact or switch is open or closed. The conventional protocol is to interpret a closed contact (on) as a binary 1 and an open contact (off) as a binary 0.","tags":["Signal Processing"],"text":"A simple signaling system based on whether a contact or switch is open or closed. The conventional protocol is to interpret a closed contact (on) as a binary 1 and an open contact (off) as a binary 0."},{"title":"contactor","url":"https://sane-av.github.io/glossary/?search=contactor","type":"Glossary","snippet":"An electrically controlled switch used for switching a power circuit, similar to a relay, but with higher switched-current ratings. May be single-pole or multipole.","tags":["Electrical"],"text":"An electrically controlled switch used for switching a power circuit, similar to a relay, but with higher switched-current ratings. May be single-pole or multipole."},{"title":"CDN (content delivery network)","url":"https://sane-av.github.io/glossary/?search=content%20delivery%20network","type":"Glossary","snippet":"A distributed network of caching servers that can provide hosted unicast distribution of media for an organization. They are most often utilized by organizations whose content is in high demand.","tags":["Networking"],"text":"A distributed network of caching servers that can provide hosted unicast distribution of media for an organization. They are most often utilized by organizations whose content is in high demand."},{"title":"contrast","url":"https://sane-av.github.io/glossary/?search=contrast","type":"Glossary","snippet":"The difference in luminance between dark and light elements of an image.","tags":["Video"],"text":"The difference in luminance between dark and light elements of an image."},{"title":"contrast ratio","url":"https://sane-av.github.io/glossary/?search=contrast%20ratio","type":"Glossary","snippet":"Describes the dynamic video range of a display device as a numeric relationship between the brightest color (typically white) and the darkest color (typically black) that the system is capable of producing. Two methods are used to specify contrast ratio; the full on/full off method describes the dynamic contrast ratio, and the ANSI method measures the static contrast ratio.","tags":["Video","Standards"],"text":"Describes the dynamic video range of a display device as a numeric relationship between the brightest color (typically white) and the darkest color (typically black) that the system is capable of producing. Two methods are used to specify contrast ratio; the full on/full off method describes the dynamic contrast ratio, and the ANSI method measures the static contrast ratio."},{"title":"control system","url":"https://sane-av.github.io/glossary/?search=control%20system","type":"Glossary","snippet":"A system that controls subsystems such as audio, video, winches, drapes, mechanical devices, lighting, and atmospheric effects.","tags":["Audio","Video","Systems & Control"],"text":"A system that controls subsystems such as audio, video, winches, drapes, mechanical devices, lighting, and atmospheric effects."},{"title":"CCT (correlated color temperature)","url":"https://sane-av.github.io/glossary/?search=correlated%20color%20temperature","type":"Glossary","snippet":"The color appearance of a light source as compared with a standardized object heated to a temperature measured on the Kelvin scale. CCT is measured kelvins (K).","tags":["Video","Lighting"],"text":"The color appearance of a light source as compared with a standardized object heated to a temperature measured on the Kelvin scale. CCT is measured kelvins (K)."},{"title":"coverage pattern","url":"https://sane-av.github.io/glossary/?search=coverage%20pattern","type":"Glossary","snippet":"The pattern of sound energy that a loudspeaker emits. The coverage pattern is dependent on the frequency of the sounds and the dimensions of the loudspeaker.","tags":["Audio"],"text":"The pattern of sound energy that a loudspeaker emits. The coverage pattern is dependent on the frequency of the sounds and the dimensions of the loudspeaker."},{"title":"critical distance (d c)","url":"https://sane-av.github.io/glossary/?search=critical%20distance%20(d%20c)","type":"Glossary","snippet":"The point where the sound pressure level of the direct and reverberant sound fields is equal.","tags":["Acoustics"],"text":"The point where the sound pressure level of the direct and reverberant sound fields is equal."},{"title":"critical path schedule","url":"https://sane-av.github.io/glossary/?search=critical%20path%20schedule","type":"Glossary","snippet":"A scheduling methodology that reveals the interdependence of activities and assesses resource and time requirements and trade-offs. It also determines the project’s completion date and provides the capability to evaluate activity performance.","tags":["Project Management"],"text":"A scheduling methodology that reveals the interdependence of activities and assesses resource and time requirements and trade-offs. It also determines the project’s completion date and provides the capability to evaluate activity performance."},{"title":"crossover","url":"https://sane-av.github.io/glossary/?search=crossover","type":"Glossary","snippet":"An electronic device that separates the frequency bands of an audio signal so that each driver in a multidriver loudspeaker system is sent only those frequencies that it will transduce accurately.","tags":["Audio"],"text":"An electronic device that separates the frequency bands of an audio signal so that each driver in a multidriver loudspeaker system is sent only those frequencies that it will transduce accurately."},{"title":"crosspoint","url":"https://sane-av.github.io/glossary/?search=crosspoint","type":"Glossary","snippet":"A matrix-based switching device with multiple inputs and outputs wherein any input may be connected to any, many, or all outputs.","tags":["Signal Processing"],"text":"A matrix-based switching device with multiple inputs and outputs wherein any input may be connected to any, many, or all outputs."},{"title":"crosstalk","url":"https://sane-av.github.io/glossary/?search=crosstalk","type":"Glossary","snippet":"Any phenomenon by which a signal transmitted on one circuit or channel of a transmission system creates an undesired effect in another circuit or channel.","tags":["Electrical","Signal Processing"],"text":"Any phenomenon by which a signal transmitted on one circuit or channel of a transmission system creates an undesired effect in another circuit or channel."},{"title":"current","url":"https://sane-av.github.io/glossary/?search=current","type":"Glossary","snippet":"The quantity of electrical charge flowing in a circuit, measured in amperes (A). The symbol for current is I.","tags":["Electrical"],"text":"The quantity of electrical charge flowing in a circuit, measured in amperes (A). The symbol for current is I."},{"title":"curvature of field","url":"https://sane-av.github.io/glossary/?search=curvature%20of%20field","type":"Glossary","snippet":"A blurry appearance around the edge of an otherwise in-focus object (or the reverse) when the angle incidence of light passing through the edges of a lens is different from the angle of incidence at the center of the surface. Curvature of field is due to the shape of the lens.","tags":["Video"],"text":"A blurry appearance around the edge of an otherwise in-focus object (or the reverse) when the angle incidence of light passing through the edges of a lens is different from the angle of incidence at the center of the surface. Curvature of field is due to the shape of the lens."},{"title":"cybersecurity","url":"https://sane-av.github.io/glossary/?search=cybersecurity","type":"Glossary","snippet":"A process or capability intended to protect information and communications systems against unauthorized use or modification, as well as against damage and exploitation. This includes policies, strategies, and standards regarding the security and operations of these systems.","tags":["Security"],"text":"A process or capability intended to protect information and communications systems against unauthorized use or modification, as well as against damage and exploitation. This includes policies, strategies, and standards regarding the security and operations of these systems."},{"title":"Dante","url":"https://sane-av.github.io/glossary/?search=Dante","type":"Glossary","snippet":"A proprietary digital audio Network-layer (layer 3) protocol created by Audinate. Dante sends audio and video information as Internet Protocol (IP) packets. It is fully routable over IP networks using standard Ethernet switches, routers, and other components. Dante controller software manages data prioritization and signal routes.","tags":["Audio","Video","Networking"],"text":"A proprietary digital audio Network-layer (layer 3) protocol created by Audinate. Dante sends audio and video information as Internet Protocol (IP) packets. It is fully routable over IP networks using standard Ethernet switches, routers, and other components. Dante controller software manages data prioritization and signal routes."},{"title":"dB SPL","url":"https://sane-av.github.io/glossary/?search=dB%20SPL","type":"Glossary","snippet":"A measure of sound pressure level with reference to 0dB SPL (a sound pressure of 20 micropascal [µPa]).","tags":["Acoustics"],"text":"A measure of sound pressure level with reference to 0dB SPL (a sound pressure of 20 micropascal [µPa])."},{"title":"dBu","url":"https://sane-av.github.io/glossary/dbu/","type":"Glossary","snippet":"","tags":["Audio"],"text":"**dBu** is a decibel unit for measuring audio signal voltage, referenced to **0.775 V RMS**.\n\nThe reference voltage (0.775 V) is derived from the voltage required to dissipate 1 milliwatt\nof power across a 600 Ω resistive load - a legacy of telephone engineering. Today, the 600 Ω\nload is rarely used in audio equipment design, but the voltage reference (0 dBu = 0.775 V RMS)\nhas been retained as the professional audio standard.\n\n## Conversion\n\n| Relationship | Formula |\n|---|---|\n| dBu from voltage | `dBu = 20 × log₁₀(V / 0.775)` |\n| Voltage from dBu | `V = 0.775 × 10^(dBu/20)` |\n| dBu to dBV | `dBV = dBu − 2.218` |\n\n## Common Reference Points\n\n| Level | dBu | Voltage | Use |\n|-------|-----|---------|-----|\n| +4 dBu | +4 | 1.228 V RMS | Pro audio nominal |\n| 0 dBu | 0 | 0.775 V RMS | Reference voltage |\n| −10 dBu | −10 | 0.245 V RMS | Consumer nominal |\n\n## In Practice\n\nThe professional AV industry uses **+4 dBu** as the nominal operating level for line-level\nsignals (see [SANE-001](/standards/SANE-001-audio-levels)). Headroom of at least 20 dB above\nnominal is standard, placing the clip point at a minimum of +24 dBu.\n\n## Do Not Confuse With\n\n- **dBV**: Referenced to 1.0 V RMS, used in consumer equipment (−10 dBV is consumer nominal)\n- **dBFS**: Referenced to digital full scale, used in DAWs and digital audio equipment\n- **dBSPL**: Acoustic sound pressure level - an entirely different physical quantity"},{"title":"decay time","url":"https://sane-av.github.io/glossary/?search=decay%20time","type":"Glossary","snippet":"The time taken for an effect to diminish.","tags":["Acoustics"],"text":"The time taken for an effect to diminish."},{"title":"decibel","url":"https://sane-av.github.io/glossary/?search=decibel","type":"Glossary","snippet":"A base-10 logarithmic representation of the ratio between two numbers. This ratio is used for quantifying differences in voltage, distance, sound pressure, and power.","tags":["Acoustics","Electrical"],"text":"A base-10 logarithmic representation of the ratio between two numbers. This ratio is used for quantifying differences in voltage, distance, sound pressure, and power."},{"title":"decryption","url":"https://sane-av.github.io/glossary/?search=decryption","type":"Glossary","snippet":"The process of translating encrypted communications or data into its original form.","tags":["Signal Processing","Security"],"text":"The process of translating encrypted communications or data into its original form."},{"title":"DECT","url":"https://sane-av.github.io/glossary/?search=DECT","type":"Glossary","snippet":"Digital enhanced cordless telecommunications (DECT). A wireless communications protocol widely used for cordless telephone systems and some other portable devices.","tags":["Networking"],"text":"Digital enhanced cordless telecommunications (DECT). A wireless communications protocol widely used for cordless telephone systems and some other portable devices."},{"title":"delay","url":"https://sane-av.github.io/glossary/?search=delay","type":"Glossary","snippet":"A signal-processing device or circuit used to delay the delivery of a signal.","tags":["Electrical"],"text":"A signal-processing device or circuit used to delay the delivery of a signal."},{"title":"demodulator","url":"https://sane-av.github.io/glossary/?search=demodulator","type":"Glossary","snippet":"A device or process that extracts the information from a modulated signal.","tags":["General"],"text":"A device or process that extracts the information from a modulated signal."},{"title":"depth of field","url":"https://sane-av.github.io/glossary/?search=depth%20of%20field","type":"Glossary","snippet":"The area in front of a lens that is in focus. The distance from the closest focused item to the focused item farthest away.","tags":["Video"],"text":"The area in front of a lens that is in focus. The distance from the closest focused item to the focused item farthest away."},{"title":"detail drawing","url":"https://sane-av.github.io/glossary/?search=detail%20drawing","type":"Glossary","snippet":"A detail drawing which shows small details at a larger scale than the main drawing.","tags":["Project Management"],"text":"A detail drawing which shows small details at a larger scale than the main drawing."},{"title":"dielectric constant (relative permittivity)","url":"https://sane-av.github.io/glossary/?search=dielectric%20constant%20(relative%20permittivity)","type":"Glossary","snippet":"The ratio of the permittivity of a material compared to the permittivity of a vacuum. A measure of the dielectric strength of a material.","tags":["Electrical"],"text":"The ratio of the permittivity of a material compared to the permittivity of a vacuum. A measure of the dielectric strength of a material."},{"title":"dielectric strength","url":"https://sane-av.github.io/glossary/?search=dielectric%20strength","type":"Glossary","snippet":"The ability of a material to act as an insulator: how much potential difference it can withstand before breaking down and becoming a conductor.","tags":["Electrical"],"text":"The ability of a material to act as an insulator: how much potential difference it can withstand before breaking down and becoming a conductor."},{"title":"differential mode","url":"https://sane-av.github.io/glossary/?search=differential%20mode","type":"Glossary","snippet":"A signaling mode where two wires carry the same signal but one is in reverse polarity.","tags":["Signal Processing"],"text":"A signaling mode where two wires carry the same signal but one is in reverse polarity."},{"title":"differentiated service","url":"https://sane-av.github.io/glossary/?search=differentiated%20service","type":"Glossary","snippet":"A network quality-of-service (QoS) strategy wherein data from specific applications or protocols is assigned a class of service. Flows assigned a high priority are given preferential treatment at the router, but delivery is not guaranteed.","tags":["Networking"],"text":"A network quality-of-service (QoS) strategy wherein data from specific applications or protocols is assigned a class of service. Flows assigned a high priority are given preferential treatment at the router, but delivery is not guaranteed."},{"title":"diffusion","url":"https://sane-av.github.io/glossary/?search=diffusion","type":"Glossary","snippet":"The scattering or random reflection or transmission of a wave from a surface.","tags":["General"],"text":"The scattering or random reflection or transmission of a wave from a surface."},{"title":"digital media player","url":"https://sane-av.github.io/glossary/?search=digital%20media%20player","type":"Glossary","snippet":"Device or software application that replays recorded or streamed audio and video content.","tags":["Audio","Video","Systems & Control"],"text":"Device or software application that replays recorded or streamed audio and video content."},{"title":"digital signage","url":"https://sane-av.github.io/glossary/?search=digital%20signage","type":"Glossary","snippet":"Digital video displays used for signage. Sometimes referred to as dynamic signage to differentiate it from conventional static signage.","tags":["Video"],"text":"Digital video displays used for signage. Sometimes referred to as dynamic signage to differentiate it from conventional static signage."},{"title":"digital signage media player","url":"https://sane-av.github.io/glossary/?search=digital%20signage%20media%20player","type":"Glossary","snippet":"A specialized media player used to store and forward or play back digital signage content.","tags":["Video"],"text":"A specialized media player used to store and forward or play back digital signage content."},{"title":"digital signage template","url":"https://sane-av.github.io/glossary/?search=digital%20signage%20template","type":"Glossary","snippet":"Customizable layout and content templates used for the content of digital signage. Used to simplify the design and maintenance of standardized content.","tags":["Video"],"text":"Customizable layout and content templates used for the content of digital signage. Used to simplify the design and maintenance of standardized content."},{"title":"DSP (digital signal processor)","url":"https://sane-av.github.io/glossary/?search=digital%20signal%20processor","type":"Glossary","snippet":"A digital device designed to process signal streams such as audio, video, and RF data.","tags":["Audio","Video","Signal Processing"],"text":"A digital device designed to process signal streams such as audio, video, and RF data."},{"title":"digital-to-analog converter","url":"https://sane-av.github.io/glossary/?search=digital-to-analog%20converter","type":"Glossary","snippet":"A device that converts a digital signal into an analog form.","tags":["Signal Processing"],"text":"A device that converts a digital signal into an analog form."},{"title":"direct coupled","url":"https://sane-av.github.io/glossary/?search=direct%20coupled","type":"Glossary","snippet":"A loudspeaker signal distribution system in which the amplifier is connected directly to the loudspeaker(s).","tags":["Audio"],"text":"A loudspeaker signal distribution system in which the amplifier is connected directly to the loudspeaker(s)."},{"title":"DC (direct current)","url":"https://sane-av.github.io/glossary/?search=direct%20current","type":"Glossary","snippet":"Electric current that does not reverse direction, unlike alternating current (AC). DC may vary in amplitude but not direction.","tags":["Electrical"],"text":"Electric current that does not reverse direction, unlike alternating current (AC). DC may vary in amplitude but not direction."},{"title":"direct sound","url":"https://sane-av.github.io/glossary/?search=direct%20sound","type":"Glossary","snippet":"Also known as near-field. Sound that is received directly from the source and not colored by the acoustics of its surroundings.","tags":["Acoustics"],"text":"Also known as near-field. Sound that is received directly from the source and not colored by the acoustics of its surroundings."},{"title":"direct view display","url":"https://sane-av.github.io/glossary/?search=direct%20view%20display","type":"Glossary","snippet":"A display such as an LCD, LED, OLED, vacuum fluorescent, or plasma screen where the viewer is looking directly at the image source, not at a projection screen.","tags":["Video"],"text":"A display such as an LCD, LED, OLED, vacuum fluorescent, or plasma screen where the viewer is looking directly at the image source, not at a projection screen."},{"title":"directivity","url":"https://sane-av.github.io/glossary/?search=directivity","type":"Glossary","snippet":"The coverage pattern of loudspeakers.","tags":["Audio"],"text":"The coverage pattern of loudspeakers."},{"title":"dispersion","url":"https://sane-av.github.io/glossary/?search=dispersion","type":"Glossary","snippet":"The separation of light into different frequencies/wavelengths, such as when a white light beam passes through a triangular prism. The different wavelengths of light refract at different angles, dispersing the light into its individual wavelengths.","tags":["Lighting"],"text":"The separation of light into different frequencies/wavelengths, such as when a white light beam passes through a triangular prism. The different wavelengths of light refract at different angles, dispersing the light into its individual wavelengths."},{"title":"DDC (Display Data Channel)","url":"https://sane-av.github.io/glossary/?search=Display%20Data%20Channel","type":"Glossary","snippet":"A data channel used between video sources and video displays to carry information about display capabilities and video formats. The channel used for exchanging EDID and HDCP data.","tags":["Video","Security"],"text":"A data channel used between video sources and video displays to carry information about display capabilities and video formats. The channel used for exchanging EDID and HDCP data."},{"title":"DisplayID","url":"https://sane-av.github.io/glossary/?search=DisplayID","type":"Glossary","snippet":"A standard developed by VESA outlining how video display data is structured to describe the display’s performance and capabilities when communicating with other devices. By structuring data in a flexible, modular way, DisplayID enables devices to identify new display resolutions, refresh rates, audio standards, and other formats as they become available. For example, the standard can support a single image segmented across tiled displays using multiple video processors.","tags":["Audio","Video","Standards"],"text":"A standard developed by VESA outlining how video display data is structured to describe the display’s performance and capabilities when communicating with other devices. By structuring data in a flexible, modular way, DisplayID enables devices to identify new display resolutions, refresh rates, audio standards, and other formats as they become available. For example, the standard can support a single image segmented across tiled displays using multiple video processors."},{"title":"DisplayPort","url":"https://sane-av.github.io/glossary/?search=DisplayPort","type":"Glossary","snippet":"A VESA-developed, high-speed digital data transport protocol used to connect a video source to display devices. It can also carry audio, USB, and other data.","tags":["Audio","Video","Signal Processing","Standards"],"text":"A VESA-developed, high-speed digital data transport protocol used to connect a video source to display devices. It can also carry audio, USB, and other data."},{"title":"distributed sound system","url":"https://sane-av.github.io/glossary/?search=distributed%20sound%20system","type":"Glossary","snippet":"A sound system using multiple distributed loudspeakers to provide sound coverage across an area at a constant sound pressure level.","tags":["Acoustics","Audio"],"text":"A sound system using multiple distributed loudspeakers to provide sound coverage across an area at a constant sound pressure level."},{"title":"DA (distribution amplifier)","url":"https://sane-av.github.io/glossary/?search=distribution%20amplifier","type":"Glossary","snippet":"An active device used to split one input signal into multiple isolated output signals at a constant amplitude.","tags":["Audio","Signal Processing"],"text":"An active device used to split one input signal into multiple isolated output signals at a constant amplitude."},{"title":"diversity receiver","url":"https://sane-av.github.io/glossary/?search=diversity%20receiver","type":"Glossary","snippet":"An RF receiver that uses multiple antennas to receive a single RF transmission. The receiver calculates phase differences between the received signals to dynamically shift between antennas to avoid multipath signal cancellation.","tags":["Electrical"],"text":"An RF receiver that uses multiple antennas to receive a single RF transmission. The receiver calculates phase differences between the received signals to dynamically shift between antennas to avoid multipath signal cancellation."},{"title":"DLP","url":"https://sane-av.github.io/glossary/?search=DLP","type":"Glossary","snippet":"Digital Light Processing. A projection technology based on the MEMS digital micromirror device (DMD) chip family. It uses a matrix of thousands of movable microscopic mirrors on a chip to display images on a screen.","tags":["Video"],"text":"Digital Light Processing. A projection technology based on the MEMS digital micromirror device (DMD) chip family. It uses a matrix of thousands of movable microscopic mirrors on a chip to display images on a screen."},{"title":"DNS (Domain Name System)","url":"https://sane-av.github.io/glossary/?search=Domain%20Name%20System","type":"Glossary","snippet":"A hierarchical, distributed database that maps names to data such as IP addresses, name server addresses, and mail exchange addresses.","tags":["Networking"],"text":"A hierarchical, distributed database that maps names to data such as IP addresses, name server addresses, and mail exchange addresses."},{"title":"dome","url":"https://sane-av.github.io/glossary/?search=dome","type":"Glossary","snippet":"A type of loudspeaker driver construction. Fabric, thin metallic, or woven materials are used to create a dome-shaped diaphragm. The voice coil is attached to the edge of the dome-shaped diaphragm.","tags":["Audio"],"text":"A type of loudspeaker driver construction. Fabric, thin metallic, or woven materials are used to create a dome-shaped diaphragm. The voice coil is attached to the edge of the dome-shaped diaphragm."},{"title":"dotted-decimal/dotted-quad notation","url":"https://sane-av.github.io/glossary/?search=dotted-decimal%2Fdotted-quad%20notation","type":"Glossary","snippet":"A format commonly used for expressing 32-bit IPv4 addresses using four decimal numbers in the range 0 to 255, separated by decimal points (dots) (e.g., 192.168.12.254).","tags":["Networking"],"text":"A format commonly used for expressing 32-bit IPv4 addresses using four decimal numbers in the range 0 to 255, separated by decimal points (dots) (e.g., 192.168.12.254)."},{"title":"driver","url":"https://sane-av.github.io/glossary/?search=driver","type":"Glossary","snippet":"1. In audio, an individual loudspeaker unit. 2. In electronics, a piece of software or firmware that takes a high-level command set and implements the commands in a specific format for the actual hardware or software present in the system.","tags":["Audio"],"text":"1. In audio, an individual loudspeaker unit. 2. In electronics, a piece of software or firmware that takes a high-level command set and implements the commands in a specific format for the actual hardware or software present in the system."},{"title":"dual channel","url":"https://sane-av.github.io/glossary/?search=dual%20channel","type":"Glossary","snippet":"In test equipment, refers to a test device with two independent input channels.","tags":["Audio"],"text":"In test equipment, refers to a test device with two independent input channels."},{"title":"DVD","url":"https://sane-av.github.io/glossary/?search=DVD","type":"Glossary","snippet":"Digital Video Disc or Digital Versatile Disc. An optical storage medium for digital data or video. Widely used for video content distribution from the late 1990s to approximately 2015.","tags":["Video","Cabling"],"text":"Digital Video Disc or Digital Versatile Disc. An optical storage medium for digital data or video. Widely used for video content distribution from the late 1990s to approximately 2015."},{"title":"DVI","url":"https://sane-av.github.io/glossary/?search=DVI","type":"Glossary","snippet":"Digital Visual Interface. A digital interface to connect an uncompressed video source to a display device. DVI has largely been replaced by HDMI, DisplayPort, and other formats.","tags":["Video"],"text":"Digital Visual Interface. A digital interface to connect an uncompressed video source to a display device. DVI has largely been replaced by HDMI, DisplayPort, and other formats."},{"title":"DHCP (Dynamic Host Configuration Protocol)","url":"https://sane-av.github.io/glossary/?search=Dynamic%20Host%20Configuration%20Protocol","type":"Glossary","snippet":"An IP address management process that automates the assignment of IP addresses and networking parameters to devices on an IP network.","tags":["Networking"],"text":"An IP address management process that automates the assignment of IP addresses and networking parameters to devices on an IP network."},{"title":"dynamic microphone","url":"https://sane-av.github.io/glossary/?search=dynamic%20microphone","type":"Glossary","snippet":"A microphone with a diaphragm attached to a moveable coil of wire located in a magnetic field. Sound pressure waves cause the diaphragm to move the coil in the magnetic field, inducing a small electric current in the coil.","tags":["Acoustics","Audio","Electrical","Cabling"],"text":"A microphone with a diaphragm attached to a moveable coil of wire located in a magnetic field. Sound pressure waves cause the diaphragm to move the coil in the magnetic field, inducing a small electric current in the coil."},{"title":"dynamic range","url":"https://sane-av.github.io/glossary/?search=dynamic%20range","type":"Glossary","snippet":"The difference between the highest and lowest levels of a signal. Usually expressed in decibels (dB).","tags":["Audio"],"text":"The difference between the highest and lowest levels of a signal. Usually expressed in decibels (dB)."},{"title":"early reflected sound","url":"https://sane-av.github.io/glossary/?search=early%20reflected%20sound","type":"Glossary","snippet":"The sound waves that arrive at the listener’s ear closely following (<30ms) the direct sound wave. These are the sound waves that are reflected off surfaces between the source and the listener.","tags":["General"],"text":"The sound waves that arrive at the listener’s ear closely following (<30ms) the direct sound wave. These are the sound waves that are reflected off surfaces between the source and the listener."},{"title":"earthing conductor","url":"https://sane-av.github.io/glossary/?search=earthing%20conductor","type":"Glossary","snippet":"A conductor used to connect equipment or the grounded circuit of a wiring system to a grounding/ earthing electrode (planet Earth).","tags":["Electrical","Cabling"],"text":"A conductor used to connect equipment or the grounded circuit of a wiring system to a grounding/ earthing electrode (planet Earth)."},{"title":"echo","url":"https://sane-av.github.io/glossary/?search=echo","type":"Glossary","snippet":"A reflected or duplicated version of a signal that arrives at the listener with sufficient delay and separation from the original signal to allow the delayed signal to be perceived distinctly and later in time from the original signal.","tags":["General"],"text":"A reflected or duplicated version of a signal that arrives at the listener with sufficient delay and separation from the original signal to allow the delayed signal to be perceived distinctly and later in time from the original signal."},{"title":"echo cancellation","url":"https://sane-av.github.io/glossary/?search=echo%20cancellation","type":"Glossary","snippet":"A means of eliminating echo from a signal path.","tags":["Acoustics"],"text":"A means of eliminating echo from a signal path."},{"title":"eggcrate","url":"https://sane-av.github.io/glossary/?search=eggcrate","type":"Glossary","snippet":"A light baffle with rectangular cells that direct, block, and diffuse light.","tags":["Lighting"],"text":"A light baffle with rectangular cells that direct, block, and diffuse light."},{"title":"electret microphone","url":"https://sane-av.github.io/glossary/?search=electret%20microphone","type":"Glossary","snippet":"A type of condenser microphone using a prepolarized material, called an electret, which is applied to the microphone’s diaphragm or backplate.","tags":["Audio"],"text":"A type of condenser microphone using a prepolarized material, called an electret, which is applied to the microphone’s diaphragm or backplate."},{"title":"electrical service","url":"https://sane-av.github.io/glossary/?search=electrical%20service","type":"Glossary","snippet":"The conductors and equipment for delivering energy from the electricity supply system to the wiring system of the site served.","tags":["Electrical","Cabling"],"text":"The conductors and equipment for delivering energy from the electricity supply system to the wiring system of the site served."},{"title":"EMI (electromagnetic interference)","url":"https://sane-av.github.io/glossary/?search=electromagnetic%20interference","type":"Glossary","snippet":"Interference signals produced by electromagnetic fields.","tags":["General"],"text":"Interference signals produced by electromagnetic fields."},{"title":"elevation drawing","url":"https://sane-av.github.io/glossary/?search=elevation%20drawing","type":"Glossary","snippet":"A side view of an object or surface taken in the vertical plane from outside the object or surface.","tags":["Project Management"],"text":"A side view of an object or surface taken in the vertical plane from outside the object or surface."},{"title":"emissive technology","url":"https://sane-av.github.io/glossary/?search=emissive%20technology","type":"Glossary","snippet":"Any display technology that emits light to create an image.","tags":["Video"],"text":"Any display technology that emits light to create an image."},{"title":"encoded","url":"https://sane-av.github.io/glossary/?search=encoded","type":"Glossary","snippet":"A signal that has been converted into another format.","tags":["Signal Processing"],"text":"A signal that has been converted into another format."},{"title":"encryption","url":"https://sane-av.github.io/glossary/?search=encryption","type":"Glossary","snippet":"The process of transforming communications or data into a form that cannot easily be understood by recipients who have not been granted access to it.","tags":["Signal Processing","Security"],"text":"The process of transforming communications or data into a form that cannot easily be understood by recipients who have not been granted access to it."},{"title":"EMP (energy management plan)","url":"https://sane-av.github.io/glossary/?search=energy%20management%20plan","type":"Glossary","snippet":"A document that details a systematic approach to implementing the most effective power consumption methods and procedures to achieve and maintain optimum energy usage.","tags":["Project Management"],"text":"A document that details a systematic approach to implementing the most effective power consumption methods and procedures to achieve and maintain optimum energy usage."},{"title":"equalizer","url":"https://sane-av.github.io/glossary/?search=equalizer","type":"Glossary","snippet":"Electronic equipment that modifies the frequency characteristics of a signal.","tags":["Audio"],"text":"Electronic equipment that modifies the frequency characteristics of a signal."},{"title":"equipment grounding","url":"https://sane-av.github.io/glossary/?search=equipment%20grounding","type":"Glossary","snippet":"The connection to ground (planet Earth) from the conductive, user-accessible parts of equipment.","tags":["Electrical"],"text":"The connection to ground (planet Earth) from the conductive, user-accessible parts of equipment."},{"title":"EGC (equipment grounding conductor)","url":"https://sane-av.github.io/glossary/?search=equipment%20grounding%20conductor","type":"Glossary","snippet":"North American term for the safety earth, the conductive path installed to connect normally noncurrent-carrying conductive parts of equipment to the grounding/earthing electrode (planet Earth).","tags":["Electrical"],"text":"North American term for the safety earth, the conductive path installed to connect normally noncurrent-carrying conductive parts of equipment to the grounding/earthing electrode (planet Earth)."},{"title":"equipment rack","url":"https://sane-av.github.io/glossary/?search=equipment%20rack","type":"Glossary","snippet":"An equipment housing unit that protects and organizes electronic equipment.","tags":["Project Management"],"text":"An equipment housing unit that protects and organizes electronic equipment."},{"title":"EAD (equivalent acoustic distance)","url":"https://sane-av.github.io/glossary/?search=equivalent%20acoustic%20distance","type":"Glossary","snippet":"The farthest distance one can go from the source without the need for sound amplification or reinforcement to maintain good speech intelligibility. The distance is dependent on the level of the presenter and the noise level in the room.","tags":["Acoustics"],"text":"The farthest distance one can go from the source without the need for sound amplification or reinforcement to maintain good speech intelligibility. The distance is dependent on the level of the presenter and the noise level in the room."},{"title":"ergonomics","url":"https://sane-av.github.io/glossary/?search=ergonomics","type":"Glossary","snippet":"Also known as human factors or human factors engineering. This is the scientific study of the way people interact with a system. It focuses on effectiveness, efficiency, reducing errors, increasing productivity, improving safety, reducing fatigue and stress, increasing comfort, increasing user acceptance, increasing job satisfaction, and improving quality of life.","tags":["Systems & Control"],"text":"Also known as human factors or human factors engineering. This is the scientific study of the way people interact with a system. It focuses on effectiveness, efficiency, reducing errors, increasing productivity, improving safety, reducing fatigue and stress, increasing comfort, increasing user acceptance, increasing job satisfaction, and improving quality of life."},{"title":"Ethernet","url":"https://sane-av.github.io/glossary/?search=Ethernet","type":"Glossary","snippet":"A set of network cabling, signaling, and network access protocol standards. Before the introduction of switch-based networks, Ethernet was based on carrier-sense multiple access technology with collision detection (CSMA/CD).","tags":["Networking"],"text":"A set of network cabling, signaling, and network access protocol standards. Before the introduction of switch-based networks, Ethernet was based on carrier-sense multiple access technology with collision detection (CSMA/CD)."},{"title":"EtherSound","url":"https://sane-av.github.io/glossary/?search=EtherSound","type":"Glossary","snippet":"A proprietary digital audio Data Link-layer (layer 2) protocol designed by Digigram. It uses standard 100Mbps or 1Gbps Ethernet cabling, switches, and other components. It requires a separate network with dedicated bandwidth. EtherSound signals are nonroutable.","tags":["Audio","Networking"],"text":"A proprietary digital audio Data Link-layer (layer 2) protocol designed by Digigram. It uses standard 100Mbps or 1Gbps Ethernet cabling, switches, and other components. It requires a separate network with dedicated bandwidth. EtherSound signals are nonroutable."},{"title":"expander","url":"https://sane-av.github.io/glossary/?search=expander","type":"Glossary","snippet":"An audio processor that increases the dynamic range of an audio signal. It comes in two types: a downward expander and as part of a compander.","tags":["Audio"],"text":"An audio processor that increases the dynamic range of an audio signal. It comes in two types: a downward expander and as part of a compander."},{"title":"exploit","url":"https://sane-av.github.io/glossary/?search=exploit","type":"Glossary","snippet":"An attack technique intended to take advantage of a vulnerability to breach the security of a network or gain information.","tags":["Audio","Security"],"text":"An attack technique intended to take advantage of a vulnerability to breach the security of a network or gain information."},{"title":"EDID (extended display identification data)","url":"https://sane-av.github.io/glossary/?search=extended%20display%20identification%20data","type":"Glossary","snippet":"A data structure within a video sink device that is used to describe the sink’s characteristics to a video source. The characteristics described include the sink’s native resolution, color space information, and audio type (mono or stereo).","tags":["Audio","Video"],"text":"A data structure within a video sink device that is used to describe the sink’s characteristics to a video source. The characteristics described include the sink’s native resolution, color space information, and audio type (mono or stereo)."},{"title":"external configuration","url":"https://sane-av.github.io/glossary/?search=external%20configuration","type":"Glossary","snippet":"Refers to the ability of one device to configure other devices and subsystems.","tags":["Systems & Control"],"text":"Refers to the ability of one device to configure other devices and subsystems."},{"title":"far field","url":"https://sane-av.github.io/glossary/?search=far%20field","type":"Glossary","snippet":"The sound field distant enough from the sound source that the SPL decreases by 6dB for each doubling of the distance from the source.","tags":["Acoustics"],"text":"The sound field distant enough from the sound source that the SPL decreases by 6dB for each doubling of the distance from the source."},{"title":"Faraday cage","url":"https://sane-av.github.io/glossary/?search=Faraday%20cage","type":"Glossary","snippet":"A conductive solid or mesh enclosure used to block electromagnetic fields. Also known as a Faraday shield. Named after its inventor Michael Faraday.","tags":["Cabling"],"text":"A conductive solid or mesh enclosure used to block electromagnetic fields. Also known as a Faraday shield. Named after its inventor Michael Faraday."},{"title":"farthest viewer","url":"https://sane-av.github.io/glossary/?search=farthest%20viewer","type":"Glossary","snippet":"The viewer positioned at the farthest distance from the screen as defined by the viewing area.","tags":["Video"],"text":"The viewer positioned at the farthest distance from the screen as defined by the viewing area."},{"title":"feedback","url":"https://sane-av.github.io/glossary/?search=feedback","type":"Glossary","snippet":"1. In audio, unwanted noise caused by the loop of an audio system’s output back to its input. 2. In a control system, data supplied to give an indication of system performance or status.","tags":["Audio","Systems & Control"],"text":"1. In audio, unwanted noise caused by the loop of an audio system’s output back to its input. 2. In a control system, data supplied to give an indication of system performance or status."},{"title":"FSM (feedback stability margin)","url":"https://sane-av.github.io/glossary/?search=feedback%20stability%20margin","type":"Glossary","snippet":"The extra margin added (usually 6dB) into the needed acoustic gain (NAG) formula that represents extra gain that a sound system may have available before the onset of feedback.","tags":["Acoustics","Audio"],"text":"The extra margin added (usually 6dB) into the needed acoustic gain (NAG) formula that represents extra gain that a sound system may have available before the onset of feedback."},{"title":"fiber-optic","url":"https://sane-av.github.io/glossary/?search=fiber-optic","type":"Glossary","snippet":"A technology that uses total internal reflection of light along a transparent fiber to transmit information.","tags":["Cabling"],"text":"A technology that uses total internal reflection of light along a transparent fiber to transmit information."},{"title":"field","url":"https://sane-av.github.io/glossary/?search=field","type":"Glossary","snippet":"In interlaced video, one-half of a video frame containing every other line of information. Each interlaced video frame contains two fields.","tags":["Video"],"text":"In interlaced video, one-half of a video frame containing every other line of information. Each interlaced video frame contains two fields."},{"title":"filter","url":"https://sane-av.github.io/glossary/?search=filter","type":"Glossary","snippet":"A device or process that blocks or passes certain elements of a signal.","tags":["Signal Processing"],"text":"A device or process that blocks or passes certain elements of a signal."},{"title":"firewall","url":"https://sane-av.github.io/glossary/?search=firewall","type":"Glossary","snippet":"Any technology, hardware, or software that regulates the traffic permitted to enter or exit a network. Firewalls control access across network boundaries.","tags":["Networking","Security"],"text":"Any technology, hardware, or software that regulates the traffic permitted to enter or exit a network. Firewalls control access across network boundaries."},{"title":"firewall traversal","url":"https://sane-av.github.io/glossary/?search=firewall%20traversal","type":"Glossary","snippet":"Any firewall or Application-layer gateway (ALG) is expected to provide mechanisms that allows traffic to traverse through the firewall/ALG to reach an intended destination. Firewall traversal is provided in multiple ways, including NAT traversal, IPSec tunnels, IP ACLs (access control lists), or port-based ACLs.","tags":["Networking","Security"],"text":"Any firewall or Application-layer gateway (ALG) is expected to provide mechanisms that allows traffic to traverse through the firewall/ALG to reach an intended destination. Firewall traversal is provided in multiple ways, including NAT traversal, IPSec tunnels, IP ACLs (access control lists), or port-based ACLs."},{"title":"firmware","url":"https://sane-av.github.io/glossary/?search=firmware","type":"Glossary","snippet":"A type of software that is stored in nonvolatile memory in a piece of hardware.","tags":["General"],"text":"A type of software that is stored in nonvolatile memory in a piece of hardware."},{"title":"fixture","url":"https://sane-av.github.io/glossary/?search=fixture","type":"Glossary","snippet":"A luminaire that is mounted or fixed in place.","tags":["Cabling","Lighting"],"text":"A luminaire that is mounted or fixed in place."},{"title":"flex life","url":"https://sane-av.github.io/glossary/?search=flex%20life","type":"Glossary","snippet":"The number of times a cable can be bent before it breaks. A wire with more strands or twists per meter will have a greater flex life than one with a lower number of strands or fewer twists per meter.","tags":["Cabling"],"text":"The number of times a cable can be bent before it breaks. A wire with more strands or twists per meter will have a greater flex life than one with a lower number of strands or fewer twists per meter."},{"title":"focal length","url":"https://sane-av.github.io/glossary/?search=focal%20length","type":"Glossary","snippet":"The distance between the center of a lens and the point where the image comes into focus. The shorter the focal length, the wider the angle of the image will be.","tags":["Video"],"text":"The distance between the center of a lens and the point where the image comes into focus. The shorter the focal length, the wider the angle of the image will be."},{"title":"foot-candle","url":"https://sane-av.github.io/glossary/?search=foot-candle","type":"Glossary","snippet":"The U.S. customary unit of illuminance. The incident light measured when 1 lumen of light is spread over an area of 1 square foot. Its symbol is fc. 1 foot-candle = 10.76 lux.","tags":["Video","Lighting","Security"],"text":"The U.S. customary unit of illuminance. The incident light measured when 1 lumen of light is spread over an area of 1 square foot. Its symbol is fc. 1 foot-candle = 10.76 lux."},{"title":"footlambert","url":"https://sane-av.github.io/glossary/?search=footlambert","type":"Glossary","snippet":"The footlambert is the U.S. customary unit for luminance. It is equal to 1/π candela per square foot. Its symbol is fl. 1 footlambert = 3.43 candela per square meter.","tags":["Video","Lighting"],"text":"The footlambert is the U.S. customary unit for luminance. It is equal to 1/π candela per square foot. Its symbol is fl. 1 footlambert = 3.43 candela per square meter."},{"title":"frame rate","url":"https://sane-av.github.io/glossary/?search=frame%20rate","type":"Glossary","snippet":"The number of frames per second sent from a source.","tags":["Video"],"text":"The number of frames per second sent from a source."},{"title":"frequency","url":"https://sane-av.github.io/glossary/?search=frequency","type":"Glossary","snippet":"The number of complete cycles in a specified period of time. It is measured in hertz (Hz). 1Hz = 1 cycle per second.","tags":["General"],"text":"The number of complete cycles in a specified period of time. It is measured in hertz (Hz). 1Hz = 1 cycle per second."},{"title":"frequency domain","url":"https://sane-av.github.io/glossary/?search=frequency%20domain","type":"Glossary","snippet":"A signal viewed as frequency versus amplitude is in the frequency domain. This allows you to view the amount of energy present at different frequencies.","tags":["General"],"text":"A signal viewed as frequency versus amplitude is in the frequency domain. This allows you to view the amount of energy present at different frequencies."},{"title":"frequency response","url":"https://sane-av.github.io/glossary/?search=frequency%20response","type":"Glossary","snippet":"The amplitude response versus frequency for a given device.","tags":["General"],"text":"The amplitude response versus frequency for a given device."},{"title":"Fresnel lens","url":"https://sane-av.github.io/glossary/?search=Fresnel%20lens","type":"Glossary","snippet":"A flat lens in which the curvature of a normal lens surface has been collapsed in such a way that concentric circles are impressed on the lens surface. A Fresnel lens is often used for the condenser lens in overhead projectors, in rear-screen projection systems, and in Fresnel spotlights.","tags":["Video"],"text":"A flat lens in which the curvature of a normal lens surface has been collapsed in such a way that concentric circles are impressed on the lens surface. A Fresnel lens is often used for the condenser lens in overhead projectors, in rear-screen projection systems, and in Fresnel spotlights."},{"title":"front-screen projection","url":"https://sane-av.github.io/glossary/?search=front-screen%20projection","type":"Glossary","snippet":"An image projection system where the image is projected from a source on the viewer’s side of the screen.","tags":["Video"],"text":"An image projection system where the image is projected from a source on the viewer’s side of the screen."},{"title":"full HD","url":"https://sane-av.github.io/glossary/?search=full%20HD","type":"Glossary","snippet":"A high-definition video mode with a resolution of 1920×1080 pixels.","tags":["Video"],"text":"A high-definition video mode with a resolution of 1920×1080 pixels."},{"title":"full-duplex communication","url":"https://sane-av.github.io/glossary/?search=full-duplex%20communication","type":"Glossary","snippet":"A form of bi-directional data transmission in which messages may simultaneously travel in both directions.","tags":["Networking"],"text":"A form of bi-directional data transmission in which messages may simultaneously travel in both directions."},{"title":"fundamental frequency","url":"https://sane-av.github.io/glossary/?search=fundamental%20frequency","type":"Glossary","snippet":"Known as pure tone, the lowest frequency in a harmonic series.","tags":["General"],"text":"Known as pure tone, the lowest frequency in a harmonic series."},{"title":"gain","url":"https://sane-av.github.io/glossary/?search=gain","type":"Glossary","snippet":"The change in the amplitude of a signal.","tags":["Audio"],"text":"The change in the amplitude of a signal."},{"title":"gain control","url":"https://sane-av.github.io/glossary/?search=gain%20control","type":"Glossary","snippet":"A gain control is an electronic adjustment through which the amplitude of a signal can be increased or decreased.","tags":["Audio"],"text":"A gain control is an electronic adjustment through which the amplitude of a signal can be increased or decreased."},{"title":"Gain Structure","url":"https://sane-av.github.io/glossary/gain-structure/","type":"Glossary","snippet":"","tags":["Audio"],"text":"**Gain structure** refers to the deliberate setting of signal levels at each stage of an\naudio signal chain to maintain an optimal signal-to-noise ratio while preserving sufficient\nheadroom to prevent clipping.\n\nA properly gain-structured system keeps the signal well above the noise floor at every stage\nand well below the clip point, so that the dynamic range of the system is fully utilized\nwithout distortion.\n\n## The Problem Gain Structure Solves\n\nEvery electronic component introduces noise. If a signal enters a stage at too low a level,\nthe component's internal noise is amplified along with the signal in subsequent stages,\ndegrading the signal-to-noise ratio. If a signal is too high, it clips, introducing severe\nharmonic distortion.\n\nGain structure ensures neither happens.\n\n## Basic Principle\n\n1. **Set the source** to output its nominal level (e.g., +4 dBu for pro line level)\n2. **Set each stage** so nominal input produces nominal output - unity gain through the chain\n3. **Use output attenuation** (volume controls, faders) to reduce level when needed,\n   rather than reducing input gain\n4. **Verify headroom** at every stage: clip point should be ≥ 20 dB above nominal\n\n## Common Mistakes\n\n- **Cranking input gain to compensate for a quiet source** - amplifies noise from the source\n- **Running the main fader at minimum with channel faders at maximum** - inverts the gain\n  structure and pushes noise into downstream stages\n- **Not accounting for summing** - mixing multiple channels together can increase the\n  composite signal level, requiring additional headroom planning\n\n## Reference\n\nSee [SANE-001](/standards/SANE-001-audio-levels) for normative signal level specifications."},{"title":"gain-sharing automatic mixers","url":"https://sane-av.github.io/glossary/?search=gain-sharing%20automatic%20mixers","type":"Glossary","snippet":"A gain-sharing automatic mixer is an audio mixer that automatically increases the gain for microphone channels that are in use and attenuates the microphone channels that are not in use.","tags":["Audio","Signal Processing"],"text":"A gain-sharing automatic mixer is an audio mixer that automatically increases the gain for microphone channels that are in use and attenuates the microphone channels that are not in use."},{"title":"gate","url":"https://sane-av.github.io/glossary/?search=gate","type":"Glossary","snippet":"An audio processor that allows signals to pass only above a certain setting or threshold.","tags":["Audio"],"text":"An audio processor that allows signals to pass only above a certain setting or threshold."},{"title":"gated automatic mixer","url":"https://sane-av.github.io/glossary/?search=gated%20automatic%20mixer","type":"Glossary","snippet":"An audio mixer that turns microphone channels either “on” or “off” automatically, based on the amplitude of their signal.","tags":["Audio"],"text":"An audio mixer that turns microphone channels either “on” or “off” automatically, based on the amplitude of their signal."},{"title":"gateway","url":"https://sane-av.github.io/glossary/?search=gateway","type":"Glossary","snippet":"A router device that connects a local network to an external network. All outgoing network traffic must travel through it. A gateway will pass incoming traffic to the routers below. The routers below look to the gateway to resolve DNS addresses not found on the local network.","tags":["Networking"],"text":"A router device that connects a local network to an external network. All outgoing network traffic must travel through it. A gateway will pass incoming traffic to the routers below. The routers below look to the gateway to resolve DNS addresses not found on the local network."},{"title":"gauge","url":"https://sane-av.github.io/glossary/?search=gauge","type":"Glossary","snippet":"The thickness or diameter of a wire or plate.","tags":["Cabling"],"text":"The thickness or diameter of a wire or plate."},{"title":"genlock","url":"https://sane-av.github.io/glossary/?search=genlock","type":"Glossary","snippet":"To lock the synchronization signals of multiple devices to a single synchronization source.","tags":["Video"],"text":"To lock the synchronization signals of multiple devices to a single synchronization source."},{"title":"graphic equalizer","url":"https://sane-av.github.io/glossary/?search=graphic%20equalizer","type":"Glossary","snippet":"An audio equalizer with an interface that has a graph comparing amplitude on the vertical axis with frequency on the horizontal axis.","tags":["Audio","Signal Processing"],"text":"An audio equalizer with an interface that has a graph comparing amplitude on the vertical axis with frequency on the horizontal axis."},{"title":"GUI (graphical user interface)","url":"https://sane-av.github.io/glossary/?search=graphical%20user%20interface","type":"Glossary","snippet":"Often pronounced “gooey,” provides a graphical (image-based) interface for a user to view a system’s elements and functions.","tags":["Video","Systems & Control"],"text":"Often pronounced “gooey,” provides a graphical (image-based) interface for a user to view a system’s elements and functions."},{"title":"graphics adapter","url":"https://sane-av.github.io/glossary/?search=graphics%20adapter","type":"Glossary","snippet":"Commonly referred to as a video card, a device that generates and outputs video signals from a computer.","tags":["Video"],"text":"Commonly referred to as a video card, a device that generates and outputs video signals from a computer."},{"title":"GPU (graphics processing unit)","url":"https://sane-av.github.io/glossary/?search=graphics%20processing%20unit","type":"Glossary","snippet":"A specialized circuit designed for processing display functions. The processor is optimized to render and manipulate images in a video frame buffer.","tags":["Video","Electrical"],"text":"A specialized circuit designed for processing display functions. The processor is optimized to render and manipulate images in a video frame buffer."},{"title":"grayscale","url":"https://sane-av.github.io/glossary/?search=grayscale","type":"Glossary","snippet":"The luminance (brightness and darkness) of a color. It is sometimes called value. It is one of the three attributes of color; the other two are hue and chroma.","tags":["Video"],"text":"The luminance (brightness and darkness) of a color. It is sometimes called value. It is one of the three attributes of color; the other two are hue and chroma."},{"title":"grayscale test pattern","url":"https://sane-av.github.io/glossary/?search=grayscale%20test%20pattern","type":"Glossary","snippet":"A test pattern that displays a range of known gray values between black and white.","tags":["Video"],"text":"A test pattern that displays a range of known gray values between black and white."},{"title":"ground","url":"https://sane-av.github.io/glossary/?search=ground","type":"Glossary","snippet":"1. The earth. 2. In the context of an electrical circuit, the earth or some conductive body that extends the ground (earth) connection. 3. In the context of electronics, the 0V (zero volt) circuit reference point. This electronic circuit reference point may or may not have a connection to the earth.","tags":["Electrical"],"text":"1. The earth. 2. In the context of an electrical circuit, the earth or some conductive body that extends the ground (earth) connection. 3. In the context of electronics, the 0V (zero volt) circuit reference point. This electronic circuit reference point may or may not have a connection to the earth."},{"title":"ground fault","url":"https://sane-av.github.io/glossary/?search=ground%20fault","type":"Glossary","snippet":"An unintentional electrical connection between any ungrounded conductor of the electrical system and any noncurrent-carrying metal object.","tags":["Electrical"],"text":"An unintentional electrical connection between any ungrounded conductor of the electrical system and any noncurrent-carrying metal object."},{"title":"ground loop","url":"https://sane-av.github.io/glossary/?search=ground%20loop","type":"Glossary","snippet":"An electrically conductive loop that has two or more ground reference connections. The loop can be detrimental when the reference connections are at different potentials, which causes current flow within the loop.","tags":["Electrical"],"text":"An electrically conductive loop that has two or more ground reference connections. The loop can be detrimental when the reference connections are at different potentials, which causes current flow within the loop."},{"title":"ground plane","url":"https://sane-av.github.io/glossary/?search=ground%20plane","type":"Glossary","snippet":"A continuous conductive area. The fundamental property of a ground plane is that every point on its surface is at the same potential (low impedance) at all frequencies of concern.","tags":["Electrical"],"text":"A continuous conductive area. The fundamental property of a ground plane is that every point on its surface is at the same potential (low impedance) at all frequencies of concern."},{"title":"ground potential","url":"https://sane-av.github.io/glossary/?search=ground%20potential","type":"Glossary","snippet":"A point in a circuit that is at the same potential as the earth/ground.","tags":["Electrical"],"text":"A point in a circuit that is at the same potential as the earth/ground."},{"title":"ground reference","url":"https://sane-av.github.io/glossary/?search=ground%20reference","type":"Glossary","snippet":"The 0V (zero volt) reference point for a circuit.","tags":["Electrical"],"text":"The 0V (zero volt) reference point for a circuit."},{"title":"GFCI (ground-fault circuit interrupter)","url":"https://sane-av.github.io/glossary/?search=ground-fault%20circuit%20interrupter","type":"Glossary","snippet":"A safety device that de-energizes a circuit within an established period of time when a current to ground exceeds a specified level. Triggered by an imbalance between the supply and return currents. Similar in function to an earth leakage circuit breaker (ELCB), a residual current device (RCD), or a core balance relay (CBR).","tags":["Electrical"],"text":"A safety device that de-energizes a circuit within an established period of time when a current to ground exceeds a specified level. Triggered by an imbalance between the supply and return currents. Similar in function to an earth leakage circuit breaker (ELCB), a residual current device (RCD), or a core balance relay (CBR)."},{"title":"ground-fault current path","url":"https://sane-av.github.io/glossary/?search=ground-fault%20current%20path","type":"Glossary","snippet":"An electrically conductive path from the point of a ground fault on a wiring system through normally noncurrent-carrying conductors, equipment, or earth to the electrical supply source.","tags":["Electrical","Cabling"],"text":"An electrically conductive path from the point of a ground fault on a wiring system through normally noncurrent-carrying conductors, equipment, or earth to the electrical supply source."},{"title":"grounded conductor","url":"https://sane-av.github.io/glossary/?search=grounded%20conductor","type":"Glossary","snippet":"A system or circuit conductor that is connected to the earth/ground.","tags":["Electrical"],"text":"A system or circuit conductor that is connected to the earth/ground."},{"title":"grounding","url":"https://sane-av.github.io/glossary/?search=grounding","type":"Glossary","snippet":"Connecting to ground or to a conductive body that extends the ground connection. The connection is referred to as grounded.","tags":["Electrical"],"text":"Connecting to ground or to a conductive body that extends the ground connection. The connection is referred to as grounded."},{"title":"grounding conductor","url":"https://sane-av.github.io/glossary/?search=grounding%20conductor","type":"Glossary","snippet":"A conductor used to connect equipment or the grounding circuit of a wiring system to a grounding/ earth electrode or electrodes.","tags":["Electrical","Cabling"],"text":"A conductor used to connect equipment or the grounding circuit of a wiring system to a grounding/ earth electrode or electrodes."},{"title":"grounding electrode","url":"https://sane-av.github.io/glossary/?search=grounding%20electrode","type":"Glossary","snippet":"A conducting object through which a direct connection to earth (planet Earth) is established.","tags":["Electrical"],"text":"A conducting object through which a direct connection to earth (planet Earth) is established."},{"title":"grounding electrode conductor","url":"https://sane-av.github.io/glossary/?search=grounding%20electrode%20conductor","type":"Glossary","snippet":"The conductor used to connect the system grounded conductor or the equipment to a grounding electrode or to a point on the grounding electrode system.","tags":["Electrical"],"text":"The conductor used to connect the system grounded conductor or the equipment to a grounding electrode or to a point on the grounding electrode system."},{"title":"GMP (Group Management Protocol)","url":"https://sane-av.github.io/glossary/?search=Group%20Management%20Protocol","type":"Glossary","snippet":"A protocol that allows a host to inform its neighboring routers of its desire to start or stop receiving multicast transmissions.","tags":["Networking"],"text":"A protocol that allows a host to inform its neighboring routers of its desire to start or stop receiving multicast transmissions."},{"title":"group of pictures","url":"https://sane-av.github.io/glossary/?search=group%20of%20pictures","type":"Glossary","snippet":"A set of successive frames that are required to display a complete series in a digital video signal. It includes the visible picture, timing/sync information, and compression frames.","tags":["Video","Networking"],"text":"A set of successive frames that are required to display a complete series in a digital video signal. It includes the visible picture, timing/sync information, and compression frames."},{"title":"half-duplex communication","url":"https://sane-av.github.io/glossary/?search=half-duplex%20communication","type":"Glossary","snippet":"A form of bi-directional data transmission in which messages can only travel in one direction at any time.","tags":["Networking"],"text":"A form of bi-directional data transmission in which messages can only travel in one direction at any time."},{"title":"harmonic distortion","url":"https://sane-av.github.io/glossary/?search=harmonic%20distortion","type":"Glossary","snippet":"Signal distortion that arises when harmonics of an input signal are generated during processing and appear in the output together with the processed input signal.","tags":["General"],"text":"Signal distortion that arises when harmonics of an input signal are generated during processing and appear in the output together with the processed input signal."},{"title":"harmonics","url":"https://sane-av.github.io/glossary/?search=harmonics","type":"Glossary","snippet":"Higher frequencies that are a multiple of the fundamental frequency.","tags":["General"],"text":"Higher frequencies that are a multiple of the fundamental frequency."},{"title":"HD-15 connector","url":"https://sane-av.github.io/glossary/?search=HD-15%20connector","type":"Glossary","snippet":"Sometimes called a VGA connector, is a video connector that is typically associated with the output of an analog computer graphics card. It has three rows of five pins, which carry analog red, green, blue, and sync signals along with display data channel information. Not to be confused with two-row DB-15 connector.","tags":["Video","Cabling"],"text":"Sometimes called a VGA connector, is a video connector that is typically associated with the output of an analog computer graphics card. It has three rows of five pins, which carry analog red, green, blue, and sync signals along with display data channel information. Not to be confused with two-row DB-15 connector."},{"title":"HDBaseT","url":"https://sane-av.github.io/glossary/?search=HDBaseT","type":"Glossary","snippet":"A connectivity standard for the transmission of high-definition video, audio, DC power, Ethernet, and serial signaling, including USB and other protocols, over standard twisted-pair data cables such as Cat 5e and above.","tags":["Audio","Video","Networking","Cabling","Signal Processing"],"text":"A connectivity standard for the transmission of high-definition video, audio, DC power, Ethernet, and serial signaling, including USB and other protocols, over standard twisted-pair data cables such as Cat 5e and above."},{"title":"HDCP","url":"https://sane-av.github.io/glossary/?search=HDCP","type":"Glossary","snippet":"High-bandwidth digital content protection.","tags":["Video","Security"],"text":"High-bandwidth digital content protection."},{"title":"HDCP key","url":"https://sane-av.github.io/glossary/?search=HDCP%20key","type":"Glossary","snippet":"A number that a program uses to verify authenticity and encode/decode content. HDCP processes use multiple types of keys. These keys are strongly protected by Digital Content Protection, LLC.","tags":["Video","Security"],"text":"A number that a program uses to verify authenticity and encode/decode content. HDCP processes use multiple types of keys. These keys are strongly protected by Digital Content Protection, LLC."},{"title":"HDCP receiver/sink","url":"https://sane-av.github.io/glossary/?search=HDCP%20receiver%2Fsink","type":"Glossary","snippet":"A device that can receive and decode HDCP signals. A television is an example of a receiver.","tags":["Video","Security"],"text":"A device that can receive and decode HDCP signals. A television is an example of a receiver."},{"title":"HDCP repeater","url":"https://sane-av.github.io/glossary/?search=HDCP%20repeater","type":"Glossary","snippet":"A device that can receive HDCP signals and transmit them to another device, such as a switcher or distribution amplifier.","tags":["Audio","Video","Signal Processing","Security"],"text":"A device that can receive HDCP signals and transmit them to another device, such as a switcher or distribution amplifier."},{"title":"HDCP transmitter/source","url":"https://sane-av.github.io/glossary/?search=HDCP%20transmitter%2Fsource","type":"Glossary","snippet":"A device that can send HDCP-encoded signals and content. A Blu-ray Disc player is an example of an HDCP transmitter.","tags":["Video","Signal Processing","Security"],"text":"A device that can send HDCP-encoded signals and content. A Blu-ray Disc player is an example of an HDCP transmitter."},{"title":"HEAC (HDMI Ethernet Audio Control)","url":"https://sane-av.github.io/glossary/?search=HDMI%20Ethernet%20Audio%20Control","type":"Glossary","snippet":"In HDMI, the combining of HDMI Ethernet Channel (HEC) and Audio Return Channel (ARC) into one port or cable. See HDMI Ethernet Channel (HEC) and Audio Return Channel (ARC).","tags":["Audio","Video","Networking","Cabling"],"text":"In HDMI, the combining of HDMI Ethernet Channel (HEC) and Audio Return Channel (ARC) into one port or cable. See HDMI Ethernet Channel (HEC) and Audio Return Channel (ARC)."},{"title":"HEC (HDMI Ethernet Channel)","url":"https://sane-av.github.io/glossary/?search=HDMI%20Ethernet%20Channel","type":"Glossary","snippet":"Consolidates video, audio, and data streams into a single HDMI cable. A dedicated data channel enables high-speed, bi-directional networking to support future IP solutions and allow multiple devices to share an Internet connection.","tags":["Audio","Video","Networking","Cabling"],"text":"Consolidates video, audio, and data streams into a single HDMI cable. A dedicated data channel enables high-speed, bi-directional networking to support future IP solutions and allow multiple devices to share an Internet connection."},{"title":"HDTV","url":"https://sane-av.github.io/glossary/?search=HDTV","type":"Glossary","snippet":"High-definition television. Generally includes image resolutions above 1280×720.","tags":["Video"],"text":"High-definition television. Generally includes image resolutions above 1280×720."},{"title":"headend","url":"https://sane-av.github.io/glossary/?search=headend","type":"Glossary","snippet":"The equipment located at the start of a cable television distribution system where the signals are processed and combined prior to distribution.","tags":["Networking","Cabling"],"text":"The equipment located at the start of a cable television distribution system where the signals are processed and combined prior to distribution."},{"title":"headroom","url":"https://sane-av.github.io/glossary/?search=headroom","type":"Glossary","snippet":"The difference between the average performance level of a system and the maximum level it can produce. Usually measured in dB.","tags":["Audio"],"text":"The difference between the average performance level of a system and the maximum level it can produce. Usually measured in dB."},{"title":"heat load","url":"https://sane-av.github.io/glossary/?search=heat%20load","type":"Glossary","snippet":"Heat load is the heat released by a device during operation. It is measured in joules (or British thermal units).","tags":["General"],"text":"Heat load is the heat released by a device during operation. It is measured in joules (or British thermal units)."},{"title":"heat sink","url":"https://sane-av.github.io/glossary/?search=heat%20sink","type":"Glossary","snippet":"A device that absorbs and dissipates the heat produced by an object or process.","tags":["General"],"text":"A device that absorbs and dissipates the heat produced by an object or process."},{"title":"hemispheric polar pattern","url":"https://sane-av.github.io/glossary/?search=hemispheric%20polar%20pattern","type":"Glossary","snippet":"The dome shape of the region where some microphones will be most sensitive to sound. This is the pattern of boundary/pressure zone microphones.","tags":["Audio","Systems & Control"],"text":"The dome shape of the region where some microphones will be most sensitive to sound. This is the pattern of boundary/pressure zone microphones."},{"title":"hertz","url":"https://sane-av.github.io/glossary/?search=hertz","type":"Glossary","snippet":"The unit of frequency. 1Hz = 1 cycle per second.","tags":["General"],"text":"The unit of frequency. 1Hz = 1 cycle per second."},{"title":"hextet","url":"https://sane-av.github.io/glossary/?search=hextet","type":"Glossary","snippet":"A group of 16 bits, usually written as four lowercase hexadecimal digits (e.g., 0fe8). The 128-bit addresses used in IPv6 are written as eight hextets separated by colons (e.g., 2006:0fe8:85a3:0000:0002:8a2e:0a77:c082).","tags":["Networking"],"text":"A group of 16 bits, usually written as four lowercase hexadecimal digits (e.g., 0fe8). The 128-bit addresses used in IPv6 are written as eight hextets separated by colons (e.g., 2006:0fe8:85a3:0000:0002:8a2e:0a77:c082)."},{"title":"HDMI (High Definition Multimedia Interface)","url":"https://sane-av.github.io/glossary/?search=High%20Definition%20Multimedia%20Interface","type":"Glossary","snippet":"A point-to-point connection protocol between video devices for digital video and audio. HDMI signals include audio, control, Ethernet, and digital asset rights management information.","tags":["Audio","Video","Networking"],"text":"A point-to-point connection protocol between video devices for digital video and audio. HDMI signals include audio, control, Ethernet, and digital asset rights management information."},{"title":"HDR (high dynamic range)","url":"https://sane-av.github.io/glossary/?search=high%20dynamic%20range","type":"Glossary","snippet":"Digital images having a bit depth of at least 10 bits (1,024 levels) per channel. Standard dynamic range images have a bit depth of 8 bits (256 levels) per channel.","tags":["Audio","Video"],"text":"Digital images having a bit depth of at least 10 bits (1,024 levels) per channel. Standard dynamic range images have a bit depth of 8 bits (256 levels) per channel."},{"title":"HDCP (High-Bandwidth Digital Content Protection)","url":"https://sane-av.github.io/glossary/?search=High-Bandwidth%20Digital%20Content%20Protection","type":"Glossary","snippet":"A form of encryption developed by Intel to control digital audio and video content as it travels across Digital Video Interface (DVI), DisplayPort (DP), or High-Definition Multimedia Interface (HDMI) connections. It prevents transmission or interception of unencrypted HD content. Does not work across Serial Digital Interface (SDI) streams.","tags":["Audio","Video","Signal Processing","Security"],"text":"A form of encryption developed by Intel to control digital audio and video content as it travels across Digital Video Interface (DVI), DisplayPort (DP), or High-Definition Multimedia Interface (HDMI) connections. It prevents transmission or interception of unencrypted HD content. Does not work across Serial Digital Interface (SDI) streams."},{"title":"high-pass filter","url":"https://sane-av.github.io/glossary/?search=high-pass%20filter","type":"Glossary","snippet":"A circuit that allows signals above a specified frequency to pass unaltered while simultaneously attenuating frequencies below the specified limit.","tags":["Electrical","Signal Processing"],"text":"A circuit that allows signals above a specified frequency to pass unaltered while simultaneously attenuating frequencies below the specified limit."},{"title":"hiss","url":"https://sane-av.github.io/glossary/?search=hiss","type":"Glossary","snippet":"Broadband higher-frequency noise generated by random electron movement in the amplification stages of a system. In audio systems it is typically associated with poor system gain structure.","tags":["Audio"],"text":"Broadband higher-frequency noise generated by random electron movement in the amplification stages of a system. In audio systems it is typically associated with poor system gain structure."},{"title":"horn","url":"https://sane-av.github.io/glossary/?search=horn","type":"Glossary","snippet":"A flared-shape loudspeaker that reproduces mid to high frequencies.","tags":["Audio"],"text":"A flared-shape loudspeaker that reproduces mid to high frequencies."},{"title":"hot plug","url":"https://sane-av.github.io/glossary/?search=hot%20plug","type":"Glossary","snippet":"1. A low-level signal sent by an EDID source that indicates whether a sink or display is connected. 2. A system that can detect and respond to devices being connected or disconnected during normal operations (e.g., USB). 3. Plugging or unplugging equipment while it is still powered up.","tags":["Video","Signal Processing"],"text":"1. A low-level signal sent by an EDID source that indicates whether a sink or display is connected. 2. A system that can detect and respond to devices being connected or disconnected during normal operations (e.g., USB). 3. Plugging or unplugging equipment while it is still powered up."},{"title":"hue","url":"https://sane-av.github.io/glossary/?search=hue","type":"Glossary","snippet":"The attribute of a color that represents its position in a defined color space or on the visible spectrum. Hue is usually described with a color name such as “red,” “blue,” “yellow,” or “purple.” It is one of the three attributes that define color; the other two are luminance and chroma.","tags":["Video"],"text":"The attribute of a color that represents its position in a defined color space or on the visible spectrum. Hue is usually described with a color name such as “red,” “blue,” “yellow,” or “purple.” It is one of the three attributes that define color; the other two are luminance and chroma."},{"title":"hum","url":"https://sane-av.github.io/glossary/?search=hum","type":"Glossary","snippet":"Undesirable (usually 50 to 60Hz-plus harmonics) noise emanating from an audio device or evidenced by a rolling hum bar on a display.","tags":["Audio","Video"],"text":"Undesirable (usually 50 to 60Hz-plus harmonics) noise emanating from an audio device or evidenced by a rolling hum bar on a display."},{"title":"I/O port","url":"https://sane-av.github.io/glossary/?search=I%2FO%20port","type":"Glossary","snippet":"Input and/or output port. A connection port on a device for handling input and/or output signals.","tags":["General"],"text":"Input and/or output port. A connection port on a device for handling input and/or output signals."},{"title":"IEEE","url":"https://sane-av.github.io/glossary/?search=IEEE","type":"Glossary","snippet":"The Institute of Electrical and Electronics Engineers.","tags":["Standards"],"text":"The Institute of Electrical and Electronics Engineers."},{"title":"IGBT","url":"https://sane-av.github.io/glossary/?search=IGBT","type":"Glossary","snippet":"The insulated-gate bipolar transistor (IGBT) is a high-power, three-terminal semiconductor device similar in structure to a thyristor. It is primarily used for high-speed switching applications such as inverters for variable-speed motor control, switch mode power supplies, and reverse phase-control dimming.","tags":["Electrical","Lighting"],"text":"The insulated-gate bipolar transistor (IGBT) is a high-power, three-terminal semiconductor device similar in structure to a thyristor. It is primarily used for high-speed switching applications such as inverters for variable-speed motor control, switch mode power supplies, and reverse phase-control dimming."},{"title":"illuminance","url":"https://sane-av.github.io/glossary/?search=illuminance","type":"Glossary","snippet":"The amount of light falling on a surface, measured in lux (lx) or foot-candle (fc). 1 foot-candle = 10.76 lux.","tags":["Video","Lighting"],"text":"The amount of light falling on a surface, measured in lux (lx) or foot-candle (fc). 1 foot-candle = 10.76 lux."},{"title":"ICT (image constraint token)","url":"https://sane-av.github.io/glossary/?search=image%20constraint%20token","type":"Glossary","snippet":"A digital flag signal incorporated into some high-definition digital video streams. If present, the video stream can be decoded at full resolution only on HDCP-enabled devices.","tags":["Video","Security"],"text":"A digital flag signal incorporated into some high-definition digital video streams. If present, the video stream can be decoded at full resolution only on HDCP-enabled devices."},{"title":"image resolution","url":"https://sane-av.github.io/glossary/?search=image%20resolution","type":"Glossary","snippet":"The total number of pixels in the image. It is normally expressed as the number of horizontal pixels multiplied by the number of vertical pixels, e.g., 1920×1080.","tags":["Video"],"text":"The total number of pixels in the image. It is normally expressed as the number of horizontal pixels multiplied by the number of vertical pixels, e.g., 1920×1080."},{"title":"imager","url":"https://sane-av.github.io/glossary/?search=imager","type":"Glossary","snippet":"A light-sensitive electronic device behind a camera’s lens, usually made up of thousands of sensors that convert the light input into an electrical output.","tags":["Video"],"text":"A light-sensitive electronic device behind a camera’s lens, usually made up of thousands of sensors that convert the light input into an electrical output."},{"title":"impedance","url":"https://sane-av.github.io/glossary/?search=impedance","type":"Glossary","snippet":"The total opposition that a circuit presents to an alternating current. It includes resistance (R), inductive reactance (XL), and capacitive reactance (XC ). Impedance is measured in ohms (Ω). Its symbol is Z. Formula:","tags":["Electrical"],"text":"The total opposition that a circuit presents to an alternating current. It includes resistance (R), inductive reactance (XL), and capacitive reactance (XC ). Impedance is measured in ohms (Ω). Its symbol is Z. Formula:"},{"title":"impedance matching","url":"https://sane-av.github.io/glossary/?search=impedance%20matching","type":"Glossary","snippet":"Having impedance values on an input and output that facilitate the most efficient transfer of a signal. It does not necessarily mean having comparable impedances on an input and an output.","tags":["Electrical"],"text":"Having impedance values on an input and output that facilitate the most efficient transfer of a signal. It does not necessarily mean having comparable impedances on an input and an output."},{"title":"impedance meter","url":"https://sane-av.github.io/glossary/?search=impedance%20meter","type":"Glossary","snippet":"Device used to measure the impedance of an electrical circuit.","tags":["Electrical"],"text":"Device used to measure the impedance of an electrical circuit."},{"title":"incident","url":"https://sane-av.github.io/glossary/?search=incident","type":"Glossary","snippet":"An event that threatens or adversely affects AV and information systems or the data that resides on them.","tags":["Security"],"text":"An event that threatens or adversely affects AV and information systems or the data that resides on them."},{"title":"inductance","url":"https://sane-av.github.io/glossary/?search=inductance","type":"Glossary","snippet":"The magnetic property of a circuit that opposes any change in current, represented by the symbol L and measured in henrys (H).","tags":["Electrical"],"text":"The magnetic property of a circuit that opposes any change in current, represented by the symbol L and measured in henrys (H)."},{"title":"induction","url":"https://sane-av.github.io/glossary/?search=induction","type":"Glossary","snippet":"The influence exerted on a conductor by a changing magnetic field.","tags":["Electrical"],"text":"The influence exerted on a conductor by a changing magnetic field."},{"title":"inductive reactance (X L)","url":"https://sane-av.github.io/glossary/?search=inductive%20reactance%20(X%20L)","type":"Glossary","snippet":"Opposition to the current flow offered by the inductance of a circuit. Inductive reactance is measured in ohms (Ω). Its symbol is XL. The inductive reactance in a circuit is directly proportional to the frequency of the current.","tags":["Electrical"],"text":"Opposition to the current flow offered by the inductance of a circuit. Inductive reactance is measured in ohms (Ω). Its symbol is XL. The inductive reactance in a circuit is directly proportional to the frequency of the current."},{"title":"InfoFrames","url":"https://sane-av.github.io/glossary/?search=InfoFrames","type":"Glossary","snippet":"Structured packets of data that carry information regarding aspects of audio and video transmission, as defined by the EIA/CEA-861 standard. Using this structure, a frame-by-frame summary is sent to the display, permitting selection of appropriate display modes automatically. InfoFrames typically include auxiliary video information, generic vendor-specific source product description, MPEG, and audio information.","tags":["Audio","Video","Networking","Standards"],"text":"Structured packets of data that carry information regarding aspects of audio and video transmission, as defined by the EIA/CEA-861 standard. Using this structure, a frame-by-frame summary is sent to the display, permitting selection of appropriate display modes automatically. InfoFrames typically include auxiliary video information, generic vendor-specific source product description, MPEG, and audio information."},{"title":"IR (infrared)","url":"https://sane-av.github.io/glossary/?search=infrared","type":"Glossary","snippet":"The range of nonvisible light frequencies below the red end of the visible spectrum. IR signal transmission requires an uninterrupted signal path between transmitter and receiver.","tags":["Lighting"],"text":"The range of nonvisible light frequencies below the red end of the visible spectrum. IR signal transmission requires an uninterrupted signal path between transmitter and receiver."},{"title":"input","url":"https://sane-av.github.io/glossary/?search=input","type":"Glossary","snippet":"A connection point that receives information from another piece of equipment.","tags":["General"],"text":"A connection point that receives information from another piece of equipment."},{"title":"insider threat","url":"https://sane-av.github.io/glossary/?search=insider%20threat","type":"Glossary","snippet":"A vector of risk to an organization’s AV or information systems that comes from within the organization, such as employees, contractors, or other associates. These parties generally have increased access to systems and a greater knowledge of their defenses.","tags":["Security"],"text":"A vector of risk to an organization’s AV or information systems that comes from within the organization, such as employees, contractors, or other associates. These parties generally have increased access to systems and a greater knowledge of their defenses."},{"title":"insulation","url":"https://sane-av.github.io/glossary/?search=insulation","type":"Glossary","snippet":"A material of high dielectric strength used to isolate the flow of electric current between conductors.","tags":["Electrical"],"text":"A material of high dielectric strength used to isolate the flow of electric current between conductors."},{"title":"ISDN (Integrated Services Digital Network)","url":"https://sane-av.github.io/glossary/?search=Integrated%20Services%20Digital%20Network","type":"Glossary","snippet":"A communications standard for transmitting data over digital telephone lines.","tags":["Networking"],"text":"A communications standard for transmitting data over digital telephone lines."},{"title":"IP (intellectual property)","url":"https://sane-av.github.io/glossary/?search=intellectual%20property","type":"Glossary","snippet":"A type of property that includes the creations of the human intellect. It includes ideas; written material such as books, articles, poems, and essays; designs including plans, specifications, diagrams, sketches, and program code; images such as photographs, graphic arts, and other artworks; music and songs; and movie and video . Intellectual property rights are usually asserted through the use of patents, trademarks, copyrights, and trade secrets. All IP used in the design, execution, and operation of an AV installation must be correctly licensed from each of the owners of that IP.","tags":["Video"],"text":"A type of property that includes the creations of the human intellect. It includes ideas; written material such as books, articles, poems, and essays; designs including plans, specifications, diagrams, sketches, and program code; images such as photographs, graphic arts, and other artworks; music and songs; and movie and video . Intellectual property rights are usually asserted through the use of patents, trademarks, copyrights, and trade secrets. All IP used in the design, execution, and operation of an AV installation must be correctly licensed from each of the owners of that IP."},{"title":"intelligibility","url":"https://sane-av.github.io/glossary/?search=intelligibility","type":"Glossary","snippet":"A sound installation’s ability to produce an accurate reproduction of sound, allowing listeners to identify words and sentence structure.","tags":["Acoustics"],"text":"A sound installation’s ability to produce an accurate reproduction of sound, allowing listeners to identify words and sentence structure."},{"title":"interlaced scanning","url":"https://sane-av.github.io/glossary/?search=interlaced%20scanning","type":"Glossary","snippet":"The scanning process that alternately displays the odd and even lines of a video frame to construct a full frame of video signal.","tags":["Video"],"text":"The scanning process that alternately displays the odd and even lines of a video frame to construct a full frame of video signal."},{"title":"internal configuration","url":"https://sane-av.github.io/glossary/?search=internal%20configuration","type":"Glossary","snippet":"Refers to the local setup and customization of management or control of a device.","tags":["Systems & Control"],"text":"Refers to the local setup and customization of management or control of a device."},{"title":"ICANN (Internet Corporation for Assigned Names and Numbers)","url":"https://sane-av.github.io/glossary/?search=Internet%20Corporation%20for%20Assigned%20Names%20and%20Numbers","type":"Glossary","snippet":"An organization chartered to oversee several Internet-related tasks. ICANN manages Domain Name System (DNS) policy, including the top-level domain space for the Internet.","tags":["Networking","Standards"],"text":"An organization chartered to oversee several Internet-related tasks. ICANN manages Domain Name System (DNS) policy, including the top-level domain space for the Internet."},{"title":"IGMP (Internet Group Management Protocol)","url":"https://sane-av.github.io/glossary/?search=Internet%20Group%20Management%20Protocol","type":"Glossary","snippet":"The group management protocol for IPv4. IGMPv1 allowed individual clients to subscribe to a multicast channel. IGMPv2 and IGMPv3 added the ability to unsubscribe from a multicast channel.","tags":["Networking"],"text":"The group management protocol for IPv4. IGMPv1 allowed individual clients to subscribe to a multicast channel. IGMPv2 and IGMPv3 added the ability to unsubscribe from a multicast channel."},{"title":"Internet of Things","url":"https://sane-av.github.io/glossary/?search=Internet%20of%20Things","type":"Glossary","snippet":"Refers to a situation where network connectivity and computing capability have been extended to include objects, sensors, and other devices, allowing these devices to exchange data.","tags":["Systems & Control"],"text":"Refers to a situation where network connectivity and computing capability have been extended to include objects, sensors, and other devices, allowing these devices to exchange data."},{"title":"IP (Internet Protocol)","url":"https://sane-av.github.io/glossary/?search=Internet%20Protocol","type":"Glossary","snippet":"A TCP/IP protocol defined in the IETF standard RFC 791. IP defines rules for addressing, packaging, fragmenting, and routing data sent across an IP network. IP falls under the Internet layer of the TCP/ IP protocol stack and the Network layer (layer 3) of the OSI Model.","tags":["Networking","Standards"],"text":"A TCP/IP protocol defined in the IETF standard RFC 791. IP defines rules for addressing, packaging, fragmenting, and routing data sent across an IP network. IP falls under the Internet layer of the TCP/ IP protocol stack and the Network layer (layer 3) of the OSI Model."},{"title":"IPTV (Internet Protocol Television)","url":"https://sane-av.github.io/glossary/?search=Internet%20Protocol%20Television","type":"Glossary","snippet":"A system that delivers television services over an IP network such as a LAN or the Internet.","tags":["Networking"],"text":"A system that delivers television services over an IP network such as a LAN or the Internet."},{"title":"inverse square law","url":"https://sane-av.github.io/glossary/?search=inverse%20square%20law","type":"Glossary","snippet":"The law of physics stating that a physical quantity or strength is inversely proportional to the square of the distance from the source of that physical quantity.","tags":["Standards"],"text":"The law of physics stating that a physical quantity or strength is inversely proportional to the square of the distance from the source of that physical quantity."},{"title":"IoT","url":"https://sane-av.github.io/glossary/?search=IoT","type":"Glossary","snippet":"Refers to a situation where network connectivity and computing capability have been extended to include objects, sensors, and other devices, allowing these devices to exchange data. Abbreviation for Internet of Things.","tags":["Systems & Control"],"text":"Refers to a situation where network connectivity and computing capability have been extended to include objects, sensors, and other devices, allowing these devices to exchange data. Abbreviation for Internet of Things."},{"title":"IP","url":"https://sane-av.github.io/glossary/?search=IP","type":"Glossary","snippet":"Abbreviation for two distinct terms used in AV contexts. (1) Internet Protocol: a TCP/IP protocol defined in IETF RFC 791 that defines rules for addressing, packaging, fragmenting, and routing data across a network; it falls under the Internet layer of the TCP/IP stack and layer 3 of the OSI Model. (2) Intellectual property: a type of property covering the creations of the human intellect, including written material, designs, images, music, and software. IP rights are typically asserted through patents, trademarks, copyrights, and trade secrets. Context determines which meaning applies.","tags":["General"],"text":"Abbreviation for two distinct terms used in AV contexts. (1) Internet Protocol: a TCP/IP protocol defined in IETF RFC 791 that defines rules for addressing, packaging, fragmenting, and routing data across a network; it falls under the Internet layer of the TCP/IP stack and layer 3 of the OSI Model. (2) Intellectual property: a type of property covering the creations of the human intellect, including written material, designs, images, music, and software. IP rights are typically asserted through patents, trademarks, copyrights, and trade secrets. Context determines which meaning applies."},{"title":"IR","url":"https://sane-av.github.io/glossary/?search=IR","type":"Glossary","snippet":"The range of nonvisible light frequencies below the red end of the visible spectrum. IR signal transmission requires an uninterrupted signal path between transmitter and receiver. Abbreviation for infrared.","tags":["Lighting"],"text":"The range of nonvisible light frequencies below the red end of the visible spectrum. IR signal transmission requires an uninterrupted signal path between transmitter and receiver. Abbreviation for infrared."},{"title":"IG (isolated ground)","url":"https://sane-av.github.io/glossary/?search=isolated%20ground","type":"Glossary","snippet":"An equipment grounding method permitted by the North American NEC for reducing electrical noise (electromagnetic interference) on the grounding circuit. The isolation between IG receptacles and circuits and the normal equipment grounding is maintained up to the point of the service entrance (or a separately derived system) where the grounded (neutral) conductor, equipment grounding, and isolated equipment grounding conductor are bonded together and to earth/ground (planet Earth).","tags":["Electrical"],"text":"An equipment grounding method permitted by the North American NEC for reducing electrical noise (electromagnetic interference) on the grounding circuit. The isolation between IG receptacles and circuits and the normal equipment grounding is maintained up to the point of the service entrance (or a separately derived system) where the grounded (neutral) conductor, equipment grounding, and isolated equipment grounding conductor are bonded together and to earth/ground (planet Earth)."},{"title":"isolated grounding circuit","url":"https://sane-av.github.io/glossary/?search=isolated%20grounding%20circuit","type":"Glossary","snippet":"A circuit that allows an equipment enclosure to be isolated from the raceway containing circuits. The equipment on the circuit is grounded via an insulated earthing/grounding conductor.","tags":["Electrical","Cabling"],"text":"A circuit that allows an equipment enclosure to be isolated from the raceway containing circuits. The equipment on the circuit is grounded via an insulated earthing/grounding conductor."},{"title":"isolated receptacle","url":"https://sane-av.github.io/glossary/?search=isolated%20receptacle","type":"Glossary","snippet":"A power receptacle or mains power outlet in which the grounding terminal is purposely insulated from the receptacle-mounting means. In North America isolated receptacles are identified by a triangle engraved on the face. The receptacle (and so the equipment plugged into the receptacle) is grounded via an insulated earthing/grounding conductor.","tags":["Electrical"],"text":"A power receptacle or mains power outlet in which the grounding terminal is purposely insulated from the receptacle-mounting means. In North America isolated receptacles are identified by a triangle engraved on the face. The receptacle (and so the equipment plugged into the receptacle) is grounded via an insulated earthing/grounding conductor."},{"title":"jacket","url":"https://sane-av.github.io/glossary/?search=jacket","type":"Glossary","snippet":"Outside covering used to protect cable conductors and their shielding.","tags":["Electrical","Cabling"],"text":"Outside covering used to protect cable conductors and their shielding."},{"title":"junction box","url":"https://sane-av.github.io/glossary/?search=junction%20box","type":"Glossary","snippet":"A structure for enclosing the junction of electrical wires and cables. In North America a junction box can be used as a termination point with a custom connector plate or interface plate. A junction box can also be installed and used as a pull box for longer cable runs.","tags":["Electrical","Cabling"],"text":"A structure for enclosing the junction of electrical wires and cables. In North America a junction box can be used as a termination point with a custom connector plate or interface plate. A junction box can also be installed and used as a pull box for longer cable runs."},{"title":"keystone error","url":"https://sane-av.github.io/glossary/?search=keystone%20error","type":"Glossary","snippet":"The trapezoidal distortion of an image due to the projection device being at an angle to the plane of the screen.","tags":["Video"],"text":"The trapezoidal distortion of an image due to the projection device being at an angle to the plane of the screen."},{"title":"lamp","url":"https://sane-av.github.io/glossary/?search=lamp","type":"Glossary","snippet":"The light source in some luminaires and projectors.","tags":["Video","Lighting"],"text":"The light source in some luminaires and projectors."},{"title":"latency","url":"https://sane-av.github.io/glossary/?search=latency","type":"Glossary","snippet":"Response time of a system. The delay between an input being received by a system and the corresponding output being generated. Measured in seconds.","tags":["General"],"text":"Response time of a system. The delay between an input being received by a system and the corresponding output being generated. Measured in seconds."},{"title":"lavalier","url":"https://sane-av.github.io/glossary/?search=lavalier","type":"Glossary","snippet":"A small microphone usually worn either around the neck or attached to apparel. Derived from the name of an item of jewelry worn as a pendant.","tags":["Audio"],"text":"A small microphone usually worn either around the neck or attached to apparel. Derived from the name of an item of jewelry worn as a pendant."},{"title":"law of conservation of energy","url":"https://sane-av.github.io/glossary/?search=law%20of%20conservation%20of%20energy","type":"Glossary","snippet":"States that energy cannot be created or destroyed. Energy can be transformed from one form to another and transferred from one body to another, but the total amount of energy remains constant.","tags":["Standards"],"text":"States that energy cannot be created or destroyed. Energy can be transformed from one form to another and transferred from one body to another, but the total amount of energy remains constant."},{"title":"lenticular screen","url":"https://sane-av.github.io/glossary/?search=lenticular%20screen","type":"Glossary","snippet":"A screen surface characterized by embossing designed to transmit or reflect maximum light over wide horizontal, but narrow vertical, angles.","tags":["General"],"text":"A screen surface characterized by embossing designed to transmit or reflect maximum light over wide horizontal, but narrow vertical, angles."},{"title":"Li-Fi","url":"https://sane-av.github.io/glossary/?search=Li-Fi","type":"Glossary","snippet":"A wireless communication technology that carries data using modulated light, often using high-frequency modulation of the luminaires illuminating a space.","tags":["Lighting"],"text":"A wireless communication technology that carries data using modulated light, often using high-frequency modulation of the luminaires illuminating a space."},{"title":"lighting fixture","url":"https://sane-av.github.io/glossary/?search=lighting%20fixture","type":"Glossary","snippet":"A lighting instrument or luminaire. Sometimes called a fixture.","tags":["Cabling","Lighting"],"text":"A lighting instrument or luminaire. Sometimes called a fixture."},{"title":"limiter","url":"https://sane-av.github.io/glossary/?search=limiter","type":"Glossary","snippet":"1. A signal processor that limits the amplitude of a signal to a preset level. 2. An audio signal processor that functions like a compressor except that signals exceeding the threshold level are reduced at ratios of 10:1 or greater.","tags":["Audio","Signal Processing","Systems & Control"],"text":"1. A signal processor that limits the amplitude of a signal to a preset level. 2. An audio signal processor that functions like a compressor except that signals exceeding the threshold level are reduced at ratios of 10:1 or greater."},{"title":"limiter ratio","url":"https://sane-av.github.io/glossary/?search=limiter%20ratio","type":"Glossary","snippet":"Defines how much an audio limiter will compress signals that exceed its threshold. The limiter compresses only the portion of the signal that exceeds its threshold.","tags":["Audio"],"text":"Defines how much an audio limiter will compress signals that exceed its threshold. The limiter compresses only the portion of the signal that exceeds its threshold."},{"title":"limiter threshold","url":"https://sane-av.github.io/glossary/?search=limiter%20threshold","type":"Glossary","snippet":"Defines which portions of a signal the limiter will affect. All signals at levels below or equal to the threshold will pass through the limiter unchanged. All signals above the threshold will be compressed.","tags":["Audio"],"text":"Defines which portions of a signal the limiter will affect. All signals at levels below or equal to the threshold will pass through the limiter unchanged. All signals above the threshold will be compressed."},{"title":"line conditioner","url":"https://sane-av.github.io/glossary/?search=line%20conditioner","type":"Glossary","snippet":"A device that conditions the quality of power being fed to equipment by regulating the voltage and eliminating line noise. Also known as a power conditioner or power line conditioner.","tags":["Electrical"],"text":"A device that conditions the quality of power being fed to equipment by regulating the voltage and eliminating line noise. Also known as a power conditioner or power line conditioner."},{"title":"line driver","url":"https://sane-av.github.io/glossary/?search=line%20driver","type":"Glossary","snippet":"An amplifier used to compensate for signal attenuation created by cable impedance.","tags":["Audio","Electrical","Cabling","Signal Processing"],"text":"An amplifier used to compensate for signal attenuation created by cable impedance."},{"title":"line level","url":"https://sane-av.github.io/glossary/?search=line%20level","type":"Glossary","snippet":"The specified strength of an audio signal used to transmit analog audio between the elements of an audio system. This is generally considered to be approximately 1V at 1kHz into a 600Ω impedance.","tags":["Audio","Electrical"],"text":"The specified strength of an audio signal used to transmit analog audio between the elements of an audio system. This is generally considered to be approximately 1V at 1kHz into a 600Ω impedance."},{"title":"LCD (liquid crystal display)","url":"https://sane-av.github.io/glossary/?search=liquid%20crystal%20display","type":"Glossary","snippet":"A video display technology that uses light transmission through polarizing liquid crystals to display an image.","tags":["Video"],"text":"A video display technology that uses light transmission through polarizing liquid crystals to display an image."},{"title":"liquid crystal on silicon","url":"https://sane-av.github.io/glossary/?search=liquid%20crystal%20on%20silicon","type":"Glossary","snippet":"A reflective liquid crystal imaging technology. A liquid crystal layer is applied to a reflective complementary metal oxide semiconductor (CMOS) mirror substrate. The embedded CMOS circuitry controls the reflectivity of the liquid crystal pixels.","tags":["Video","Electrical"],"text":"A reflective liquid crystal imaging technology. A liquid crystal layer is applied to a reflective complementary metal oxide semiconductor (CMOS) mirror substrate. The embedded CMOS circuitry controls the reflectivity of the liquid crystal pixels."},{"title":"listed","url":"https://sane-av.github.io/glossary/?search=listed","type":"Glossary","snippet":"Equipment, materials, or services included in a list published by a recognized testing laboratory. The term is usually applied to products or processes tested by the U.S. Underwriters Laboratories (UL).","tags":["Project Management"],"text":"Equipment, materials, or services included in a list published by a recognized testing laboratory. The term is usually applied to products or processes tested by the U.S. Underwriters Laboratories (UL)."},{"title":"load center","url":"https://sane-av.github.io/glossary/?search=load%20center","type":"Glossary","snippet":"An electrical industry term used to identify a lighting and appliance electrical distribution board in residential and light-commercial applications.","tags":["Electrical"],"text":"An electrical industry term used to identify a lighting and appliance electrical distribution board in residential and light-commercial applications."},{"title":"LAN (local area network)","url":"https://sane-av.github.io/glossary/?search=local%20area%20network","type":"Glossary","snippet":"1. A computer network connecting devices within a confined geographical area, such as a building. 2. A Data Link-layer (layer 2) network.","tags":["Networking"],"text":"1. A computer network connecting devices within a confined geographical area, such as a building. 2. A Data Link-layer (layer 2) network."},{"title":"local monitor","url":"https://sane-av.github.io/glossary/?search=local%20monitor","type":"Glossary","snippet":"A local device used to monitor the signal from a system.","tags":["General"],"text":"A local device used to monitor the signal from a system."},{"title":"logarithm","url":"https://sane-av.github.io/glossary/?search=logarithm","type":"Glossary","snippet":"The exponent of 10 that equals the value of a number.","tags":["General"],"text":"The exponent of 10 that equals the value of a number."},{"title":"logic network diagram","url":"https://sane-av.github.io/glossary/?search=logic%20network%20diagram","type":"Glossary","snippet":"A project management tool that aids in sequencing and ultimately scheduling a project’s activities and milestones. It represents a project’s critical path as well as the scope for the project.","tags":["Project Management"],"text":"A project management tool that aids in sequencing and ultimately scheduling a project’s activities and milestones. It represents a project’s critical path as well as the scope for the project."},{"title":"lossless compression","url":"https://sane-av.github.io/glossary/?search=lossless%20compression","type":"Glossary","snippet":"A process that compresses data without losing any information.","tags":["General"],"text":"A process that compresses data without losing any information."},{"title":"lossy compression","url":"https://sane-av.github.io/glossary/?search=lossy%20compression","type":"Glossary","snippet":"A form of compression that produces an approximation of the original data by eliminating noncritical or redundant information.","tags":["General"],"text":"A form of compression that produces an approximation of the original data by eliminating noncritical or redundant information."},{"title":"loudspeaker","url":"https://sane-av.github.io/glossary/?search=loudspeaker","type":"Glossary","snippet":"A transducer that converts electrical energy into acoustical energy.","tags":["Acoustics","Audio"],"text":"A transducer that converts electrical energy into acoustical energy."},{"title":"loudspeaker circuit","url":"https://sane-av.github.io/glossary/?search=loudspeaker%20circuit","type":"Glossary","snippet":"A group of wired loudspeakers.","tags":["Audio","Electrical"],"text":"A group of wired loudspeakers."},{"title":"low smoke zero halogen cable","url":"https://sane-av.github.io/glossary/?search=low%20smoke%20zero%20halogen%20cable","type":"Glossary","snippet":"A type of cable with insulation and sheathing that produces only low levels of smoke and no halogen products on combustion. Suitable for use in ventilation plenum spaces.","tags":["Electrical","Cabling"],"text":"A type of cable with insulation and sheathing that produces only low levels of smoke and no halogen products on combustion. Suitable for use in ventilation plenum spaces."},{"title":"low voltage","url":"https://sane-av.github.io/glossary/?search=low%20voltage","type":"Glossary","snippet":"An ambiguous term. It may mean less than 70V AC to an AV technician, while an electrician may use the same term to describe circuits less than 600V or 1kV AC. The meaning of the term may also be determined by the authority having jurisdiction (AHJ).","tags":["Electrical","Project Management"],"text":"An ambiguous term. It may mean less than 70V AC to an AV technician, while an electrician may use the same term to describe circuits less than 600V or 1kV AC. The meaning of the term may also be determined by the authority having jurisdiction (AHJ)."},{"title":"low-pass filter","url":"https://sane-av.github.io/glossary/?search=low-pass%20filter","type":"Glossary","snippet":"A circuit that allows signals below a specified frequency to pass unaltered while simultaneously attenuating frequencies above the one specified.","tags":["Electrical","Signal Processing"],"text":"A circuit that allows signals below a specified frequency to pass unaltered while simultaneously attenuating frequencies above the one specified."},{"title":"lumen","url":"https://sane-av.github.io/glossary/?search=lumen","type":"Glossary","snippet":"The unit of luminous flux. A measure of the total quantity of visible light emitted from light source per unit of time. Its symbol is lm.","tags":["Lighting"],"text":"The unit of luminous flux. A measure of the total quantity of visible light emitted from light source per unit of time. Its symbol is lm."},{"title":"luminaire","url":"https://sane-av.github.io/glossary/?search=luminaire","type":"Glossary","snippet":"A lighting instrument. Consists of a light source, optical system, housing, and mounting mechanism.","tags":["Cabling","Lighting"],"text":"A lighting instrument. Consists of a light source, optical system, housing, and mounting mechanism."},{"title":"Y (luminance)","url":"https://sane-av.github.io/glossary/?search=luminance","type":"Glossary","snippet":"Also called luma, the brightness component of a combined video signal that includes synchronization, color, and brightness information. Its symbol is Y.","tags":["Video"],"text":"Also called luma, the brightness component of a combined video signal that includes synchronization, color, and brightness information. Its symbol is Y."},{"title":"lux","url":"https://sane-av.github.io/glossary/?search=lux","type":"Glossary","snippet":"The international unit of illuminance. The incident light measured when 1 lumen of light is spread over an area of 1 square meter. Its symbol is lx. 10.76 lux = 1 foot-candle.","tags":["Video","Lighting","Security"],"text":"The international unit of illuminance. The incident light measured when 1 lumen of light is spread over an area of 1 square meter. Its symbol is lx. 10.76 lux = 1 foot-candle."},{"title":"MAC address","url":"https://sane-av.github.io/glossary/?search=MAC%20address","type":"Glossary","snippet":"The unique 48-bit hardware address of the media access controller on a network device. Usually written as six groups of two hexadecimal numbers, separated by a hyphen or colon (e.g., 01-23-45-67-89-ab or 01:23:45:67:89:ab).","tags":["Networking"],"text":"The unique 48-bit hardware address of the media access controller on a network device. Usually written as six groups of two hexadecimal numbers, separated by a hyphen or colon (e.g., 01-23-45-67-89-ab or 01:23:45:67:89:ab)."},{"title":"mains buzz","url":"https://sane-av.github.io/glossary/?search=mains%20buzz","type":"Glossary","snippet":"A mixture of higher-order harmonics of the 50Hz or 60Hz noise (hum) originating from the AC mains power system and audible in a sound system.","tags":["Audio","Electrical"],"text":"A mixture of higher-order harmonics of the 50Hz or 60Hz noise (hum) originating from the AC mains power system and audible in a sound system."},{"title":"malware","url":"https://sane-av.github.io/glossary/?search=malware","type":"Glossary","snippet":"Software that threatens the operation of an AV or information system by performing an unauthorized function.","tags":["Security"],"text":"Software that threatens the operation of an AV or information system by performing an unauthorized function."},{"title":"matrix decoder","url":"https://sane-av.github.io/glossary/?search=matrix%20decoder","type":"Glossary","snippet":"A video decoder that extracts red, green, and blue signals from either composite or Y, R-Y, and B-Y signals.","tags":["Video"],"text":"A video decoder that extracts red, green, and blue signals from either composite or Y, R-Y, and B-Y signals."},{"title":"matrix switcher","url":"https://sane-av.github.io/glossary/?search=matrix%20switcher","type":"Glossary","snippet":"An electronic switching device with multiple inputs and outputs. The matrix allows any input to be connected to any one or more of the outputs.","tags":["Signal Processing"],"text":"An electronic switching device with multiple inputs and outputs. The matrix allows any input to be connected to any one or more of the outputs."},{"title":"matte-white screen","url":"https://sane-av.github.io/glossary/?search=matte-white%20screen","type":"Glossary","snippet":"A screen that uniformly disperses light, both horizontally and vertically, creating a wide viewing cone and wide viewing angle.","tags":["Audio","Video"],"text":"A screen that uniformly disperses light, both horizontally and vertically, creating a wide viewing cone and wide viewing angle."},{"title":"MTU (maximum transmission unit)","url":"https://sane-av.github.io/glossary/?search=maximum%20transmission%20unit","type":"Glossary","snippet":"The size in bytes of the largest frame that can pass over a Data Link-layer (layer 2) connection. Header information must be included within the MTU.","tags":["Networking"],"text":"The size in bytes of the largest frame that can pass over a Data Link-layer (layer 2) connection. Header information must be included within the MTU."},{"title":"MCB","url":"https://sane-av.github.io/glossary/?search=MCB","type":"Glossary","snippet":"Miniature circuit breaker. Small-format circuit breakers used to protect branch loads in electrical distribution panels.","tags":["Electrical"],"text":"Miniature circuit breaker. Small-format circuit breakers used to protect branch loads in electrical distribution panels."},{"title":"mechanical switcher","url":"https://sane-av.github.io/glossary/?search=mechanical%20switcher","type":"Glossary","snippet":"A switch that mechanically opens and closes to connect circuit elements. It functions like a wall switch, meaning there is a mechanical connection or disconnection.","tags":["Electrical"],"text":"A switch that mechanically opens and closes to connect circuit elements. It functions like a wall switch, meaning there is a mechanical connection or disconnection."},{"title":"MEMS","url":"https://sane-av.github.io/glossary/?search=MEMS","type":"Glossary","snippet":"Mechanical devices built directly onto silicon chips using the same fabrication processes as microprocessors and memory systems. Best known as the digital micromirror devices (DMD) used for light switching in DLP projectors. Abbreviation for microelectromechanical systems.","tags":["General"],"text":"Mechanical devices built directly onto silicon chips using the same fabrication processes as microprocessors and memory systems. Best known as the digital micromirror devices (DMD) used for light switching in DLP projectors. Abbreviation for microelectromechanical systems."},{"title":"MEMS microphone","url":"https://sane-av.github.io/glossary/?search=MEMS%20microphone","type":"Glossary","snippet":"A microphone built using MEMS technology. Generally, MEMS implementations of either condenser or piezo-electric microphones.","tags":["Audio"],"text":"A microphone built using MEMS technology. Generally, MEMS implementations of either condenser or piezo-electric microphones."},{"title":"mesh topology","url":"https://sane-av.github.io/glossary/?search=mesh%20topology","type":"Glossary","snippet":"A network where each node is connected via bridges, switches, or routers to at least one other node.","tags":["Networking"],"text":"A network where each node is connected via bridges, switches, or routers to at least one other node."},{"title":"MAN (metropolitan area network)","url":"https://sane-av.github.io/glossary/?search=metropolitan%20area%20network","type":"Glossary","snippet":"A communications network that covers a single geographic area, such as a suburb or city.","tags":["Networking"],"text":"A communications network that covers a single geographic area, such as a suburb or city."},{"title":"mic level","url":"https://sane-av.github.io/glossary/?search=mic%20level","type":"Glossary","snippet":"The very low-level signal from a microphone. Typically only a few millivolts.","tags":["Audio"],"text":"The very low-level signal from a microphone. Typically only a few millivolts."},{"title":"MEMS (microelectromechanical systems)","url":"https://sane-av.github.io/glossary/?search=microelectromechanical%20systems","type":"Glossary","snippet":"Mechanical devices built directly onto silicon chips using the same fabrication processes as microprocessors and memory systems. Best known as the digital micromirror devices (DMD) used for light switching in DLP projectors.","tags":["Video"],"text":"Mechanical devices built directly onto silicon chips using the same fabrication processes as microprocessors and memory systems. Best known as the digital micromirror devices (DMD) used for light switching in DLP projectors."},{"title":"microphone sensitivity","url":"https://sane-av.github.io/glossary/?search=microphone%20sensitivity","type":"Glossary","snippet":"A specification that indicates the electrical output of a microphone when it is subjected to a known sound pressure level. Usually measured in dBV/Pa.","tags":["Acoustics","Audio"],"text":"A specification that indicates the electrical output of a microphone when it is subjected to a known sound pressure level. Usually measured in dBV/Pa."},{"title":"middleware","url":"https://sane-av.github.io/glossary/?search=middleware","type":"Glossary","snippet":"Software that provides services to applications that aren’t available from the operating system. In a streaming system, for example, middleware may perform transcoding, compression, or remote access authentication.","tags":["Networking","Systems & Control","Security"],"text":"Software that provides services to applications that aren’t available from the operating system. In a streaming system, for example, middleware may perform transcoding, compression, or remote access authentication."},{"title":"midrange","url":"https://sane-av.github.io/glossary/?search=midrange","type":"Glossary","snippet":"A loudspeaker that reproduces midrange frequencies, typically 300Hz to 8kHz.","tags":["Audio"],"text":"A loudspeaker that reproduces midrange frequencies, typically 300Hz to 8kHz."},{"title":"milestone","url":"https://sane-av.github.io/glossary/?search=milestone","type":"Glossary","snippet":"A significant or key event in a project, usually the completion of a major deliverable or the occurrence of an important event. It can often be associated with payment milestones and client approvals.","tags":["Project Management"],"text":"A significant or key event in a project, usually the completion of a major deliverable or the occurrence of an important event. It can often be associated with payment milestones and client approvals."},{"title":"millwork","url":"https://sane-av.github.io/glossary/?search=millwork","type":"Glossary","snippet":"Carpentry work produced in a mill or factory. Usually refers to finished woodwork such as doors, molding, trim, flooring, cupboards, and wall paneling.","tags":["Cabling"],"text":"Carpentry work produced in a mill or factory. Usually refers to finished woodwork such as doors, molding, trim, flooring, cupboards, and wall paneling."},{"title":"mitigation","url":"https://sane-av.github.io/glossary/?search=mitigation","type":"Glossary","snippet":"The process of applying measures that diminish the likelihood of an undesirable occurrence or reduce the impact if it occurs.","tags":["General"],"text":"The process of applying measures that diminish the likelihood of an undesirable occurrence or reduce the impact if it occurs."},{"title":"mix-minus system","url":"https://sane-av.github.io/glossary/?search=mix-minus%20system","type":"Glossary","snippet":"An audio mix with some channels omitted. Also known as a clean feed mix. Used in speech reinforcement, interruptible foldback (IFB), and conferencing systems to allow multiple participants to be heard without echoes or feedback. Each participant is provided with a submix which includes all signals except the closest microphone.","tags":["Acoustics","Audio"],"text":"An audio mix with some channels omitted. Also known as a clean feed mix. Used in speech reinforcement, interruptible foldback (IFB), and conferencing systems to allow multiple participants to be heard without echoes or feedback. Each participant is provided with a submix which includes all signals except the closest microphone."},{"title":"mixer","url":"https://sane-av.github.io/glossary/?search=mixer","type":"Glossary","snippet":"A device for blending multiple signal sources.","tags":["Audio"],"text":"A device for blending multiple signal sources."},{"title":"MHL (Mobile High-Definition Link)","url":"https://sane-av.github.io/glossary/?search=Mobile%20High-Definition%20Link","type":"Glossary","snippet":"A standard audio/video interface for connecting mobile electronics to high-definition televisions and audio receivers. SuperMHL is capable of 36Gbps with HDR and WCG video up to 8K at 120fps.","tags":["Audio","Video"],"text":"A standard audio/video interface for connecting mobile electronics to high-definition televisions and audio receivers. SuperMHL is capable of 36Gbps with HDR and WCG video up to 8K at 120fps."},{"title":"modular connector","url":"https://sane-av.github.io/glossary/?search=modular%20connector","type":"Glossary","snippet":"A latching electrical connector with four, six, or eight pins. Common modular connectors are RJ11(6P6C) and RJ-45 (8P8C).","tags":["Cabling"],"text":"A latching electrical connector with four, six, or eight pins. Common modular connectors are RJ11(6P6C) and RJ-45 (8P8C)."},{"title":"modulator","url":"https://sane-av.github.io/glossary/?search=modulator","type":"Glossary","snippet":"A device that varies one or more properties of a carrier signal (frequency, amplitude, phase) with information from another signal.","tags":["Electrical"],"text":"A device that varies one or more properties of a carrier signal (frequency, amplitude, phase) with information from another signal."},{"title":"MOSFET","url":"https://sane-av.github.io/glossary/?search=MOSFET","type":"Glossary","snippet":"Metal oxide semiconductor field-effect transistor. A semiconductor device with an insulated gate capable of significantly changing its load current with a small change in gate voltage. The power MOSFET is used for controlling and switching large currents. Also known as an insulated-gate field-effect transistor (IGFET).","tags":["Electrical"],"text":"Metal oxide semiconductor field-effect transistor. A semiconductor device with an insulated gate capable of significantly changing its load current with a small change in gate voltage. The power MOSFET is used for controlling and switching large currents. Also known as an insulated-gate field-effect transistor (IGFET)."},{"title":"MPLS (Multi-Protocol Label Switching)","url":"https://sane-av.github.io/glossary/?search=Multi-Protocol%20Label%20Switching","type":"Glossary","snippet":"A networking protocol that allows any combination of Data Link-layer (layer 2) protocols to be transported over any type of Network layer (layer 3). MPLS routes data by examining each packet’s MPLS label without examining packet . Implementing MPLS improves interoperability and routing speed.","tags":["Networking"],"text":"A networking protocol that allows any combination of Data Link-layer (layer 2) protocols to be transported over any type of Network layer (layer 3). MPLS routes data by examining each packet’s MPLS label without examining packet . Implementing MPLS improves interoperability and routing speed."},{"title":"MLD (Multicast Listener Discovery)","url":"https://sane-av.github.io/glossary/?search=Multicast%20Listener%20Discovery","type":"Glossary","snippet":"The IPv6 group management protocol. Multicast is natively supported by IPv6; any IPv6 router will support MLD. MLDv1 performs roughly the same functions as IGMPv2, and MLDv2 supports roughly the same functions as IGMPv3.","tags":["Networking"],"text":"The IPv6 group management protocol. Multicast is natively supported by IPv6; any IPv6 router will support MLD. MLDv1 performs roughly the same functions as IGMPv2, and MLDv2 supports roughly the same functions as IGMPv3."},{"title":"multicast streaming","url":"https://sane-av.github.io/glossary/?search=multicast%20streaming","type":"Glossary","snippet":"A one-to-many transmission, meaning one server sends out a single stream that can then be accessed by multiple clients. In IPv4, the IP address range (224.0.0.0 to 239.255.255.255) is reserved for multicast transmissions. In IPv6, multicast addresses have the prefix ff00::/8.","tags":["Networking"],"text":"A one-to-many transmission, meaning one server sends out a single stream that can then be accessed by multiple clients. In IPv4, the IP address range (224.0.0.0 to 239.255.255.255) is reserved for multicast transmissions. In IPv6, multicast addresses have the prefix ff00::/8."},{"title":"multimeter","url":"https://sane-av.github.io/glossary/?search=multimeter","type":"Glossary","snippet":"A test instrument with multiple ranges for measuring current, voltage, and resistance. Many instruments also include a simple continuity test capability.","tags":["Electrical"],"text":"A test instrument with multiple ranges for measuring current, voltage, and resistance. Many instruments also include a simple continuity test capability."},{"title":"multiplexing","url":"https://sane-av.github.io/glossary/?search=multiplexing","type":"Glossary","snippet":"The sharing of a single communications channel for multiple signals.","tags":["General"],"text":"The sharing of a single communications channel for multiple signals."},{"title":"multipoint","url":"https://sane-av.github.io/glossary/?search=multipoint","type":"Glossary","snippet":"Also called continuous presence, videoconferencing that links many sites to a common gateway service, allowing all sites to see, hear, and interact at the same time. Multipoint requires a bridge or bridging service.","tags":["Video","Networking"],"text":"Also called continuous presence, videoconferencing that links many sites to a common gateway service, allowing all sites to see, hear, and interact at the same time. Multipoint requires a bridge or bridging service."},{"title":"Murphy’s law","url":"https://sane-av.github.io/glossary/?search=Murphy%E2%80%99s%20law","type":"Glossary","snippet":"Also known as Sod’s law. If anything can go wrong, it will go wrong. A reminder that no assumptions should ever be made about the cause of a fault in a system. If you saw the identical fault last week, it will almost certainly have an entirely different cause this week.","tags":["General"],"text":"Also known as Sod’s law. If anything can go wrong, it will go wrong. A reminder that no assumptions should ever be made about the cause of a fault in a system. If you saw the identical fault last week, it will almost certainly have an entirely different cause this week."},{"title":"native resolution","url":"https://sane-av.github.io/glossary/?search=native%20resolution","type":"Glossary","snippet":"The number of rows of horizontal and vertical pixels that form the picture. The native resolution describes the actual resolution of the imaging device and not the resolution of the delivery signal.","tags":["Video"],"text":"The number of rows of horizontal and vertical pixels that form the picture. The native resolution describes the actual resolution of the imaging device and not the resolution of the delivery signal."},{"title":"near-field","url":"https://sane-av.github.io/glossary/?search=near-field","type":"Glossary","snippet":"The zone close to the sound source that has not been colored by room reflections. This is also known as direct sound.","tags":["Systems & Control"],"text":"The zone close to the sound source that has not been colored by room reflections. This is also known as direct sound."},{"title":"NAG (needed acoustic gain)","url":"https://sane-av.github.io/glossary/?search=needed%20acoustic%20gain","type":"Glossary","snippet":"The gain the sound system requires to achieve an equivalent acoustic level at the farthest listener equal to the level at the Equivalent Acoustic Distance (EAD).","tags":["Acoustics","Audio"],"text":"The gain the sound system requires to achieve an equivalent acoustic level at the farthest listener equal to the level at the Equivalent Acoustic Distance (EAD)."},{"title":"needs analysis","url":"https://sane-av.github.io/glossary/?search=needs%20analysis","type":"Glossary","snippet":"A needs analysis identifies the activities that the end users need to perform, then develops the functional descriptions of the systems that support those needs.","tags":["Project Management"],"text":"A needs analysis identifies the activities that the end users need to perform, then develops the functional descriptions of the systems that support those needs."},{"title":"NAT (network address translation)","url":"https://sane-av.github.io/glossary/?search=network%20address%20translation","type":"Glossary","snippet":"Any method of altering IP address information in IP packet headers as the packet traverses a routing device. NAT is typically implemented as part of a firewall strategy. The most common form of NAT is port address translation (PAT).","tags":["Networking","Security"],"text":"Any method of altering IP address information in IP packet headers as the packet traverses a routing device. NAT is typically implemented as part of a firewall strategy. The most common form of NAT is port address translation (PAT)."},{"title":"network bridge","url":"https://sane-av.github.io/glossary/?search=network%20bridge","type":"Glossary","snippet":"A network device that connects between two networks. It may translate between different protocols on the bridged networks.","tags":["Networking"],"text":"A network device that connects between two networks. It may translate between different protocols on the bridged networks."},{"title":"NIC (network interface card)","url":"https://sane-av.github.io/glossary/?search=network%20interface%20card","type":"Glossary","snippet":"An interface that allows a device to be connected to a network.","tags":["Networking"],"text":"An interface that allows a device to be connected to a network."},{"title":"network segment","url":"https://sane-av.github.io/glossary/?search=network%20segment","type":"Glossary","snippet":"A network segment is any single section of a network that is physically separated from the rest of the network by a networking device such as a switch or router. A segment may contain one or more hosts.","tags":["Networking"],"text":"A network segment is any single section of a network that is physically separated from the rest of the network by a networking device such as a switch or router. A segment may contain one or more hosts."},{"title":"network switch","url":"https://sane-av.github.io/glossary/?search=network%20switch","type":"Glossary","snippet":"A networking device that connects multiple network segments by storing the data packets sent from the transmitting segment and forwarding them to the receiving segment. Hosts on the segments are identified by their MAC addresses.","tags":["Networking"],"text":"A networking device that connects multiple network segments by storing the data packets sent from the transmitting segment and forwarding them to the receiving segment. Hosts on the segments are identified by their MAC addresses."},{"title":"network topology","url":"https://sane-av.github.io/glossary/?search=network%20topology","type":"Glossary","snippet":"The physical arrangement of the elements connected to a network.","tags":["Networking"],"text":"The physical arrangement of the elements connected to a network."},{"title":"neutral conductor","url":"https://sane-av.github.io/glossary/?search=neutral%20conductor","type":"Glossary","snippet":"The conductor in an electrical supply system that is connected to the earth/ground for current return. This is not part of the protective earth/grounding system. See also grounded conductor (for U.S. usage).","tags":["Electrical"],"text":"The conductor in an electrical supply system that is connected to the earth/ground for current return. This is not part of the protective earth/grounding system. See also grounded conductor (for U.S. usage)."},{"title":"nibble/nybble","url":"https://sane-av.github.io/glossary/?search=nibble%2Fnybble","type":"Glossary","snippet":"A group of 4 bits. Half a byte or half an octet. Usually written as a single hexadecimal digit (values 0 to f).","tags":["Networking"],"text":"A group of 4 bits. Half a byte or half an octet. Usually written as a single hexadecimal digit (values 0 to f)."},{"title":"nine-pin connector (DB-9)","url":"https://sane-av.github.io/glossary/?search=nine-pin%20connector%20(DB-9)","type":"Glossary","snippet":"The DB-9 is the most common type of connector used in RS-232 control systems.","tags":["Cabling","Signal Processing"],"text":"The DB-9 is the most common type of connector used in RS-232 control systems."},{"title":"nit","url":"https://sane-av.github.io/glossary/?search=nit","type":"Glossary","snippet":"The nonstandard, and now-deprecated, name for the candela per square meter (cd/m2), the unit of luminance. Formerly used to describe screen or surface brightness.","tags":["Video","Lighting"],"text":"The nonstandard, and now-deprecated, name for the candela per square meter (cd/m2), the unit of luminance. Formerly used to describe screen or surface brightness."},{"title":"noise","url":"https://sane-av.github.io/glossary/?search=noise","type":"Glossary","snippet":"Any signal present in a system other than the desired signal.","tags":["General"],"text":"Any signal present in a system other than the desired signal."},{"title":"NC (noise criterion)","url":"https://sane-av.github.io/glossary/?search=noise%20criterion","type":"Glossary","snippet":"A rating system used primarily in the United States to establish satisfactory conditions for speech intelligibility and general living environments. Measurements are taken at eight center octave frequencies from 63Hz to 8kHz and plotted against a standardized curve. Very similar to the noise rating (NR) system. Also abbreviated NC.","tags":["Acoustics"],"text":"A rating system used primarily in the United States to establish satisfactory conditions for speech intelligibility and general living environments. Measurements are taken at eight center octave frequencies from 63Hz to 8kHz and plotted against a standardized curve. Very similar to the noise rating (NR) system. Also abbreviated NC."},{"title":"NR (noise rating)","url":"https://sane-av.github.io/glossary/?search=noise%20rating","type":"Glossary","snippet":"A rating system developed to establish satisfactory conditions for speech intelligibility and general living environments. Measurements are taken at eight center octave frequencies from 63Hz to 8kHz and plotted against a standardized curve. Very similar to the noise criterion (NC) rating system used in the United States.","tags":["Acoustics"],"text":"A rating system developed to establish satisfactory conditions for speech intelligibility and general living environments. Measurements are taken at eight center octave frequencies from 63Hz to 8kHz and plotted against a standardized curve. Very similar to the noise criterion (NC) rating system used in the United States."},{"title":"noise-masking system","url":"https://sane-av.github.io/glossary/?search=noise-masking%20system","type":"Glossary","snippet":"Also known as a sound-masking or speech privacy system. A sound system that deliberately introduces background noise into a space to raise the threshold of hearing and thus increase privacy between occupants in a shared space.","tags":["Acoustics","Electrical"],"text":"Also known as a sound-masking or speech privacy system. A sound system that deliberately introduces background noise into a space to raise the threshold of hearing and thus increase privacy between occupants in a shared space."},{"title":"noisy ground","url":"https://sane-av.github.io/glossary/?search=noisy%20ground","type":"Glossary","snippet":"An electrical connection to a ground point that produces or injects spurious voltages into a system through the connection to ground (IEEE Std. 142-1991).","tags":["Electrical","Standards"],"text":"An electrical connection to a ground point that produces or injects spurious voltages into a system through the connection to ground (IEEE Std. 142-1991)."},{"title":"nominal impedance","url":"https://sane-av.github.io/glossary/?search=nominal%20impedance","type":"Glossary","snippet":"An approximation of the typical impedance of a device or system.","tags":["Electrical"],"text":"An approximation of the typical impedance of a device or system."},{"title":"nonvolatile memory","url":"https://sane-av.github.io/glossary/?search=nonvolatile%20memory","type":"Glossary","snippet":"Computer memory that retains its data when not powered up. Includes flash memory; read-only memory (ROM); erasable programmable ROM (EPROM); electrically erasable programmable ROM (EEPROM); optical disks; and magnetic storage such as floppy disks, hard disks, and magnetic tape.","tags":["Cabling"],"text":"Computer memory that retains its data when not powered up. Includes flash memory; read-only memory (ROM); erasable programmable ROM (EPROM); electrically erasable programmable ROM (EEPROM); optical disks; and magnetic storage such as floppy disks, hard disks, and magnetic tape."},{"title":"notch filter","url":"https://sane-av.github.io/glossary/?search=notch%20filter","type":"Glossary","snippet":"A filter that notches out, or eliminates, a specific band of frequencies.","tags":["Signal Processing"],"text":"A filter that notches out, or eliminates, a specific band of frequencies."},{"title":"NOM (number of open microphones)","url":"https://sane-av.github.io/glossary/?search=number%20of%20open%20microphones","type":"Glossary","snippet":"A measure that takes into account the increased possibility of feedback by adding more live microphones in a space. Each time the number of open microphones is doubled, you lose 3dB of gain before feedback.","tags":["Audio"],"text":"A measure that takes into account the increased possibility of feedback by adding more live microphones in a space. Each time the number of open microphones is doubled, you lose 3dB of gain before feedback."},{"title":"Nyquist-Shannon sampling theorem","url":"https://sane-av.github.io/glossary/?search=Nyquist-Shannon%20sampling%20theorem","type":"Glossary","snippet":"States that an analog signal can be reconstructed if it is encoded using a sampling rate that is greater than twice the highest frequency sampled. For example, since the range of human hearing extends to 20kHz, the minimum sampling rate for digital audio should be greater than 40kHz. The higher the sampling rate above this minimum, the more accurate the digital sample.","tags":["Audio","Signal Processing","Standards"],"text":"States that an analog signal can be reconstructed if it is encoded using a sampling rate that is greater than twice the highest frequency sampled. For example, since the range of human hearing extends to 20kHz, the minimum sampling rate for digital audio should be greater than 40kHz. The higher the sampling rate above this minimum, the more accurate the digital sample."},{"title":"octave","url":"https://sane-av.github.io/glossary/?search=octave","type":"Glossary","snippet":"A band, or group, of frequencies in which the highest frequency in the band is double the lowest frequency. For example, 200Hz to 400Hz is an octave, 6kHz to 12kHz is an octave, and so on.","tags":["General"],"text":"A band, or group, of frequencies in which the highest frequency in the band is double the lowest frequency. For example, 200Hz to 400Hz is an octave, 6kHz to 12kHz is an octave, and so on."},{"title":"octet","url":"https://sane-av.github.io/glossary/?search=octet","type":"Glossary","snippet":"A group of eight binary digits (bits), often called a byte.","tags":["General"],"text":"A group of eight binary digits (bits), often called a byte."},{"title":"Ohm’s law","url":"https://sane-av.github.io/glossary/?search=Ohm%E2%80%99s%20law","type":"Glossary","snippet":"A law that defines the relationship between current, voltage, and resistance in an electrical circuit. The current is proportional to the applied voltage and inversely proportional to the resistance, giving the formula I = V ÷ R, where I is the current (in amps), V is the voltage (in volts), and R is the resistance (in ohms).","tags":["Electrical","Standards"],"text":"A law that defines the relationship between current, voltage, and resistance in an electrical circuit. The current is proportional to the applied voltage and inversely proportional to the resistance, giving the formula I = V ÷ R, where I is the current (in amps), V is the voltage (in volts), and R is the resistance (in ohms)."},{"title":"omnidirectional","url":"https://sane-av.github.io/glossary/?search=omnidirectional","type":"Glossary","snippet":"Receiving signals from or transmitting in all directions. Used to describe the sensitivity or radiation pattern for devices that operate equally in nearly all directions.","tags":["Audio"],"text":"Receiving signals from or transmitting in all directions. Used to describe the sensitivity or radiation pattern for devices that operate equally in nearly all directions."},{"title":"on-axis","url":"https://sane-av.github.io/glossary/?search=on-axis","type":"Glossary","snippet":"Along the axis of a symmetrical pattern. In projection, the center line of a screen, perpendicular to the viewing area for a displayed image. In audio, along the central axis of a microphone’s pick-up pattern or along the central axis of a loudspeaker’s dispersion pattern.","tags":["Audio","Video","Lighting"],"text":"Along the axis of a symmetrical pattern. In projection, the center line of a screen, perpendicular to the viewing area for a displayed image. In audio, along the central axis of a microphone’s pick-up pattern or along the central axis of a loudspeaker’s dispersion pattern."},{"title":"open port","url":"https://sane-av.github.io/glossary/?search=open%20port","type":"Glossary","snippet":"A sub-address in Transmission Control Protocol or User Datagram Protocol that is configured to accept packets of data in network traffic.","tags":["Networking"],"text":"A sub-address in Transmission Control Protocol or User Datagram Protocol that is configured to accept packets of data in network traffic."},{"title":"OLED (organic light-emitting diode)","url":"https://sane-av.github.io/glossary/?search=organic%20light-emitting%20diode","type":"Glossary","snippet":"A semiconductor light-emitting diode constructed from organic compounds. Displays built from OLEDs generally use separate layers for emitting the red, green, and blue components of an image.","tags":["Video","Electrical"],"text":"A semiconductor light-emitting diode constructed from organic compounds. Displays built from OLEDs generally use separate layers for emitting the red, green, and blue components of an image."},{"title":"oscilloscope","url":"https://sane-av.github.io/glossary/?search=oscilloscope","type":"Glossary","snippet":"A device that allows the viewing and measurement of electronic signals on a visual display.","tags":["Video"],"text":"A device that allows the viewing and measurement of electronic signals on a visual display."},{"title":"OSI Model","url":"https://sane-av.github.io/glossary/?search=OSI%20Model","type":"Glossary","snippet":"Open Systems Interconnection Model. This is a reference model developed by ISO in 1984 as a conceptual framework of standards for communication in the data network across different equipment and applications by different vendors. Under this model network communication protocols are divided into seven categories, or layers.","tags":["Networking","Standards"],"text":"Open Systems Interconnection Model. This is a reference model developed by ISO in 1984 as a conceptual framework of standards for communication in the data network across different equipment and applications by different vendors. Under this model network communication protocols are divided into seven categories, or layers."},{"title":"overcurrent","url":"https://sane-av.github.io/glossary/?search=overcurrent","type":"Glossary","snippet":"Any current in excess of the rated current for equipment or a conductor. It may result from overload, a short circuit, or a ground fault.","tags":["Electrical"],"text":"Any current in excess of the rated current for equipment or a conductor. It may result from overload, a short circuit, or a ground fault."},{"title":"overcurrent protection device","url":"https://sane-av.github.io/glossary/?search=overcurrent%20protection%20device","type":"Glossary","snippet":"A safety device designed to disconnect a circuit if the current exceeds a predetermined value. Examples are circuit breakers and fuses.","tags":["Electrical"],"text":"A safety device designed to disconnect a circuit if the current exceeds a predetermined value. Examples are circuit breakers and fuses."},{"title":"packet filtering","url":"https://sane-av.github.io/glossary/?search=packet%20filtering","type":"Glossary","snippet":"A network data filtering process that uses rules to determine whether a data packet will be allowed to pass through a router or gateway. The filtering rules are based on the of each packet.","tags":["Networking","Signal Processing"],"text":"A network data filtering process that uses rules to determine whether a data packet will be allowed to pass through a router or gateway. The filtering rules are based on the of each packet."},{"title":"panelboard","url":"https://sane-av.github.io/glossary/?search=panelboard","type":"Glossary","snippet":"Another name for an electrical load-distribution board.","tags":["Electrical"],"text":"Another name for an electrical load-distribution board."},{"title":"parallel circuit","url":"https://sane-av.github.io/glossary/?search=parallel%20circuit","type":"Glossary","snippet":"A circuit in which the voltage is the same across each load, but the current divides and takes all the available paths and returns to the source.","tags":["Electrical"],"text":"A circuit in which the voltage is the same across each load, but the current divides and takes all the available paths and returns to the source."},{"title":"parametric equalizer","url":"https://sane-av.github.io/glossary/?search=parametric%20equalizer","type":"Glossary","snippet":"An equalizer that allows discrete selection of a center frequency and adjustment of the width of the frequency range that will be affected. This can allow for precise manipulation with minimal impact of adjacent frequencies.","tags":["Audio","Signal Processing"],"text":"An equalizer that allows discrete selection of a center frequency and adjustment of the width of the frequency range that will be affected. This can allow for precise manipulation with minimal impact of adjacent frequencies."},{"title":"password","url":"https://sane-av.github.io/glossary/?search=password","type":"Glossary","snippet":"A technique used to authenticate the identity of a user by requiring the input of a predetermined set of characters, such as letters, numbers, or other symbols.","tags":["Security"],"text":"A technique used to authenticate the identity of a user by requiring the input of a predetermined set of characters, such as letters, numbers, or other symbols."},{"title":"peak","url":"https://sane-av.github.io/glossary/?search=peak","type":"Glossary","snippet":"The highest level of signal amplitude, determined by the height of the signal’s waveform.","tags":["General"],"text":"The highest level of signal amplitude, determined by the height of the signal’s waveform."},{"title":"peaking","url":"https://sane-av.github.io/glossary/?search=peaking","type":"Glossary","snippet":"An adjustment method that allows compensation for high-frequency loss in cables.","tags":["Cabling","Signal Processing"],"text":"An adjustment method that allows compensation for high-frequency loss in cables."},{"title":"peaking control","url":"https://sane-av.github.io/glossary/?search=peaking%20control","type":"Glossary","snippet":"Electronic adjustments within a video component that can be used to compensate for system losses.","tags":["Video","Signal Processing"],"text":"Electronic adjustments within a video component that can be used to compensate for system losses."},{"title":"penetration testing","url":"https://sane-av.github.io/glossary/?search=penetration%20testing","type":"Glossary","snippet":"A method of assessing the security posture of an organization’s security systems by searching for vulnerabilities that an attacker could exploit.","tags":["Security"],"text":"A method of assessing the security posture of an organization’s security systems by searching for vulnerabilities that an attacker could exploit."},{"title":"permissible area","url":"https://sane-av.github.io/glossary/?search=permissible%20area","type":"Glossary","snippet":"The maximum amount of space that cables should occupy inside an electrical conduit.","tags":["Cabling"],"text":"The maximum amount of space that cables should occupy inside an electrical conduit."},{"title":"PAN (personal area network)","url":"https://sane-av.github.io/glossary/?search=personal%20area%20network","type":"Glossary","snippet":"A limited-range, usually wireless, network that serves a single person or small workgroup.","tags":["Networking"],"text":"A limited-range, usually wireless, network that serves a single person or small workgroup."},{"title":"phantom power","url":"https://sane-av.github.io/glossary/?search=phantom%20power","type":"Glossary","snippet":"A DC power supply delivered as an “invisible” overlay on the signal wires of a system. In audio phantom power systems, a voltage is overlaid on microphone signal lines to enable the remote powering of devices such as condenser microphones and active direct input boxes. In power over Ethernet (PoE) systems, the voltage is overlaid across both wires in a twisted-pair.","tags":["Audio","Networking","Electrical","Cabling"],"text":"A DC power supply delivered as an “invisible” overlay on the signal wires of a system. In audio phantom power systems, a voltage is overlaid on microphone signal lines to enable the remote powering of devices such as condenser microphones and active direct input boxes. In power over Ethernet (PoE) systems, the voltage is overlaid across both wires in a twisted-pair."},{"title":"phase","url":"https://sane-av.github.io/glossary/?search=phase","type":"Glossary","snippet":"A particular value of time for any periodic function. For a point on a sine wave, it is a measure of that point’s distance from the most recent positive-going zero crossing of the waveform. It is measured in degrees; 0 to 360 degrees is a complete cycle.","tags":["Electrical"],"text":"A particular value of time for any periodic function. For a point on a sine wave, it is a measure of that point’s distance from the most recent positive-going zero crossing of the waveform. It is measured in degrees; 0 to 360 degrees is a complete cycle."},{"title":"phase-control dimming","url":"https://sane-av.github.io/glossary/?search=phase-control%20dimming","type":"Glossary","snippet":"A method of electronic dimming that progressively removes the leading edge of each half-cycle of the AC power to a lamp.","tags":["Electrical","Lighting"],"text":"A method of electronic dimming that progressively removes the leading edge of each half-cycle of the AC power to a lamp."},{"title":"phishing","url":"https://sane-av.github.io/glossary/?search=phishing","type":"Glossary","snippet":"The fraudulent practice of sending messages purporting to be from a known or reputable sender in order to induce individuals to reveal confidential information.","tags":["Security"],"text":"The fraudulent practice of sending messages purporting to be from a known or reputable sender in order to induce individuals to reveal confidential information."},{"title":"phono connector","url":"https://sane-av.github.io/glossary/?search=phono%20connector","type":"Glossary","snippet":"The international name for the type of coaxial connector known as RCA in North America.","tags":["Cabling"],"text":"The international name for the type of coaxial connector known as RCA in North America."},{"title":"phosphor","url":"https://sane-av.github.io/glossary/?search=phosphor","type":"Glossary","snippet":"A substance that produces light when stimulated by radiation. Phosphors are used to produce some colors of visible light in fluorescent lamps, LED sources, some laser light sources, and CRT and plasma displays.","tags":["Video","Lighting"],"text":"A substance that produces light when stimulated by radiation. Phosphors are used to produce some colors of visible light in fluorescent lamps, LED sources, some laser light sources, and CRT and plasma displays."},{"title":"physical security","url":"https://sane-av.github.io/glossary/?search=physical%20security","type":"Glossary","snippet":"The practice of protecting AV and information systems from material threats such as actions and events that could damage them or compromise their data.","tags":["Security"],"text":"The practice of protecting AV and information systems from material threats such as actions and events that could damage them or compromise their data."},{"title":"ping","url":"https://sane-av.github.io/glossary/?search=ping","type":"Glossary","snippet":"A computer network software utility that measures the round-trip time of test messages between hosts on a computer network. Implemented on IP networks using the Internet Control Message Protocol (ICMP). The name derives from the use of sonic “pings” in sonar for underwater ranging.","tags":["General"],"text":"A computer network software utility that measures the round-trip time of test messages between hosts on a computer network. Implemented on IP networks using the Internet Control Message Protocol (ICMP). The name derives from the use of sonic “pings” in sonar for underwater ranging."},{"title":"pink noise","url":"https://sane-av.github.io/glossary/?search=pink%20noise","type":"Glossary","snippet":"A signal with a broad spectrum of random frequencies that has equal energy in each octave band.","tags":["Audio"],"text":"A signal with a broad spectrum of random frequencies that has equal energy in each octave band."},{"title":"PNG (pink noise generator)","url":"https://sane-av.github.io/glossary/?search=pink%20noise%20generator","type":"Glossary","snippet":"A device to generate pink noise. An audio PNG is commonly used in conjunction with an audio spectrum analyzer to evaluate and align a sound system in an environment.","tags":["Audio"],"text":"A device to generate pink noise. An audio PNG is commonly used in conjunction with an audio spectrum analyzer to evaluate and align a sound system in an environment."},{"title":"pixel","url":"https://sane-av.github.io/glossary/?search=pixel","type":"Glossary","snippet":"A contraction of the words picture and element. The smallest element used to build an image.","tags":["Video"],"text":"A contraction of the words picture and element. The smallest element used to build an image."},{"title":"plan view","url":"https://sane-av.github.io/glossary/?search=plan%20view","type":"Glossary","snippet":"A drawing of a space from the “top view” taken directly from above. Examples include a floor plan and site plan.","tags":["Project Management"],"text":"A drawing of a space from the “top view” taken directly from above. Examples include a floor plan and site plan."},{"title":"plane of screen","url":"https://sane-av.github.io/glossary/?search=plane%20of%20screen","type":"Glossary","snippet":"Identification of image position on a plan or drawing relative to other plotted locations. It is a notional plane whether in plan view or elevation, that aligns with the front surface of the screen (that is, image position) used as a datum to define viewers’ relative positions.","tags":["Video","Project Management"],"text":"Identification of image position on a plan or drawing relative to other plotted locations. It is a notional plane whether in plan view or elevation, that aligns with the front surface of the screen (that is, image position) used as a datum to define viewers’ relative positions."},{"title":"PDP (plasma display panel)","url":"https://sane-av.github.io/glossary/?search=plasma%20display%20panel","type":"Glossary","snippet":"A direct-view display technology consisting of an array of pixels, which are composed of three subpixels, corresponding to the colors red, green, and blue. Gas in the plasma state is used to react with phosphors in each subpixel to produce colored light (red, green, or blue) from a phosphor in each subpixel.","tags":["Video","Lighting"],"text":"A direct-view display technology consisting of an array of pixels, which are composed of three subpixels, corresponding to the colors red, green, and blue. Gas in the plasma state is used to react with phosphors in each subpixel to produce colored light (red, green, or blue) from a phosphor in each subpixel."},{"title":"playback system","url":"https://sane-av.github.io/glossary/?search=playback%20system","type":"Glossary","snippet":"A system designed specifically to replay recorded material.","tags":["Audio"],"text":"A system designed specifically to replay recorded material."},{"title":"plenum space","url":"https://sane-av.github.io/glossary/?search=plenum%20space","type":"Glossary","snippet":"The plenum space is also called environmental air space. It is an area connected to air ducts that forms part of the air distribution system.","tags":["Cabling"],"text":"The plenum space is also called environmental air space. It is an area connected to air ducts that forms part of the air distribution system."},{"title":"PoDL","url":"https://sane-av.github.io/glossary/?search=PoDL","type":"Glossary","snippet":"Power over data line. See Power over Ethernet.","tags":["Networking"],"text":"Power over data line. See Power over Ethernet."},{"title":"PoE","url":"https://sane-av.github.io/glossary/?search=PoE","type":"Glossary","snippet":"DC power supply delivered as an \"invisible\" overlay on the data lines of an Ethernet network system. The voltage is overlaid in common mode across both wires in a twisted-pair to eliminate any effect on the data. Also known as power over data line (PoDL). PoE is used to power a wide range of Ethernet-connected devices. Abbreviation for power over Ethernet.","tags":["Networking"],"text":"DC power supply delivered as an \"invisible\" overlay on the data lines of an Ethernet network system. The voltage is overlaid in common mode across both wires in a twisted-pair to eliminate any effect on the data. Also known as power over data line (PoDL). PoE is used to power a wide range of Ethernet-connected devices. Abbreviation for power over Ethernet."},{"title":"point source","url":"https://sane-av.github.io/glossary/?search=point%20source","type":"Glossary","snippet":"A sound system that has an apparent central location for the loudspeakers. This type of sound system is typically used in a performance venue or a large house of worship.","tags":["Audio"],"text":"A sound system that has an apparent central location for the loudspeakers. This type of sound system is typically used in a performance venue or a large house of worship."},{"title":"point-to-point","url":"https://sane-av.github.io/glossary/?search=point-to-point","type":"Glossary","snippet":"Conferencing where sites are directly linked.","tags":["General"],"text":"Conferencing where sites are directly linked."},{"title":"polar pattern","url":"https://sane-av.github.io/glossary/?search=polar%20pattern","type":"Glossary","snippet":"Also known as pickup pattern or transmission pattern. The shape of the pattern covered by the pickup or transmission device.","tags":["Audio"],"text":"Also known as pickup pattern or transmission pattern. The shape of the pattern covered by the pickup or transmission device."},{"title":"polar plot","url":"https://sane-av.github.io/glossary/?search=polar%20plot","type":"Glossary","snippet":"A polar plot is a graphical representation of the relationship between a device’s directionality and its input or output.","tags":["General"],"text":"A polar plot is a graphical representation of the relationship between a device’s directionality and its input or output."},{"title":"port","url":"https://sane-av.github.io/glossary/?search=port","type":"Glossary","snippet":"1. An input and/or output socket on an electronic device. 2. In a TCP/IP network, a 16-bit number included in the TCP or UDP Transport-layer (layer 4) header. The port number typically indicates the Application-layer (layer 7) protocol that generated a data packet. A port may also be called by its associated service (e.g., port 80 may be called HTTP, or port 23 may be called Telnet). 3. To relocate an application or function to a new platform.","tags":["Networking"],"text":"1. An input and/or output socket on an electronic device. 2. In a TCP/IP network, a 16-bit number included in the TCP or UDP Transport-layer (layer 4) header. The port number typically indicates the Application-layer (layer 7) protocol that generated a data packet. A port may also be called by its associated service (e.g., port 80 may be called HTTP, or port 23 may be called Telnet). 3. To relocate an application or function to a new platform."},{"title":"PAT (port address translation)","url":"https://sane-av.github.io/glossary/?search=port%20address%20translation","type":"Glossary","snippet":"A method of network address translation (NAT) whereby devices with private, unregistered IP addresses can access the Internet through a device with a registered IP address. Unregistered clients send datagrams to a NAT server with a globally routable address (typically a firewall, a gateway, or a router). The NAT server forwards the data to its destination and relays responses to the original client.","tags":["Networking","Security"],"text":"A method of network address translation (NAT) whereby devices with private, unregistered IP addresses can access the Internet through a device with a registered IP address. Unregistered clients send datagrams to a NAT server with a globally routable address (typically a firewall, a gateway, or a router). The NAT server forwards the data to its destination and relays responses to the original client."},{"title":"post tension type construction","url":"https://sane-av.github.io/glossary/?search=post%20tension%20type%20construction","type":"Glossary","snippet":"A type of structure that uses metal cables embedded within a concrete slab to support a structure. The cables act as a suspension support system that allows for wider spacing of support structures within a building.","tags":["Cabling"],"text":"A type of structure that uses metal cables embedded within a concrete slab to support a structure. The cables act as a suspension support system that allows for wider spacing of support structures within a building."},{"title":"PAG (potential acoustic gain)","url":"https://sane-av.github.io/glossary/?search=potential%20acoustic%20gain","type":"Glossary","snippet":"The potential gain that can be delivered by the sound system without ringing and before feedback occurs. It is based upon the number of open microphones and the distances between sources (like a presenter) and microphones, microphones and loudspeakers, and listeners and loudspeakers.","tags":["Acoustics","Audio"],"text":"The potential gain that can be delivered by the sound system without ringing and before feedback occurs. It is based upon the number of open microphones and the distances between sources (like a presenter) and microphones, microphones and loudspeakers, and listeners and loudspeakers."},{"title":"power","url":"https://sane-av.github.io/glossary/?search=power","type":"Glossary","snippet":"The rate at which work is done. Measured in watts (W); 1 watt = 1 joule/second. The symbol for power is P.","tags":["Electrical"],"text":"The rate at which work is done. Measured in watts (W); 1 watt = 1 joule/second. The symbol for power is P."},{"title":"power amplifier","url":"https://sane-av.github.io/glossary/?search=power%20amplifier","type":"Glossary","snippet":"Amplifies an audio signal to a level sufficient to drive loudspeakers.","tags":["Audio"],"text":"Amplifies an audio signal to a level sufficient to drive loudspeakers."},{"title":"power conditioner","url":"https://sane-av.github.io/glossary/?search=power%20conditioner","type":"Glossary","snippet":"Also known as a line conditioner or power line conditioner. A device that conditions the quality of power being fed to equipment by regulating the voltage and eliminating line noise.","tags":["Electrical"],"text":"Also known as a line conditioner or power line conditioner. A device that conditions the quality of power being fed to equipment by regulating the voltage and eliminating line noise."},{"title":"PDU (power distribution unit)","url":"https://sane-av.github.io/glossary/?search=power%20distribution%20unit","type":"Glossary","snippet":"An electrical device that distributes mains power to multiple electrical devices. A PDU may contain switches, overcurrent protection, voltage and/or current monitoring, remote circuit-controllers, and power receptacles. See also power strip.","tags":["Electrical"],"text":"An electrical device that distributes mains power to multiple electrical devices. A PDU may contain switches, overcurrent protection, voltage and/or current monitoring, remote circuit-controllers, and power receptacles. See also power strip."},{"title":"power over Ethernet","url":"https://sane-av.github.io/glossary/?search=power%20over%20Ethernet","type":"Glossary","snippet":"Also known as power over data line (PoDL), PoE is DC power supply delivered as an “invisible” overlay on the data lines of an Ethernet network system. The voltage is overlaid in common mode across both wires in a twisted-pair to eliminate any effect on the data. PoE is used to power a wide range of Ethernet-connected devices.","tags":["Networking","Electrical","Cabling","Signal Processing"],"text":"Also known as power over data line (PoDL), PoE is DC power supply delivered as an “invisible” overlay on the data lines of an Ethernet network system. The voltage is overlaid in common mode across both wires in a twisted-pair to eliminate any effect on the data. PoE is used to power a wide range of Ethernet-connected devices."},{"title":"power sequencing","url":"https://sane-av.github.io/glossary/?search=power%20sequencing","type":"Glossary","snippet":"The act of powering on and off equipment that requires a progressive startup or shutdown sequence for safe or convenient operations. Sequencing may help prevent tripping circuit breakers by limiting surge or inrush currents when devices are powered up.","tags":["Electrical"],"text":"The act of powering on and off equipment that requires a progressive startup or shutdown sequence for safe or convenient operations. Sequencing may help prevent tripping circuit breakers by limiting surge or inrush currents when devices are powered up."},{"title":"power sourcing equipment","url":"https://sane-av.github.io/glossary/?search=power%20sourcing%20equipment","type":"Glossary","snippet":"Power sourcing equipment (PSE) are devices that provide power into a PoE system.","tags":["Networking"],"text":"Power sourcing equipment (PSE) are devices that provide power into a PoE system."},{"title":"power strip","url":"https://sane-av.github.io/glossary/?search=power%20strip","type":"Glossary","snippet":"A block of electrical outlets attached to a power lead, designed to enable multiple devices to be powered from a single electrical outlet. Power strips may incorporate power indicators, individual switches, overload protection, and surge protection.","tags":["Electrical"],"text":"A block of electrical outlets attached to a power lead, designed to enable multiple devices to be powered from a single electrical outlet. Power strips may incorporate power indicators, individual switches, overload protection, and surge protection."},{"title":"powered device","url":"https://sane-av.github.io/glossary/?search=powered%20device","type":"Glossary","snippet":"A powered device (PD) is a device powered by PoE.","tags":["Networking"],"text":"A powered device (PD) is a device powered by PoE."},{"title":"preamplifier","url":"https://sane-av.github.io/glossary/?search=preamplifier","type":"Glossary","snippet":"An amplifier that boosts a low-level electronic signal before it is sent to other processing equipment.","tags":["Audio"],"text":"An amplifier that boosts a low-level electronic signal before it is sent to other processing equipment."},{"title":"preset","url":"https://sane-av.github.io/glossary/?search=preset","type":"Glossary","snippet":"1. A recallable state of settings and/or levels. 2. In lighting, a recallable state of lighting levels for one or more zones.","tags":["Systems & Control"],"text":"1. A recallable state of settings and/or levels. 2. In lighting, a recallable state of lighting levels for one or more zones."},{"title":"PZM (pressure zone microphone)","url":"https://sane-av.github.io/glossary/?search=pressure%20zone%20microphone","type":"Glossary","snippet":"An alternative name for a boundary microphone.","tags":["Audio","Systems & Control"],"text":"An alternative name for a boundary microphone."},{"title":"primary optic","url":"https://sane-av.github.io/glossary/?search=primary%20optic","type":"Glossary","snippet":"Also known as the primary lens. The major lens in an optical system. In a projector, the primary lens usually controls the focus of the image on a screen.","tags":["Video","Cabling"],"text":"Also known as the primary lens. The major lens in an optical system. In a projector, the primary lens usually controls the focus of the image on a screen."},{"title":"program report","url":"https://sane-av.github.io/glossary/?search=program%20report","type":"Glossary","snippet":"A document that describes the client’s specific needs, the system purpose and functionality, and the designer’s best estimate of probable cost in a nontechnical format for review and approval by the owner. Also known as the AV narrative, the discovery phase report, the return brief, or the concept design report.","tags":["Electrical","Project Management"],"text":"A document that describes the client’s specific needs, the system purpose and functionality, and the designer’s best estimate of probable cost in a nontechnical format for review and approval by the owner. Also known as the AV narrative, the discovery phase report, the return brief, or the concept design report."},{"title":"progressive scanning","url":"https://sane-av.github.io/glossary/?search=progressive%20scanning","type":"Glossary","snippet":"Scanning that traces the image’s scan lines sequentially.","tags":["Video"],"text":"Scanning that traces the image’s scan lines sequentially."},{"title":"PIM (Protocol Independent Multicast)","url":"https://sane-av.github.io/glossary/?search=Protocol%20Independent%20Multicast","type":"Glossary","snippet":"Allows multicast routing over LANs, WANs, or the open Internet. Rather than routing information on their own, PIM protocols use the routing information supplied by whatever routing protocol the network is already using.","tags":["Networking"],"text":"Allows multicast routing over LANs, WANs, or the open Internet. Rather than routing information on their own, PIM protocols use the routing information supplied by whatever routing protocol the network is already using."},{"title":"pulling tension","url":"https://sane-av.github.io/glossary/?search=pulling%20tension","type":"Glossary","snippet":"The maximum amount of tension that can be applied to a cable or conductor before it is damaged.","tags":["Electrical","Cabling"],"text":"The maximum amount of tension that can be applied to a cable or conductor before it is damaged."},{"title":"pure tone","url":"https://sane-av.github.io/glossary/?search=pure%20tone","type":"Glossary","snippet":"The lowest frequency in a harmonic series. A single-frequency sound with no harmonics or overtones. Also known as fundamental frequency.","tags":["General"],"text":"The lowest frequency in a harmonic series. A single-frequency sound with no harmonics or overtones. Also known as fundamental frequency."},{"title":"Q factor","url":"https://sane-av.github.io/glossary/?search=Q%20factor","type":"Glossary","snippet":"The quality factor of an audio filter is the ratio of the height of the center frequency of the filter to the bandwidth of the filter at the 3dB point.","tags":["Audio","Signal Processing"],"text":"The quality factor of an audio filter is the ratio of the height of the center frequency of the filter to the bandwidth of the filter at the 3dB point."},{"title":"quality of service","url":"https://sane-av.github.io/glossary/?search=quality%20of%20service","type":"Glossary","snippet":"Any method of managing network data traffic to preserve system functionality and provide the required bandwidth for critical applications. Typically, QoS involves some combination of bandwidth allocation and data prioritization.","tags":["Networking"],"text":"Any method of managing network data traffic to preserve system functionality and provide the required bandwidth for critical applications. Typically, QoS involves some combination of bandwidth allocation and data prioritization."},{"title":"quiet ground","url":"https://sane-av.github.io/glossary/?search=quiet%20ground","type":"Glossary","snippet":"A point on a ground system that does not inject spurious voltages into the electronic system. There are no standards to measure how quiet a quiet ground is.","tags":["Electrical"],"text":"A point on a ground system that does not inject spurious voltages into the electronic system. There are no standards to measure how quiet a quiet ground is."},{"title":"raceway","url":"https://sane-av.github.io/glossary/?search=raceway","type":"Glossary","snippet":"An enclosed channel of metal or nonmetallic materials designed for carrying wires, cables, or busbars.","tags":["Electrical","Cabling"],"text":"An enclosed channel of metal or nonmetallic materials designed for carrying wires, cables, or busbars."},{"title":"rack","url":"https://sane-av.github.io/glossary/?search=rack","type":"Glossary","snippet":"An equipment housing unit that protects and organizes electronic equipment. Also known as an equipment rack.","tags":["Project Management"],"text":"An equipment housing unit that protects and organizes electronic equipment. Also known as an equipment rack."},{"title":"rack elevation diagram","url":"https://sane-av.github.io/glossary/?search=rack%20elevation%20diagram","type":"Glossary","snippet":"A rack elevation diagram is a pictorial representation of the front of a rack and the location of each piece of equipment within that rack, typically labeling the number of RUs used for each piece of equipment.","tags":["Project Management"],"text":"A rack elevation diagram is a pictorial representation of the front of a rack and the location of each piece of equipment within that rack, typically labeling the number of RUs used for each piece of equipment."},{"title":"RU (rack unit)","url":"https://sane-av.github.io/glossary/?search=rack%20unit","type":"Glossary","snippet":"A unit of measure of the vertical space in a rack. One RU equals 1.75 inches (44.5mm).","tags":["Project Management"],"text":"A unit of measure of the vertical space in a rack. One RU equals 1.75 inches (44.5mm)."},{"title":"RF (radio frequency)","url":"https://sane-av.github.io/glossary/?search=radio%20frequency","type":"Glossary","snippet":"The portion of the electromagnetic spectrum that is suitable for radio communications. Generally, this is considered to be from 10kHz up to 300MHz. This range extends to 300GHz if the microwave portion of the spectrum is included.","tags":["General"],"text":"The portion of the electromagnetic spectrum that is suitable for radio communications. Generally, this is considered to be from 10kHz up to 300MHz. This range extends to 300GHz if the microwave portion of the spectrum is included."},{"title":"RFI (radio frequency interference)","url":"https://sane-av.github.io/glossary/?search=radio%20frequency%20interference","type":"Glossary","snippet":"Radiated electromagnetic energy that interferes with or disturbs an electrical circuit.","tags":["Electrical"],"text":"Radiated electromagnetic energy that interferes with or disturbs an electrical circuit."},{"title":"rarefaction","url":"https://sane-av.github.io/glossary/?search=rarefaction","type":"Glossary","snippet":"A decrease of density and pressure in a compressible medium such as air.","tags":["General"],"text":"A decrease of density and pressure in a compressible medium such as air."},{"title":"ratio","url":"https://sane-av.github.io/glossary/?search=ratio","type":"Glossary","snippet":"A mathematical expression that represents the relationship between the quantities of numbers of the same kind. A ratio is typically written as X:Y or X/Y.","tags":["General"],"text":"A mathematical expression that represents the relationship between the quantities of numbers of the same kind. A ratio is typically written as X:Y or X/Y."},{"title":"RCA connector","url":"https://sane-av.github.io/glossary/?search=RCA%20connector","type":"Glossary","snippet":"The North American name for the phono connector, a coaxial connector most often used with line-level audio signals and consumer composite video signals.","tags":["Audio","Video","Cabling"],"text":"The North American name for the phono connector, a coaxial connector most often used with line-level audio signals and consumer composite video signals."},{"title":"RCBO","url":"https://sane-av.github.io/glossary/?search=RCBO","type":"Glossary","snippet":"Residual current breaker with overcurrent protection. An electrical protection device that combines the functionality of a miniature circuit breaker (MCB) and a residual current detector/residual current circuit breaker (RCD/RCCB).","tags":["Electrical"],"text":"Residual current breaker with overcurrent protection. An electrical protection device that combines the functionality of a miniature circuit breaker (MCB) and a residual current detector/residual current circuit breaker (RCD/RCCB)."},{"title":"RCD","url":"https://sane-av.github.io/glossary/?search=RCD","type":"Glossary","snippet":"A safety device that de-energizes a circuit (or a portion of that circuit) within an established period of time when a current to ground exceeds a specified level. Also known as a residual current circuit breaker (RCCB). Similar in function to an earth leakage circuit breaker (ELCB), a ground-fault circuit interrupter (GFCI), or a core balance relay (CBR). Abbreviation for residual current device.","tags":["Electrical"],"text":"A safety device that de-energizes a circuit (or a portion of that circuit) within an established period of time when a current to ground exceeds a specified level. Also known as a residual current circuit breaker (RCCB). Similar in function to an earth leakage circuit breaker (ELCB), a ground-fault circuit interrupter (GFCI), or a core balance relay (CBR). Abbreviation for residual current device."},{"title":"reactance","url":"https://sane-av.github.io/glossary/?search=reactance","type":"Glossary","snippet":"Opposition to current flow in a circuit resulting from the reaction of the capacitance and inductance in the circuit. Measured in ohms (Ω). The symbol for reactance is X.","tags":["Electrical"],"text":"Opposition to current flow in a circuit resulting from the reaction of the capacitance and inductance in the circuit. Measured in ohms (Ω). The symbol for reactance is X."},{"title":"rear-screen projection","url":"https://sane-av.github.io/glossary/?search=rear-screen%20projection","type":"Glossary","snippet":"A system in which the image is projected toward the audience through a translucent screen material for viewing from the opposite side.","tags":["Video"],"text":"A system in which the image is projected toward the audience through a translucent screen material for viewing from the opposite side."},{"title":"reference level","url":"https://sane-av.github.io/glossary/?search=reference%20level","type":"Glossary","snippet":"In the context of decibel measurements, the reference level is the established starting point represented by 0dB. The reference level varies according to unit and application.","tags":["General"],"text":"In the context of decibel measurements, the reference level is the established starting point represented by 0dB. The reference level varies according to unit and application."},{"title":"reference point","url":"https://sane-av.github.io/glossary/?search=reference%20point","type":"Glossary","snippet":"The point of zero potential used as the voltage reference for a circuit.","tags":["Electrical"],"text":"The point of zero potential used as the voltage reference for a circuit."},{"title":"RCP (reflected ceiling plan)","url":"https://sane-av.github.io/glossary/?search=reflected%20ceiling%20plan","type":"Glossary","snippet":"A plan used to illustrate elements in the ceiling with respect to the floor. It should be interpreted as though the floor is a mirrored surface, reflecting the features within the ceiling.","tags":["Project Management"],"text":"A plan used to illustrate elements in the ceiling with respect to the floor. It should be interpreted as though the floor is a mirrored surface, reflecting the features within the ceiling."},{"title":"reflecting server","url":"https://sane-av.github.io/glossary/?search=reflecting%20server","type":"Glossary","snippet":"A caching server in a content delivery network (CDN). Ingests a unicast stream and broadcasts a multicast stream.","tags":["Networking"],"text":"A caching server in a content delivery network (CDN). Ingests a unicast stream and broadcasts a multicast stream."},{"title":"reflection","url":"https://sane-av.github.io/glossary/?search=reflection","type":"Glossary","snippet":"Electromagnetic energy (light, radio waves, etc.) or sound energy that has been redirected by a surface.","tags":["General"],"text":"Electromagnetic energy (light, radio waves, etc.) or sound energy that has been redirected by a surface."},{"title":"reflective technology","url":"https://sane-av.github.io/glossary/?search=reflective%20technology","type":"Glossary","snippet":"A display device that reflects light to create an image.","tags":["Video"],"text":"A display device that reflects light to create an image."},{"title":"refraction","url":"https://sane-av.github.io/glossary/?search=refraction","type":"Glossary","snippet":"The bending or changing of the direction of a light ray when passing between transparent mediums such as air, water, glass, or a vacuum. The refractive index of a material is a measure of the speed that light travels through the medium in comparison to its speed through a vacuum.","tags":["General"],"text":"The bending or changing of the direction of a light ray when passing between transparent mediums such as air, water, glass, or a vacuum. The refractive index of a material is a measure of the speed that light travels through the medium in comparison to its speed through a vacuum."},{"title":"refresh rate","url":"https://sane-av.github.io/glossary/?search=refresh%20rate","type":"Glossary","snippet":"The number of times per second a display device will update the display of a received image.","tags":["Video"],"text":"The number of times per second a display device will update the display of a received image."},{"title":"release time","url":"https://sane-av.github.io/glossary/?search=release%20time","type":"Glossary","snippet":"The release time of an audio compressor determines how quickly the volume increases when an audio signal returns below the threshold.","tags":["Audio"],"text":"The release time of an audio compressor determines how quickly the volume increases when an audio signal returns below the threshold."},{"title":"relocatable power tap","url":"https://sane-av.github.io/glossary/?search=relocatable%20power%20tap","type":"Glossary","snippet":"The North American term for a cord-connected product rated 250V AC or less and 20A or less with multiple receptacles. This tap is intended only for indoor use and plugged directly into a branch circuit. It is not intended to be connected to another relocatable power tap. See power strip.","tags":["Electrical"],"text":"The North American term for a cord-connected product rated 250V AC or less and 20A or less with multiple receptacles. This tap is intended only for indoor use and plugged directly into a branch circuit. It is not intended to be connected to another relocatable power tap. See power strip."},{"title":"reserve DHCP","url":"https://sane-av.github.io/glossary/?search=reserve%20DHCP","type":"Glossary","snippet":"A hybrid approach to IP address allocation. Using reserve DHCP, a block of addresses is reserved for devices requiring a static IP address. The remaining IP addresses in the subnet pool are assigned dynamically using DHCP.","tags":["Networking"],"text":"A hybrid approach to IP address allocation. Using reserve DHCP, a block of addresses is reserved for devices requiring a static IP address. The remaining IP addresses in the subnet pool are assigned dynamically using DHCP."},{"title":"RCD (residual current device)","url":"https://sane-av.github.io/glossary/?search=residual%20current%20device","type":"Glossary","snippet":"A safety device that de-energizes a circuit (or a portion of that circuit) within an established period of time when a current to ground exceeds a specified level. Also known as a residual current circuit breaker (RCCB). Similar in function to an earth leakage circuit breaker (ELCB), a ground-fault circuit interrupter (GFCI), or a core balance relay (CBR).","tags":["Electrical"],"text":"A safety device that de-energizes a circuit (or a portion of that circuit) within an established period of time when a current to ground exceeds a specified level. Also known as a residual current circuit breaker (RCCB). Similar in function to an earth leakage circuit breaker (ELCB), a ground-fault circuit interrupter (GFCI), or a core balance relay (CBR)."},{"title":"resistance","url":"https://sane-av.github.io/glossary/?search=resistance","type":"Glossary","snippet":"The property of a material to impede the flow of electrical current. Measured in ohms (Ω). The symbol for resistance is R.","tags":["Electrical"],"text":"The property of a material to impede the flow of electrical current. Measured in ohms (Ω). The symbol for resistance is R."},{"title":"resistor","url":"https://sane-av.github.io/glossary/?search=resistor","type":"Glossary","snippet":"A passive electrical device that produces opposition to current flow. Current passes through a resistor in direct proportion to voltage, independent of frequency. The relationship between voltage across and current through a resistor is defined in Ohm’s law.","tags":["Electrical","Standards"],"text":"A passive electrical device that produces opposition to current flow. Current passes through a resistor in direct proportion to voltage, independent of frequency. The relationship between voltage across and current through a resistor is defined in Ohm’s law."},{"title":"resolution","url":"https://sane-av.github.io/glossary/?search=resolution","type":"Glossary","snippet":"1. The amount of detail in an image. 2. The number of picture elements (pixels) in a display.","tags":["Video"],"text":"1. The amount of detail in an image. 2. The number of picture elements (pixels) in a display."},{"title":"reverberant sound","url":"https://sane-av.github.io/glossary/?search=reverberant%20sound","type":"Glossary","snippet":"Sound waves that bounce off multiple surfaces before reaching the listener but arrive at the listener’s ears later than early reflected sound.","tags":["General"],"text":"Sound waves that bounce off multiple surfaces before reaching the listener but arrive at the listener’s ears later than early reflected sound."},{"title":"reverberation","url":"https://sane-av.github.io/glossary/?search=reverberation","type":"Glossary","snippet":"Numerous persistent reflections of sound energy.","tags":["Acoustics"],"text":"Numerous persistent reflections of sound energy."},{"title":"reverse phase-control dimming","url":"https://sane-av.github.io/glossary/?search=reverse%20phase-control%20dimming","type":"Glossary","snippet":"A method of electronic dimming that progressively removes the trailing edge of each half-cycle of the AC power.","tags":["Electrical","Lighting"],"text":"A method of electronic dimming that progressively removes the trailing edge of each half-cycle of the AC power."},{"title":"RF","url":"https://sane-av.github.io/glossary/?search=RF","type":"Glossary","snippet":"The portion of the electromagnetic spectrum that is suitable for radio communications. Generally considered to be from 10kHz up to 300MHz, extending to 300GHz if the microwave portion of the spectrum is included. Abbreviation for radio frequency.","tags":["General"],"text":"The portion of the electromagnetic spectrum that is suitable for radio communications. Generally considered to be from 10kHz up to 300MHz, extending to 300GHz if the microwave portion of the spectrum is included. Abbreviation for radio frequency."},{"title":"RF control","url":"https://sane-av.github.io/glossary/?search=RF%20control","type":"Glossary","snippet":"A method of control employing RF wireless signaling. RF control systems vary in complexity from simple one-way on/off signals to high-bandwidth, multichannel, bi-directional systems with complex user interfaces and rich feedback. Wireless control may use many formats, including Wi-Fi, DECT, ISM, Bluetooth, Zigbee, UWB, or LTE frequencies and signaling protocols.","tags":["Audio","Networking","Lighting"],"text":"A method of control employing RF wireless signaling. RF control systems vary in complexity from simple one-way on/off signals to high-bandwidth, multichannel, bi-directional systems with complex user interfaces and rich feedback. Wireless control may use many formats, including Wi-Fi, DECT, ISM, Bluetooth, Zigbee, UWB, or LTE frequencies and signaling protocols."},{"title":"RF distribution system","url":"https://sane-av.github.io/glossary/?search=RF%20distribution%20system","type":"Glossary","snippet":"A closed-circuit television distribution system with each of the composite video and audio program signals modulated onto a radio frequency carrier signal for distribution via RF cables. Receiving devices must have a demodulator capable of extracting the separate program channels.","tags":["Audio","Video","Networking","Electrical","Cabling"],"text":"A closed-circuit television distribution system with each of the composite video and audio program signals modulated onto a radio frequency carrier signal for distribution via RF cables. Receiving devices must have a demodulator capable of extracting the separate program channels."},{"title":"RGBHV signal","url":"https://sane-av.github.io/glossary/?search=RGBHV%20signal","type":"Glossary","snippet":"A high-bandwidth video signal with separate conductors for the red signal, green signal, blue signal, horizontal sync, and vertical sync.","tags":["Video","Electrical"],"text":"A high-bandwidth video signal with separate conductors for the red signal, green signal, blue signal, horizontal sync, and vertical sync."},{"title":"RGBS signal","url":"https://sane-av.github.io/glossary/?search=RGBS%20signal","type":"Glossary","snippet":"A four-component video signal composed of a red signal, a green signal, a blue signal, and a composite sync signal.","tags":["Video"],"text":"A four-component video signal composed of a red signal, a green signal, a blue signal, and a composite sync signal."},{"title":"rigid metal conduit","url":"https://sane-av.github.io/glossary/?search=rigid%20metal%20conduit","type":"Glossary","snippet":"A rigid metal conduit, called just rigid in North America, is the heaviest electrical conduit and offers the best physical and EMI protection.","tags":["Cabling"],"text":"A rigid metal conduit, called just rigid in North America, is the heaviest electrical conduit and offers the best physical and EMI protection."},{"title":"rigid nonmetallic tubing","url":"https://sane-av.github.io/glossary/?search=rigid%20nonmetallic%20tubing","type":"Glossary","snippet":"Rigid nonmetallic tubing is very stiff with a thick wall but lightweight. It is similar to plumbing tubing. Because it is not flexible, it is available in preformed pieces at various angles.","tags":["Cabling"],"text":"Rigid nonmetallic tubing is very stiff with a thick wall but lightweight. It is similar to plumbing tubing. Because it is not flexible, it is available in preformed pieces at various angles."},{"title":"ring","url":"https://sane-av.github.io/glossary/?search=ring","type":"Glossary","snippet":"A network topology that connects terminals, computers, or nodes in a continuous loop.","tags":["Networking"],"text":"A network topology that connects terminals, computers, or nodes in a continuous loop."},{"title":"risk","url":"https://sane-av.github.io/glossary/?search=risk","type":"Glossary","snippet":"The potential for an unwanted or adverse impact on organizational operations resulting from an occurrence involving AV and information systems, given the potential impact of a specific threat and the likelihood of that threat taking place.","tags":["Security"],"text":"The potential for an unwanted or adverse impact on organizational operations resulting from an occurrence involving AV and information systems, given the potential impact of a specific threat and the likelihood of that threat taking place."},{"title":"risk analysis","url":"https://sane-av.github.io/glossary/?search=risk%20analysis","type":"Glossary","snippet":"The process of collecting information regarding the risks of an AV system and assigning values to each of those risks.","tags":["Security"],"text":"The process of collecting information regarding the risks of an AV system and assigning values to each of those risks."},{"title":"risk mitigation plan","url":"https://sane-av.github.io/glossary/?search=risk%20mitigation%20plan","type":"Glossary","snippet":"The set of steps an organization takes to evaluate and prioritize its risks and implement countermeasures intended to reduce the likelihood of a risk occurring or its impact.","tags":["Security"],"text":"The set of steps an organization takes to evaluate and prioritize its risks and implement countermeasures intended to reduce the likelihood of a risk occurring or its impact."},{"title":"risk register","url":"https://sane-av.github.io/glossary/?search=risk%20register","type":"Glossary","snippet":"A document created to record the risks an organization faces to its AV and information systems. This information includes a detailed description of each risk, including its probability, severity and impact, and steps to mitigate it.","tags":["Security"],"text":"A document created to record the risks an organization faces to its AV and information systems. This information includes a detailed description of each risk, including its probability, severity and impact, and steps to mitigate it."},{"title":"room criteria rating","url":"https://sane-av.github.io/glossary/?search=room%20criteria%20rating","type":"Glossary","snippet":"A single number rating that quantifies the tonal characteristics of background noise, including the characteristics of ventilation noise, such as rumble or hiss.","tags":["Audio","Electrical"],"text":"A single number rating that quantifies the tonal characteristics of background noise, including the characteristics of ventilation noise, such as rumble or hiss."},{"title":"room mode","url":"https://sane-av.github.io/glossary/?search=room%20mode","type":"Glossary","snippet":"An acoustic wave-interference phenomenon that occurs between the parallel surfaces of an enclosure where the dimension between those parallel surfaces equals one-half wavelength (and the harmonics thereof) of a frequency. The wave is thus reflected on itself out of phase, creating location-specific areas of maximum and minimum pressure.","tags":["Acoustics","Electrical"],"text":"An acoustic wave-interference phenomenon that occurs between the parallel surfaces of an enclosure where the dimension between those parallel surfaces equals one-half wavelength (and the harmonics thereof) of a frequency. The wave is thus reflected on itself out of phase, creating location-specific areas of maximum and minimum pressure."},{"title":"router","url":"https://sane-av.github.io/glossary/?search=router","type":"Glossary","snippet":"A network device that forwards data packets between computer networks. It operates on the OSI Network layer (layer 3).","tags":["Networking"],"text":"A network device that forwards data packets between computer networks. It operates on the OSI Network layer (layer 3)."},{"title":"RS-232","url":"https://sane-av.github.io/glossary/?search=RS-232","type":"Glossary","snippet":"A point-to-point serial data protocol. The interface between data terminal equipment and data circuitterminating equipment employing serial binary data interchange. It supports a half-duplex mode of operation with one driver and one receiver. At a cable length of 15m (50ft), RS-232 supports a data rate of up to 19.2kbps. At its maximum cable length of 900m (3,000ft), it supports a data rate of 2.4kbps.","tags":["Audio","Networking","Electrical","Cabling","Signal Processing"],"text":"A point-to-point serial data protocol. The interface between data terminal equipment and data circuitterminating equipment employing serial binary data interchange. It supports a half-duplex mode of operation with one driver and one receiver. At a cable length of 15m (50ft), RS-232 supports a data rate of up to 19.2kbps. At its maximum cable length of 900m (3,000ft), it supports a data rate of 2.4kbps."},{"title":"RS-422","url":"https://sane-av.github.io/glossary/?search=RS-422","type":"Glossary","snippet":"A multidrop serial data protocol. Provides the electrical characteristics of balanced-voltage digital interface circuits. It is a balanced signal with one driver and up to 10 receivers with multidrop capability. The maximum cable length for RS-422 is 1,220m (4,000ft) with a data rate of 10Mbps.","tags":["Audio","Electrical","Cabling","Signal Processing"],"text":"A multidrop serial data protocol. Provides the electrical characteristics of balanced-voltage digital interface circuits. It is a balanced signal with one driver and up to 10 receivers with multidrop capability. The maximum cable length for RS-422 is 1,220m (4,000ft) with a data rate of 10Mbps."},{"title":"RS-485","url":"https://sane-av.github.io/glossary/?search=RS-485","type":"Glossary","snippet":"A transmission line serial data protocol. Supports a differential mode of operation with 32 tri-state drivers and 32 tri-state receivers and multidrop capability. The maximum cable length for RS-485 is 1.2km (4,000ft) with a data rate of 10Mbps.","tags":["Cabling","Signal Processing"],"text":"A transmission line serial data protocol. Supports a differential mode of operation with 32 tri-state drivers and 32 tri-state receivers and multidrop capability. The maximum cable length for RS-485 is 1.2km (4,000ft) with a data rate of 10Mbps."},{"title":"RsGsBs","url":"https://sane-av.github.io/glossary/?search=RsGsBs","type":"Glossary","snippet":"A video transmission system using red, green, and blue signals with composite sync added to each color channel. This requires three cables to carry the entire signal. It is often referred to as RGB sync on all three.","tags":["Video","Cabling"],"text":"A video transmission system using red, green, and blue signals with composite sync added to each color channel. This requires three cables to carry the entire signal. It is often referred to as RGB sync on all three."},{"title":"RT60","url":"https://sane-av.github.io/glossary/?search=RT60","type":"Glossary","snippet":"The time taken for the energy in an initially steady reverberant sound field to decay by 60dB after the source of the sound ceases.","tags":["Acoustics"],"text":"The time taken for the energy in an initially steady reverberant sound field to decay by 60dB after the source of the sound ceases."},{"title":"RU","url":"https://sane-av.github.io/glossary/?search=RU","type":"Glossary","snippet":"1. See rack unit (RU). 2. A CTS renewal unit. The completion of renewal unit–accredited training is required by CTS, CTS-I, and CTS-D certification holders to maintain the currency of their certification.","tags":["Project Management"],"text":"1. See rack unit (RU). 2. A CTS renewal unit. The completion of renewal unit–accredited training is required by CTS, CTS-I, and CTS-D certification holders to maintain the currency of their certification."},{"title":"sabin","url":"https://sane-av.github.io/glossary/?search=sabin","type":"Glossary","snippet":"An index of sound absorption efficiency. Possible values range from 1.00 (absorbs everything) to 0.00 (absorbs nothing).","tags":["Acoustics"],"text":"An index of sound absorption efficiency. Possible values range from 1.00 (absorbs everything) to 0.00 (absorbs nothing)."},{"title":"sampling rate","url":"https://sane-av.github.io/glossary/?search=sampling%20rate","type":"Glossary","snippet":"The number of samples taken per unit of time when converting a continuous analog signal to a digital signal.","tags":["Audio","Signal Processing"],"text":"The number of samples taken per unit of time when converting a continuous analog signal to a digital signal."},{"title":"scale","url":"https://sane-av.github.io/glossary/?search=scale","type":"Glossary","snippet":"The representation of a number by another number differing by a fixed ratio.","tags":["General"],"text":"The representation of a number by another number differing by a fixed ratio."},{"title":"scale drawing","url":"https://sane-av.github.io/glossary/?search=scale%20drawing","type":"Glossary","snippet":"A drawing that shows objects in accurate proportion, with all dimensions enlarged or reduced by a fixed ratio.","tags":["Project Management"],"text":"A drawing that shows objects in accurate proportion, with all dimensions enlarged or reduced by a fixed ratio."},{"title":"scaler","url":"https://sane-av.github.io/glossary/?search=scaler","type":"Glossary","snippet":"A processor that changes the resolution of an image without changing its apparent content. Scaling may be required when the image resolution does not match the resolution of the display device.","tags":["Video","Signal Processing"],"text":"A processor that changes the resolution of an image without changing its apparent content. Scaling may be required when the image resolution does not match the resolution of the display device."},{"title":"scan rate","url":"https://sane-av.github.io/glossary/?search=scan%20rate","type":"Glossary","snippet":"The rate at which a raster-scan image is displayed. Horizontal scan rate is the rate at which a single horizontal line is displayed. Vertical scan rate (refresh rate) is the rate at which an entire screen image is displayed.","tags":["Video"],"text":"The rate at which a raster-scan image is displayed. Horizontal scan rate is the rate at which a single horizontal line is displayed. Vertical scan rate (refresh rate) is the rate at which an entire screen image is displayed."},{"title":"scattering","url":"https://sane-av.github.io/glossary/?search=scattering","type":"Glossary","snippet":"When a wave strikes a textured surface, the incoming waves are reflected in multiple directions because the surface is uneven.","tags":["General"],"text":"When a wave strikes a textured surface, the incoming waves are reflected in multiple directions because the surface is uneven."},{"title":"scene","url":"https://sane-av.github.io/glossary/?search=scene","type":"Glossary","snippet":"A recallable preset or state of lighting levels for one or more zones.","tags":["Systems & Control"],"text":"A recallable preset or state of lighting levels for one or more zones."},{"title":"scope statement","url":"https://sane-av.github.io/glossary/?search=scope%20statement","type":"Glossary","snippet":"A written agreement between the client, the project sponsor, the key stakeholders, and the project team that defines the boundaries of the project.","tags":["Project Management"],"text":"A written agreement between the client, the project sponsor, the key stakeholders, and the project team that defines the boundaries of the project."},{"title":"SCR","url":"https://sane-av.github.io/glossary/?search=SCR","type":"Glossary","snippet":"The silicon-controlled rectifier (SCR) is a semiconductor from the thyristor family of four-layer powerswitching devices. As it is a rectifier, it must be used in an inverse-pair to control both the positive and negative half-cycles of mains power. It was the first type of solid-state device to be used for power control and phase-control dimming.","tags":["Electrical","Lighting"],"text":"The silicon-controlled rectifier (SCR) is a semiconductor from the thyristor family of four-layer powerswitching devices. As it is a rectifier, it must be used in an inverse-pair to control both the positive and negative half-cycles of mains power. It was the first type of solid-state device to be used for power control and phase-control dimming."},{"title":"screen gain","url":"https://sane-av.github.io/glossary/?search=screen%20gain","type":"Glossary","snippet":"The ability of a projection screen to concentrate the light reflected from it. Gain is compared to the reflection of a matte-white screen, which reflects light uniformly in all directions (a gain of 1).","tags":["Audio","Video"],"text":"The ability of a projection screen to concentrate the light reflected from it. Gain is compared to the reflection of a matte-white screen, which reflects light uniformly in all directions (a gain of 1)."},{"title":"SDTV","url":"https://sane-av.github.io/glossary/?search=SDTV","type":"Glossary","snippet":"Standard-definition television. It has a 4:3 aspect ratio and a resolution of 576i for PAL and SECAM and 480i for NTSC.","tags":["Video"],"text":"Standard-definition television. It has a 4:3 aspect ratio and a resolution of 576i for PAL and SECAM and 480i for NTSC."},{"title":"section drawing","url":"https://sane-av.github.io/glossary/?search=section%20drawing","type":"Glossary","snippet":"A section drawing is a view of the interior of a building in the vertical plane. Section drawings show bisected features, which allows you to view what is behind them.","tags":["Project Management"],"text":"A section drawing is a view of the interior of a building in the vertical plane. Section drawings show bisected features, which allows you to view what is behind them."},{"title":"security policy","url":"https://sane-av.github.io/glossary/?search=security%20policy","type":"Glossary","snippet":"A set of rules that establish the acceptable use of an organization’s AV and IT systems based on the risk that each system faces and the measures taken to address those risks.","tags":["Security"],"text":"A set of rules that establish the acceptable use of an organization’s AV and IT systems based on the risk that each system faces and the measures taken to address those risks."},{"title":"sensitivity specification","url":"https://sane-av.github.io/glossary/?search=sensitivity%20specification","type":"Glossary","snippet":"The measure of a device’s capacity to convert one form of energy into another form of energy. Usually stated as a ratio of input units to output units, such as mV/Pa for microphones.","tags":["Audio"],"text":"The measure of a device’s capacity to convert one form of energy into another form of energy. Usually stated as a ratio of input units to output units, such as mV/Pa for microphones."},{"title":"SDI (serial digital interface)","url":"https://sane-av.github.io/glossary/?search=serial%20digital%20interface","type":"Glossary","snippet":"A set of serial data standards to transport digital AV data over BNC-terminated 75Ω coaxial cable or over optical fiber. Variants include HD-SDI for HD video, 6G-SDI (6Gbps) for 4kp30, 12G-SDI (12Gbps) for 4kp60, and 24G-SDI (24Gbps) for 8kp30 video.","tags":["Video","Cabling"],"text":"A set of serial data standards to transport digital AV data over BNC-terminated 75Ω coaxial cable or over optical fiber. Variants include HD-SDI for HD video, 6G-SDI (6Gbps) for 4kp30, 12G-SDI (12Gbps) for 4kp60, and 24G-SDI (24Gbps) for 8kp30 video."},{"title":"series circuit","url":"https://sane-av.github.io/glossary/?search=series%20circuit","type":"Glossary","snippet":"A circuit arrangement where all the current supplied by the source will flow through the entire circuit. While all the current flows through all the circuit elements, the voltage is divided between the loads and the wires that connect them.","tags":["Electrical"],"text":"A circuit arrangement where all the current supplied by the source will flow through the entire circuit. While all the current flows through all the circuit elements, the voltage is divided between the loads and the wires that connect them."},{"title":"series/parallel loudspeaker circuit","url":"https://sane-av.github.io/glossary/?search=series%2Fparallel%20loudspeaker%20circuit","type":"Glossary","snippet":"An arrangement of loudspeakers where some are wired in parallel and some are wired in series. Typically, groups of loudspeakers are wired in parallel, then those groups are connected to the amplifier in series.","tags":["Audio","Electrical"],"text":"An arrangement of loudspeakers where some are wired in parallel and some are wired in series. Typically, groups of loudspeakers are wired in parallel, then those groups are connected to the amplifier in series."},{"title":"server","url":"https://sane-av.github.io/glossary/?search=server","type":"Glossary","snippet":"A computer system that shares resources and services with other connected devices.","tags":["General"],"text":"A computer system that shares resources and services with other connected devices."},{"title":"SLA (service-level agreement)","url":"https://sane-av.github.io/glossary/?search=service-level%20agreement","type":"Glossary","snippet":"A document used to record an agreement between a service provider and a customer. It describes the services to be provided, documents service-level targets, and specifies the roles and responsibilities of the service provider(s) and the customer(s).","tags":["Project Management"],"text":"A document used to record an agreement between a service provider and a customer. It describes the services to be provided, documents service-level targets, and specifies the roles and responsibilities of the service provider(s) and the customer(s)."},{"title":"SBC (session border controller)","url":"https://sane-av.github.io/glossary/?search=session%20border%20controller","type":"Glossary","snippet":"A device used in VoIP networks to control the signaling and media streams involved in setting up, conducting, and tearing down calls. The SBC enforces security, QoS, and admission control over VoIP sessions.","tags":["Networking"],"text":"A device used in VoIP networks to control the signaling and media streams involved in setting up, conducting, and tearing down calls. The SBC enforces security, QoS, and admission control over VoIP sessions."},{"title":"shear force","url":"https://sane-av.github.io/glossary/?search=shear%20force","type":"Glossary","snippet":"The force exerted on an object in the direction of the object’s cross section. In the case of a wall-mounting bolt, the shear force across the bolt caused by the gravitational load of the object it is supporting.","tags":["Cabling"],"text":"The force exerted on an object in the direction of the object’s cross section. In the case of a wall-mounting bolt, the shear force across the bolt caused by the gravitational load of the object it is supporting."},{"title":"shield or screen","url":"https://sane-av.github.io/glossary/?search=shield%20or%20screen","type":"Glossary","snippet":"A grounded conductive partition placed between two regions of space to control the propagation of electric and magnetic fields between them. The screen or shield acts as a Faraday cage. It can be the chassis (metallic box) that houses an electronic device or the conductive enclosure (aluminum foil, conductive polymer, or copper braid) that surrounds a screened/shielded wire or cable.","tags":["Electrical","Cabling"],"text":"A grounded conductive partition placed between two regions of space to control the propagation of electric and magnetic fields between them. The screen or shield acts as a Faraday cage. It can be the chassis (metallic box) that houses an electronic device or the conductive enclosure (aluminum foil, conductive polymer, or copper braid) that surrounds a screened/shielded wire or cable."},{"title":"shielded twisted-pair cable","url":"https://sane-av.github.io/glossary/?search=shielded%20twisted-pair%20cable","type":"Glossary","snippet":"A cable that contains one or more twisted-pairs of conductors inside an overall shield. Known variously as STP, or FTP when the shield is constructed of foil.","tags":["Electrical","Cabling"],"text":"A cable that contains one or more twisted-pairs of conductors inside an overall shield. Known variously as STP, or FTP when the shield is constructed of foil."},{"title":"shotgun microphone","url":"https://sane-av.github.io/glossary/?search=shotgun%20microphone","type":"Glossary","snippet":"A long, cylindrical, highly sensitive microphone with a very narrow pickup pattern.","tags":["Audio"],"text":"A long, cylindrical, highly sensitive microphone with a very narrow pickup pattern."},{"title":"sightline","url":"https://sane-av.github.io/glossary/?search=sightline","type":"Glossary","snippet":"The line of sight between a viewer and an object that needs to be seen.","tags":["Video"],"text":"The line of sight between a viewer and an object that needs to be seen."},{"title":"signal flow","url":"https://sane-av.github.io/glossary/?search=signal%20flow","type":"Glossary","snippet":"The traceable path of signals through a system.","tags":["General"],"text":"The traceable path of signals through a system."},{"title":"signal generator","url":"https://sane-av.github.io/glossary/?search=signal%20generator","type":"Glossary","snippet":"A test instrument that produces calibrated electronic signals for the testing or alignment of electronic circuits or systems.","tags":["Electrical"],"text":"A test instrument that produces calibrated electronic signals for the testing or alignment of electronic circuits or systems."},{"title":"signal ground","url":"https://sane-av.github.io/glossary/?search=signal%20ground","type":"Glossary","snippet":"1. A 0V (zero volt) point of no potential that serves as the circuit reference. 2. A low-impedance path for the current to return to the source.","tags":["Electrical"],"text":"1. A 0V (zero volt) point of no potential that serves as the circuit reference. 2. A low-impedance path for the current to return to the source."},{"title":"signal-to-noise (S/N) ratio","url":"https://sane-av.github.io/glossary/?search=signal-to-noise%20(S%2FN)%20ratio","type":"Glossary","snippet":"The ratio, usually measured in decibels, between an information signal and the accompanying noninformation noise. The higher this ratio, the cleaner the signal.","tags":["Signal Processing"],"text":"The ratio, usually measured in decibels, between an information signal and the accompanying noninformation noise. The higher this ratio, the cleaner the signal."},{"title":"SNMP (Simple Network Management Protocol)","url":"https://sane-av.github.io/glossary/?search=Simple%20Network%20Management%20Protocol","type":"Glossary","snippet":"A set of Internet Engineering Task Force (IETF) standards for network management.","tags":["Networking","Standards"],"text":"A set of Internet Engineering Task Force (IETF) standards for network management."},{"title":"SPE (single-pair Ethernet)","url":"https://sane-av.github.io/glossary/?search=single-pair%20Ethernet","type":"Glossary","snippet":"An Ethernet variant based on a single 100Ω twisted-pair cable rather than the more-common four-pair configuration. Originally developed for automotive and industrial control applications, it has been adopted for Internet of Things (IOT) and other remotely-located devices. Capable of full-duplex data transmission speeds of up to 1Gbps over 15m (50ft), and extending to up to 1km (3,280ft) at 10Mbps. Most commonly used connectors used are the IEC 63171-1 (Type 1) “LC” style and the IEC 63171-6 industrial style. Used in conjunction with a PoE (Power over Ethernet)/PoDL (Power over Data Line) feed of up to 50w, remote Ethernet devices such as video cameras can be powered and operated over a single-pair cable.","tags":["Video","Networking","Cabling","Systems & Control"],"text":"An Ethernet variant based on a single 100Ω twisted-pair cable rather than the more-common four-pair configuration. Originally developed for automotive and industrial control applications, it has been adopted for Internet of Things (IOT) and other remotely-located devices. Capable of full-duplex data transmission speeds of up to 1Gbps over 15m (50ft), and extending to up to 1km (3,280ft) at 10Mbps. Most commonly used connectors used are the IEC 63171-1 (Type 1) “LC” style and the IEC 63171-6 industrial style. Used in conjunction with a PoE (Power over Ethernet)/PoDL (Power over Data Line) feed of up to 50w, remote Ethernet devices such as video cameras can be powered and operated over a single-pair cable."},{"title":"single-phase power","url":"https://sane-av.github.io/glossary/?search=single-phase%20power","type":"Glossary","snippet":"Alternating-current electrical power supplied by two current-carrying conductors. This type of supply is used for residential and many light-commercial applications.","tags":["Electrical"],"text":"Alternating-current electrical power supplied by two current-carrying conductors. This type of supply is used for residential and many light-commercial applications."},{"title":"SPG (single-point ground)","url":"https://sane-av.github.io/glossary/?search=single-point%20ground","type":"Glossary","snippet":"In the context of IEEE Standard 1100, refers to implementation of an isolated equipment grounding configuration for the purposes of minimizing problems caused by circulating current in ground loops.","tags":["Electrical","Standards"],"text":"In the context of IEEE Standard 1100, refers to implementation of an isolated equipment grounding configuration for the purposes of minimizing problems caused by circulating current in ground loops."},{"title":"socket","url":"https://sane-av.github.io/glossary/?search=socket","type":"Glossary","snippet":"In a TCP/IP network, the combined port number, Transport-layer (layer 4) protocol identifier, and IP addresses of communicating end systems. A socket uniquely identifies a session of a given transport protocol.","tags":["Networking"],"text":"In a TCP/IP network, the combined port number, Transport-layer (layer 4) protocol identifier, and IP addresses of communicating end systems. A socket uniquely identifies a session of a given transport protocol."},{"title":"software patch","url":"https://sane-av.github.io/glossary/?search=software%20patch","type":"Glossary","snippet":"A piece of computer code used to update an AV or IT program with the intention of fixing or improving it. The update may address known security vulnerabilities to limit their exploitation by intruders.","tags":["Security"],"text":"A piece of computer code used to update an AV or IT program with the intention of fixing or improving it. The update may address known security vulnerabilities to limit their exploitation by intruders."},{"title":"SPL (sound pressure level)","url":"https://sane-av.github.io/glossary/?search=sound%20pressure%20level","type":"Glossary","snippet":"The effective pressure level of a sound, usually stated in relation to a reference pressure such as 20µPa (the threshold of human hearing). In the context of Industry Standard A102.01:2017, expressed in unweighted decibels.","tags":["Acoustics","Standards"],"text":"The effective pressure level of a sound, usually stated in relation to a reference pressure such as 20µPa (the threshold of human hearing). In the context of Industry Standard A102.01:2017, expressed in unweighted decibels."},{"title":"sound reinforcement system","url":"https://sane-av.github.io/glossary/?search=sound%20reinforcement%20system","type":"Glossary","snippet":"The combination of microphones, audio mixers, signal processors, power amplifiers, and loudspeakers that is used to electronically amplify and distribute sound.","tags":["Acoustics","Audio","Signal Processing"],"text":"The combination of microphones, audio mixers, signal processors, power amplifiers, and loudspeakers that is used to electronically amplify and distribute sound."},{"title":"SSM (source-specific multicast)","url":"https://sane-av.github.io/glossary/?search=source-specific%20multicast","type":"Glossary","snippet":"In data streaming SSM allows clients to specify the sources from which they will accept content. This has the dual benefits of reducing demands on the network while improving network security.","tags":["Networking"],"text":"In data streaming SSM allows clients to specify the sources from which they will accept content. This has the dual benefits of reducing demands on the network while improving network security."},{"title":"specification","url":"https://sane-av.github.io/glossary/?search=specification","type":"Glossary","snippet":"A written, precise description of the design criteria for a device or a piece of work. Specifications define the level of qualitative and/or quantitative parameters to be met and the criteria for their acceptance. All specifications must be formulated in terms that are specific, measurable, verifiable, and unambiguous.","tags":["General"],"text":"A written, precise description of the design criteria for a device or a piece of work. Specifications define the level of qualitative and/or quantitative parameters to be met and the criteria for their acceptance. All specifications must be formulated in terms that are specific, measurable, verifiable, and unambiguous."},{"title":"specular reflection","url":"https://sane-av.github.io/glossary/?search=specular%20reflection","type":"Glossary","snippet":"The mirror-like reflection of electromagnetic radiation, in which most of the radiation is reflected in a single direction.","tags":["General"],"text":"The mirror-like reflection of electromagnetic radiation, in which most of the radiation is reflected in a single direction."},{"title":"speech privacy system","url":"https://sane-av.github.io/glossary/?search=speech%20privacy%20system","type":"Glossary","snippet":"A sound system that adds background noise to an environment to raise the hearing threshold and thus make it more difficult to hear low-level sounds such as traffic noise, machinery, and distant human speech. Used to assist with speech privacy in open environments.","tags":["Acoustics","Electrical"],"text":"A sound system that adds background noise to an environment to raise the hearing threshold and thus make it more difficult to hear low-level sounds such as traffic noise, machinery, and distant human speech. Used to assist with speech privacy in open environments."},{"title":"speech-reinforcement system","url":"https://sane-av.github.io/glossary/?search=speech-reinforcement%20system","type":"Glossary","snippet":"An audio system that reinforces or amplifies a presenter’s voice.","tags":["Audio"],"text":"An audio system that reinforces or amplifies a presenter’s voice."},{"title":"splitter","url":"https://sane-av.github.io/glossary/?search=splitter","type":"Glossary","snippet":"An electronic device that splits a signal to route it to different devices.","tags":["Signal Processing"],"text":"An electronic device that splits a signal to route it to different devices."},{"title":"spot photometer","url":"https://sane-av.github.io/glossary/?search=spot%20photometer","type":"Glossary","snippet":"Also known as a spot meter. A type of photometer used to measure illuminance over a narrow angle.","tags":["Video","Lighting"],"text":"Also known as a spot meter. A type of photometer used to measure illuminance over a narrow angle."},{"title":"standing wave","url":"https://sane-av.github.io/glossary/?search=standing%20wave","type":"Glossary","snippet":"The phenomenon that occurs between parallel reflecting surfaces (e.g., walls in a room or a loudspeaker cabinet) where the distance between those parallel surfaces equals one-half wavelength of a wave (and the harmonics thereof). The wave is thus reflected on itself out of phase, creating an interference pattern with location-specific areas of maximum and minimum amplitude.","tags":["Acoustics","Audio","Electrical"],"text":"The phenomenon that occurs between parallel reflecting surfaces (e.g., walls in a room or a loudspeaker cabinet) where the distance between those parallel surfaces equals one-half wavelength of a wave (and the harmonics thereof). The wave is thus reflected on itself out of phase, creating an interference pattern with location-specific areas of maximum and minimum amplitude."},{"title":"star topology","url":"https://sane-av.github.io/glossary/?search=star%20topology","type":"Glossary","snippet":"A network topology where all network devices are connected to a central network device, usually a switch or bridge.","tags":["Networking"],"text":"A network topology where all network devices are connected to a central network device, usually a switch or bridge."},{"title":"static IP address","url":"https://sane-av.github.io/glossary/?search=static%20IP%20address","type":"Glossary","snippet":"A permanently assigned IP address.","tags":["Networking"],"text":"A permanently assigned IP address."},{"title":"stereophonic","url":"https://sane-av.github.io/glossary/?search=stereophonic","type":"Glossary","snippet":"An audio reproduction system where multiple outputs are designed to create the illusion of sound perspective.","tags":["Audio"],"text":"An audio reproduction system where multiple outputs are designed to create the illusion of sound perspective."},{"title":"streaming video/streaming audio","url":"https://sane-av.github.io/glossary/?search=streaming%20video%2Fstreaming%20audio","type":"Glossary","snippet":"Sequence of moving images or sounds sent in a continuous stream over the Internet and displayed by the viewer as they arrive. With streaming video or audio, a web user does not need to wait to download a large file before seeing the video or hearing the sound.","tags":["Audio","Video","Networking"],"text":"Sequence of moving images or sounds sent in a continuous stream over the Internet and displayed by the viewer as they arrive. With streaming video or audio, a web user does not need to wait to download a large file before seeing the video or hearing the sound."},{"title":"subnet","url":"https://sane-av.github.io/glossary/?search=subnet","type":"Glossary","snippet":"A logical group of hosts within a local area network (LAN). A LAN may consist of a single subnet, or it may be divided into several subnets. Additional subnets may be created by modifying the subnet mask on the network devices and hosts.","tags":["Networking"],"text":"A logical group of hosts within a local area network (LAN). A LAN may consist of a single subnet, or it may be divided into several subnets. Additional subnets may be created by modifying the subnet mask on the network devices and hosts."},{"title":"subnet mask","url":"https://sane-av.github.io/glossary/?search=subnet%20mask","type":"Glossary","snippet":"A number that identifies which part of an IP address corresponds to the network address and which corresponds to a host address on that network. In CIDR notation the mask is represented by a slash (/), followed by the number of bits as a decimal number (e.g., /24). In dotted-decimal notation the mask is represented by a dotted-decimal representation of the bit pattern for network and host address bits, where bits equal to 1 indicate that the corresponding bits in the IP address identify the network address, and bits equal to 0 identify the host address (e.g., 255.255.255.0, which is equivalent to /24). IP addresses with the same network identifier bits are on the same subnet.","tags":["Networking"],"text":"A number that identifies which part of an IP address corresponds to the network address and which corresponds to a host address on that network. In CIDR notation the mask is represented by a slash (/), followed by the number of bits as a decimal number (e.g., /24). In dotted-decimal notation the mask is represented by a dotted-decimal representation of the bit pattern for network and host address bits, where bits equal to 1 indicate that the corresponding bits in the IP address identify the network address, and bits equal to 0 identify the host address (e.g., 255.255.255.0, which is equivalent to /24). IP addresses with the same network identifier bits are on the same subnet."},{"title":"subwoofer","url":"https://sane-av.github.io/glossary/?search=subwoofer","type":"Glossary","snippet":"A loudspeaker that reproduces lower frequencies, typically 20Hz to 100Hz.","tags":["Audio"],"text":"A loudspeaker that reproduces lower frequencies, typically 20Hz to 100Hz."},{"title":"supercardioid polar pattern","url":"https://sane-av.github.io/glossary/?search=supercardioid%20polar%20pattern","type":"Glossary","snippet":"The exaggerated heart shape of the area where a highly directional microphone is most sensitive to sound.","tags":["Audio"],"text":"The exaggerated heart shape of the area where a highly directional microphone is most sensitive to sound."},{"title":"surface-mount microphone","url":"https://sane-av.github.io/glossary/?search=surface-mount%20microphone","type":"Glossary","snippet":"Also called a boundary microphone or pressure zone microphone. A microphone designed to be mounted directly against a hard boundary or surface, such as a conference table, a stage floor, or a wall, to pick up sound.","tags":["Audio","Systems & Control"],"text":"Also called a boundary microphone or pressure zone microphone. A microphone designed to be mounted directly against a hard boundary or surface, such as a conference table, a stage floor, or a wall, to pick up sound."},{"title":"surround-sound system","url":"https://sane-av.github.io/glossary/?search=surround-sound%20system","type":"Glossary","snippet":"An audio system that uses multiple channels to produce an acoustic experience where the sound appears to surround listeners.","tags":["Acoustics","Audio"],"text":"An audio system that uses multiple channels to produce an acoustic experience where the sound appears to surround listeners."},{"title":"switch-mode power supply","url":"https://sane-av.github.io/glossary/?search=switch-mode%20power%20supply","type":"Glossary","snippet":"A type of DC power supply that uses a switching regulator to control the output voltage.","tags":["Electrical"],"text":"A type of DC power supply that uses a switching regulator to control the output voltage."},{"title":"switcher","url":"https://sane-av.github.io/glossary/?search=switcher","type":"Glossary","snippet":"A device used to select one of several available signals.","tags":["General"],"text":"A device used to select one of several available signals."},{"title":"sync","url":"https://sane-av.github.io/glossary/?search=sync","type":"Glossary","snippet":"Synchronization. The timing information used to coordinate signals and events.","tags":["General"],"text":"Synchronization. The timing information used to coordinate signals and events."},{"title":"system","url":"https://sane-av.github.io/glossary/?search=system","type":"Glossary","snippet":"In the AV industry, a compilation of multiple individual AV components and subsystems interconnected to achieve a communication goal.","tags":["General"],"text":"In the AV industry, a compilation of multiple individual AV components and subsystems interconnected to achieve a communication goal."},{"title":"system black","url":"https://sane-av.github.io/glossary/?search=system%20black","type":"Glossary","snippet":"The lowest level of luminance a video system is capable of producing for its operating conditions.","tags":["Video"],"text":"The lowest level of luminance a video system is capable of producing for its operating conditions."},{"title":"system ground","url":"https://sane-av.github.io/glossary/?search=system%20ground","type":"Glossary","snippet":"The point at which the safety earth/ground for an electrical system is connected to the earth, usually through a highly conductive earthing/grounding spike driven into the ground (planet Earth).","tags":["Electrical"],"text":"The point at which the safety earth/ground for an electrical system is connected to the earth, usually through a highly conductive earthing/grounding spike driven into the ground (planet Earth)."},{"title":"tap","url":"https://sane-av.github.io/glossary/?search=tap","type":"Glossary","snippet":"A connection to a transformer winding that allows you to select a different voltage from the transformer.","tags":["Electrical"],"text":"A connection to a transformer winding that allows you to select a different voltage from the transformer."},{"title":"task lighting","url":"https://sane-av.github.io/glossary/?search=task%20lighting","type":"Glossary","snippet":"Lighting directed to a specific surface or area that provides illumination for visual tasks.","tags":["Lighting"],"text":"Lighting directed to a specific surface or area that provides illumination for visual tasks."},{"title":"tensile strength","url":"https://sane-av.github.io/glossary/?search=tensile%20strength","type":"Glossary","snippet":"The maximum stress that a material can withstand before deforming or stretching while being pulled.","tags":["Cabling"],"text":"The maximum stress that a material can withstand before deforming or stretching while being pulled."},{"title":"threat","url":"https://sane-av.github.io/glossary/?search=threat","type":"Glossary","snippet":"An individual, group, circumstance, or event that may exploit vulnerabilities in AV or information systems to adversely affect them.","tags":["Security"],"text":"An individual, group, circumstance, or event that may exploit vulnerabilities in AV or information systems to adversely affect them."},{"title":"threat/vulnerability model","url":"https://sane-av.github.io/glossary/?search=threat%2Fvulnerability%20model","type":"Glossary","snippet":"A listing of AV services and devices that may contain vulnerabilities and therefore could be threatened with exploitation. The assessment should also account for threat agents who may attempt to compromise these systems.","tags":["Security"],"text":"A listing of AV services and devices that may contain vulnerabilities and therefore could be threatened with exploitation. The assessment should also account for threat agents who may attempt to compromise these systems."},{"title":"three-phase power","url":"https://sane-av.github.io/glossary/?search=three-phase%20power","type":"Glossary","snippet":"Alternating-current electrical power supplied by three current-carrying conductors, each carrying an AC voltage with a phase offset of 120 degrees from one another. A fourth conductor, a neutral, is used as the return conductor. This type of supply is used for commercial and industrial applications.","tags":["Electrical"],"text":"Alternating-current electrical power supplied by three current-carrying conductors, each carrying an AC voltage with a phase offset of 120 degrees from one another. A fourth conductor, a neutral, is used as the return conductor. This type of supply is used for commercial and industrial applications."},{"title":"threshold","url":"https://sane-av.github.io/glossary/?search=threshold","type":"Glossary","snippet":"The point at which a function or effect becomes active.","tags":["General"],"text":"The point at which a function or effect becomes active."},{"title":"throw distance","url":"https://sane-av.github.io/glossary/?search=throw%20distance","type":"Glossary","snippet":"The distance between a light source, such as a projector or luminaire, and a focusing surface, such as a stage or a screen.","tags":["Video","Lighting"],"text":"The distance between a light source, such as a projector or luminaire, and a focusing surface, such as a stage or a screen."},{"title":"TR (Throw Ratio)","url":"https://sane-av.github.io/glossary/throw-ratio/","type":"Glossary","snippet":"","tags":["Video"],"text":"**Throw ratio** is the relationship between a projector's **throw distance** (the distance from\nthe lens to the screen) and the **screen width**. It is expressed as a dimensionless ratio.\n\n**Throw Ratio = Throw Distance / Screen Width**\n\n## Examples\n\nIf a projector is placed 4.5 m from a 3.0 m wide screen:\n\n**TR = 4.5 / 3.0 = 1.5**\n\nThis lens has a throw ratio of **1.5:1** (or simply 1.5).\n\n## Solving for Any Variable\n\n| Unknown | Formula |\n|---------|---------|\n| Throw distance | `Distance = TR × Screen Width` |\n| Screen width | `Width = Distance ÷ TR` |\n| Throw ratio | `TR = Distance ÷ Width` |\n\nUse the [SANE Throw Ratio Calculator](/tools/throw-ratio) to solve interactively.\n\n## Zoom Lenses\n\nZoom lenses specify a **range** of throw ratios, e.g. 1.2–1.8. The minimum ratio produces\nthe largest image at a given distance; the maximum ratio produces the smallest.\n\n## Typical Throw Ratio Ranges\n\n| Lens Category | Typical Range |\n|---|---|\n| Ultra-short throw (UST) | 0.1 – 0.4 |\n| Short throw | 0.4 – 1.0 |\n| Standard | 1.0 – 2.5 |\n| Long throw | 2.5 – 8.0+ |\n\n## Notes for Installation\n\n- Always verify the exact throw ratio from the manufacturer's specification sheet for the\n  lens you are using. Published values are nominal; actual image size may vary slightly.\n- Account for lens shift range if the projector will not be centered on the screen axis.\n- For screens taller than wide (portrait), the throw ratio formula still uses screen **width**."},{"title":"Thunderbolt","url":"https://sane-av.github.io/glossary/?search=Thunderbolt","type":"Glossary","snippet":"Interface technology that transfers audio, video, power, and data over one cable in two directions. Thunderbolt versions 1 and 2 use the same connector as Mini DisplayPort (MDP), while Thunderbolt versions 3 and 4 use USB Type-C.","tags":["Audio","Video","Networking","Cabling","Signal Processing"],"text":"Interface technology that transfers audio, video, power, and data over one cable in two directions. Thunderbolt versions 1 and 2 use the same connector as Mini DisplayPort (MDP), while Thunderbolt versions 3 and 4 use USB Type-C."},{"title":"time code","url":"https://sane-av.github.io/glossary/?search=time%20code","type":"Glossary","snippet":"A sequence of numeric codes generated at fixed intervals to provide a time synchronization signal. The Society of Motion Picture and Television Engineers (SMPTE) time code used throughout the AV and production industries uses an eight-digit data scheme, representing the hour, minute, second, and frame number for each frame of a video sequence. The SMPTE time code is encoded in a wide variety of formats, including being embedded in audio, video, and data streams.","tags":["Audio","Video","Signal Processing","Standards"],"text":"A sequence of numeric codes generated at fixed intervals to provide a time synchronization signal. The Society of Motion Picture and Television Engineers (SMPTE) time code used throughout the AV and production industries uses an eight-digit data scheme, representing the hour, minute, second, and frame number for each frame of a video sequence. The SMPTE time code is encoded in a wide variety of formats, including being embedded in audio, video, and data streams."},{"title":"time domain","url":"https://sane-av.github.io/glossary/?search=time%20domain","type":"Glossary","snippet":"A view of a signal as amplitude versus time. The display on a time-based oscilloscope shows the input signal in the time domain.","tags":["Video"],"text":"A view of a signal as amplitude versus time. The display on a time-based oscilloscope shows the input signal in the time domain."},{"title":"TSN (Time-Sensitive Networking)","url":"https://sane-av.github.io/glossary/?search=Time-Sensitive%20Networking","type":"Glossary","snippet":"The IEEE working group overseeing the Audio Video Bridging standard has been renamed Time-Sensitive Networking to reflect the standard’s applicability to communication among different types of devices, such as network sensors. Also known as Audio Video Bridging (AVB).","tags":["Audio","Video","Standards"],"text":"The IEEE working group overseeing the Audio Video Bridging standard has been renamed Time-Sensitive Networking to reflect the standard’s applicability to communication among different types of devices, such as network sensors. Also known as Audio Video Bridging (AVB)."},{"title":"transduction","url":"https://sane-av.github.io/glossary/?search=transduction","type":"Glossary","snippet":"The process by which one form of energy is changed into another.","tags":["Audio"],"text":"The process by which one form of energy is changed into another."},{"title":"transformer","url":"https://sane-av.github.io/glossary/?search=transformer","type":"Glossary","snippet":"A passive electrical device that electromagnetically transfers energy between two AC circuits. Commonly constructed of at least two electrically isolated induction coils sharing a common core.","tags":["Electrical"],"text":"A passive electrical device that electromagnetically transfers energy between two AC circuits. Commonly constructed of at least two electrically isolated induction coils sharing a common core."},{"title":"transient disturbance","url":"https://sane-av.github.io/glossary/?search=transient%20disturbance","type":"Glossary","snippet":"A momentary variation in a signal, such as a surge, spike, sag, dropout, or spurious noise.","tags":["Signal Processing"],"text":"A momentary variation in a signal, such as a surge, spike, sag, dropout, or spurious noise."},{"title":"TMDS (transition-minimized differential signaling)","url":"https://sane-av.github.io/glossary/?search=transition-minimized%20differential%20signaling","type":"Glossary","snippet":"A technology for transmitting high-speed serial data. The signaling method used in the HDMI and DVI interfaces.","tags":["Video"],"text":"A technology for transmitting high-speed serial data. The signaling method used in the HDMI and DVI interfaces."},{"title":"transmission","url":"https://sane-av.github.io/glossary/?search=transmission","type":"Glossary","snippet":"The passage of a wave through a medium. Examples include the transmission of soundwaves through air and the transmission of electromagnetic waves through space.","tags":["General"],"text":"The passage of a wave through a medium. Examples include the transmission of soundwaves through air and the transmission of electromagnetic waves through space."},{"title":"TCP (Transmission Control Protocol)","url":"https://sane-av.github.io/glossary/?search=Transmission%20Control%20Protocol","type":"Glossary","snippet":"A connection-oriented, reliable Transport-layer (layer 4) protocol. TCP transport uses two-way communication to provide guaranteed delivery of information to a remote host. It is connection-oriented, meaning it creates and verifies a connection with the remote host before sending it any data. It is reliable because it tracks each packet and ensures that it arrives intact. TCP is the most common transport protocol for sending data across the Internet.","tags":["Networking"],"text":"A connection-oriented, reliable Transport-layer (layer 4) protocol. TCP transport uses two-way communication to provide guaranteed delivery of information to a remote host. It is connection-oriented, meaning it creates and verifies a connection with the remote host before sending it any data. It is reliable because it tracks each packet and ensures that it arrives intact. TCP is the most common transport protocol for sending data across the Internet."},{"title":"transmission loss","url":"https://sane-av.github.io/glossary/?search=transmission%20loss","type":"Glossary","snippet":"The attenuation that occurs as a signal moves through a medium. Usually expressed in decibels.","tags":["Signal Processing"],"text":"The attenuation that occurs as a signal moves through a medium. Usually expressed in decibels."},{"title":"transmissive technology","url":"https://sane-av.github.io/glossary/?search=transmissive%20technology","type":"Glossary","snippet":"Any display device that creates images by controlling the passage of light.","tags":["Video"],"text":"Any display device that creates images by controlling the passage of light."},{"title":"triac","url":"https://sane-av.github.io/glossary/?search=triac","type":"Glossary","snippet":"A bi-directional semiconductor device from the thyristor power-switching family that can switch both half-cycles of an AC current. The equivalent of a pair of SCRs in inverse parallel. The switching device used in many commercial phase-control dimmers.","tags":["Electrical","Lighting"],"text":"A bi-directional semiconductor device from the thyristor power-switching family that can switch both half-cycles of an AC current. The equivalent of a pair of SCRs in inverse parallel. The switching device used in many commercial phase-control dimmers."},{"title":"tweeter","url":"https://sane-av.github.io/glossary/?search=tweeter","type":"Glossary","snippet":"A loudspeaker that is specifically designed to reproduce frequencies above 3kHz.","tags":["Audio"],"text":"A loudspeaker that is specifically designed to reproduce frequencies above 3kHz."},{"title":"twisted-pair","url":"https://sane-av.github.io/glossary/?search=twisted-pair","type":"Glossary","snippet":"A pair of wires that are twisted around each other to facilitate common-mode noise rejection.","tags":["Cabling"],"text":"A pair of wires that are twisted around each other to facilitate common-mode noise rejection."},{"title":"two-factor authentication","url":"https://sane-av.github.io/glossary/?search=two-factor%20authentication","type":"Glossary","snippet":"An authentication method that combines two different validation methods to address a single authentication request.","tags":["Security"],"text":"An authentication method that combines two different validation methods to address a single authentication request."},{"title":"two-way/three-way loudspeaker","url":"https://sane-av.github.io/glossary/?search=two-way%2Fthree-way%20loudspeaker","type":"Glossary","snippet":"A loudspeaker enclosure containing two or three separate loudspeakers, each designed to optimally reproduce a portion of the audio spectrum. The multispeaker enclosure is intended to cover the entire spectrum from a single cabinet. Each loudspeaker may be fed from a separate amplifier (bi-amplification or tri-amplification), or the entire enclosure may be fed from a single amplifier with an internal crossover filter network used to send the optimal frequency band to each of the loudspeakers.","tags":["Audio","Signal Processing"],"text":"A loudspeaker enclosure containing two or three separate loudspeakers, each designed to optimally reproduce a portion of the audio spectrum. The multispeaker enclosure is intended to cover the entire spectrum from a single cabinet. Each loudspeaker may be fed from a separate amplifier (bi-amplification or tri-amplification), or the entire enclosure may be fed from a single amplifier with an internal crossover filter network used to send the optimal frequency band to each of the loudspeakers."},{"title":"UHD ecosystem","url":"https://sane-av.github.io/glossary/?search=UHD%20ecosystem","type":"Glossary","snippet":"The video cameras, recorders, servers, media players, displays, distribution, processing, and networking technologies used for recording, editing, producing, delivering, and displaying ultra-high-definition video.","tags":["Video"],"text":"The video cameras, recorders, servers, media players, displays, distribution, processing, and networking technologies used for recording, editing, producing, delivering, and displaying ultra-high-definition video."},{"title":"ultra-high-definition (UHD or ultra HD)","url":"https://sane-av.github.io/glossary/?search=ultra-high-definition%20(UHD%20or%20ultra%20HD)","type":"Glossary","snippet":"A term used to describe video formats with a minimum resolution of 3840×2160 pixels in a 16×9 or wider aspect ratio.","tags":["Video"],"text":"A term used to describe video formats with a minimum resolution of 3840×2160 pixels in a 16×9 or wider aspect ratio."},{"title":"UWB (ultra-wideband)","url":"https://sane-av.github.io/glossary/?search=ultra-wideband","type":"Glossary","snippet":"UWB is a low-power communications protocol that transmits an extremely wide bandwidth (500+MHz) signal using time modulation to encode the data. Its signals are highly immune to interference from other RF systems, yet produce very little interference with them. UWB can detect the distance between the transmitter and receiver, enabling proximity detection and triggering.","tags":["Lighting"],"text":"UWB is a low-power communications protocol that transmits an extremely wide bandwidth (500+MHz) signal using time modulation to encode the data. Its signals are highly immune to interference from other RF systems, yet produce very little interference with them. UWB can detect the distance between the transmitter and receiver, enabling proximity detection and triggering."},{"title":"unbalanced circuit","url":"https://sane-av.github.io/glossary/?search=unbalanced%20circuit","type":"Glossary","snippet":"A circuit in which one conductor carries the signal and another conductor carries the return. The return conductor is often the cable shield or drain wire and is a low-impedance connection connected to the signal ground. As the impedances of the two conductors are quite different, they are unbalanced with respect to one another.","tags":["Electrical","Cabling","Signal Processing"],"text":"A circuit in which one conductor carries the signal and another conductor carries the return. The return conductor is often the cable shield or drain wire and is a low-impedance connection connected to the signal ground. As the impedances of the two conductors are quite different, they are unbalanced with respect to one another."},{"title":"unicast streaming","url":"https://sane-av.github.io/glossary/?search=unicast%20streaming","type":"Glossary","snippet":"A one-to-one connection between the streaming server sending out the data and client devices listening to the stream. Each client has a direct relationship with the server. Since the server is sending out a separate stream for each client, unicast streaming of media to three clients at 100kbps actually uses 300kbps of bandwidth. IP unicast streams may use either UDP or TCP transport, although TCP transport will inevitably require some buffering.","tags":["Networking"],"text":"A one-to-one connection between the streaming server sending out the data and client devices listening to the stream. Each client has a direct relationship with the server. Since the server is sending out a separate stream for each client, unicast streaming of media to three clients at 100kbps actually uses 300kbps of bandwidth. IP unicast streams may use either UDP or TCP transport, although TCP transport will inevitably require some buffering."},{"title":"unity gain","url":"https://sane-av.github.io/glossary/?search=unity%20gain","type":"Glossary","snippet":"Derived from the number 1; refers to no change in gain.","tags":["Audio"],"text":"Derived from the number 1; refers to no change in gain."},{"title":"USB (Universal Serial Bus)","url":"https://sane-av.github.io/glossary/?search=Universal%20Serial%20Bus","type":"Glossary","snippet":"A standard for connecting, communicating, and supplying power between electronic devices. Version 3.2 of USB is capable of communicating at 20Gbps and can utilize a USB Type-C (USB-C) connector, which supports DisplayPort, HDMI, VGA, power, USB 2.0, and USB3.2. USB4 includes handling the Thunderbolt protocol. USB4 version 1 communicates at up to 40Gbps, while version 2 communicates at up to 80Gbps in symmetric mode, and at up to 120/40Gbps in asymmetric mode.","tags":["Video","Networking","Electrical","Cabling","Signal Processing"],"text":"A standard for connecting, communicating, and supplying power between electronic devices. Version 3.2 of USB is capable of communicating at 20Gbps and can utilize a USB Type-C (USB-C) connector, which supports DisplayPort, HDMI, VGA, power, USB 2.0, and USB3.2. USB4 includes handling the Thunderbolt protocol. USB4 version 1 communicates at up to 40Gbps, while version 2 communicates at up to 80Gbps in symmetric mode, and at up to 120/40Gbps in asymmetric mode."},{"title":"unshielded twisted-pair cable","url":"https://sane-av.github.io/glossary/?search=unshielded%20twisted-pair%20cable","type":"Glossary","snippet":"Typically used for data transfer, UTP cable contains multiple two-conductor pairs of similar impedance, twisted at regular intervals, employing no external shielding.","tags":["Electrical","Cabling"],"text":"Typically used for data transfer, UTP cable contains multiple two-conductor pairs of similar impedance, twisted at regular intervals, employing no external shielding."},{"title":"UX","url":"https://sane-av.github.io/glossary/?search=UX","type":"Glossary","snippet":"User experience. How a user interacts with and experiences a system or an object.","tags":["Systems & Control"],"text":"User experience. How a user interacts with and experiences a system or an object."},{"title":"vectorscope","url":"https://sane-av.github.io/glossary/?search=vectorscope","type":"Glossary","snippet":"A specialized oscilloscope-type display used in video systems to display and measure chrominance accuracy and levels. A vectorscope mode may be included in video waveform monitoring systems.","tags":["Video"],"text":"A specialized oscilloscope-type display used in video systems to display and measure chrominance accuracy and levels. A vectorscope mode may be included in video waveform monitoring systems."},{"title":"vertical scan rate","url":"https://sane-av.github.io/glossary/?search=vertical%20scan%20rate","type":"Glossary","snippet":"The number of complete fields a device draws in a second. This may also be called the frame rate, vertical sync rate, or refresh rate. The vertical scan rate is measured in hertz (Hz).","tags":["Video"],"text":"The number of complete fields a device draws in a second. This may also be called the frame rate, vertical sync rate, or refresh rate. The vertical scan rate is measured in hertz (Hz)."},{"title":"videowall","url":"https://sane-av.github.io/glossary/?search=videowall","type":"Glossary","snippet":"A video display composed of a matrix of smaller video displays linked to display a contiguous image.","tags":["Video"],"text":"A video display composed of a matrix of smaller video displays linked to display a contiguous image."},{"title":"viewing angle","url":"https://sane-av.github.io/glossary/?search=viewing%20angle","type":"Glossary","snippet":"The angle at which a viewer is located in reference to the center axis of a display.","tags":["Video"],"text":"The angle at which a viewer is located in reference to the center axis of a display."},{"title":"viewing area plan","url":"https://sane-av.github.io/glossary/?search=viewing%20area%20plan","type":"Glossary","snippet":"A plan-view drawing of the viewing environment that identifies five viewing locations as defined in the requirements section of the ANSI/INFOCOMM V201.01 Standard Image System Contrast Ratio.","tags":["Video","Standards"],"text":"A plan-view drawing of the viewing environment that identifies five viewing locations as defined in the requirements section of the ANSI/INFOCOMM V201.01 Standard Image System Contrast Ratio."},{"title":"viewing cone","url":"https://sane-av.github.io/glossary/?search=viewing%20cone","type":"Glossary","snippet":"The volume of space containing the audience viewing a display. The term cone is used because there are width, height, and depth to the viewing space, which emanate from the center of the display.","tags":["Audio","Video"],"text":"The volume of space containing the audience viewing a display. The term cone is used because there are width, height, and depth to the viewing space, which emanate from the center of the display."},{"title":"VLAN (virtual local area network)","url":"https://sane-av.github.io/glossary/?search=virtual%20local%20area%20network","type":"Glossary","snippet":"A network created when network devices on separate LAN segments are linked to form a logical group.","tags":["Networking"],"text":"A network created when network devices on separate LAN segments are linked to form a logical group."},{"title":"VPN (virtual private network)","url":"https://sane-av.github.io/glossary/?search=virtual%20private%20network","type":"Glossary","snippet":"A virtual point-to-point private connection established across a network via an encrypted tunneling protocol. VPNs are used for secure remote access, monitoring, troubleshooting, and control.","tags":["Signal Processing","Security"],"text":"A virtual point-to-point private connection established across a network via an encrypted tunneling protocol. VPNs are used for secure remote access, monitoring, troubleshooting, and control."},{"title":"visual acuity","url":"https://sane-av.github.io/glossary/?search=visual%20acuity","type":"Glossary","snippet":"The eye’s ability to discern fine details. There are several different kinds of acuity, including resolution acuity, which is the ability to detect that there are two stimuli, rather than one, in a visual field, and recognition acuity, which is the ability to identify correctly a visual target, such as differentiating between a G and a C.","tags":["Video"],"text":"The eye’s ability to discern fine details. There are several different kinds of acuity, including resolution acuity, which is the ability to detect that there are two stimuli, rather than one, in a visual field, and recognition acuity, which is the ability to identify correctly a visual target, such as differentiating between a G and a C."},{"title":"visual field","url":"https://sane-av.github.io/glossary/?search=visual%20field","type":"Glossary","snippet":"The volume of space that can be seen when a person’s head and eyes are absolutely still. It is specified as an angle, usually in degrees. The visual field of a single eye is termed monocular vision, and the combined visual field where the perceived image from both eyes overlap is called binocular vision.","tags":["Video"],"text":"The volume of space that can be seen when a person’s head and eyes are absolutely still. It is specified as an angle, usually in degrees. The visual field of a single eye is termed monocular vision, and the combined visual field where the perceived image from both eyes overlap is called binocular vision."},{"title":"Voice over Internet Protocol","url":"https://sane-av.github.io/glossary/?search=Voice%20over%20Internet%20Protocol","type":"Glossary","snippet":"A suite of technologies and protocols that allow the transmission of telephone calls and multimedia over Internet Protocol (IP) networks.","tags":["Networking"],"text":"A suite of technologies and protocols that allow the transmission of telephone calls and multimedia over Internet Protocol (IP) networks."},{"title":"volatile memory","url":"https://sane-av.github.io/glossary/?search=volatile%20memory","type":"Glossary","snippet":"Computer memory that loses its data when no longer powered. This type of memory includes the fastaccess, dynamic random-access memory (DRAM) associated with most processor CPUs and GPUs.","tags":["General"],"text":"Computer memory that loses its data when no longer powered. This type of memory includes the fastaccess, dynamic random-access memory (DRAM) associated with most processor CPUs and GPUs."},{"title":"volt","url":"https://sane-av.github.io/glossary/?search=volt","type":"Glossary","snippet":"The basic international unit of potential difference (electromotive force). It is represented by the symbol V.","tags":["General"],"text":"The basic international unit of potential difference (electromotive force). It is represented by the symbol V."},{"title":"voltage","url":"https://sane-av.github.io/glossary/?search=voltage","type":"Glossary","snippet":"The electrical potential difference across a circuit.","tags":["Electrical"],"text":"The electrical potential difference across a circuit."},{"title":"vulnerability","url":"https://sane-av.github.io/glossary/?search=vulnerability","type":"Glossary","snippet":"A weakness in a system, such as an AV or IT service, that may be exploited to adversely affect an organization.","tags":["Security"],"text":"A weakness in a system, such as an AV or IT service, that may be exploited to adversely affect an organization."},{"title":"vulnerability testing","url":"https://sane-av.github.io/glossary/?search=vulnerability%20testing","type":"Glossary","snippet":"An assessment process that involves tools that connect to networked AV or IT systems to determine how they are configured and what vulnerabilities may exist on them.","tags":["Security"],"text":"An assessment process that involves tools that connect to networked AV or IT systems to determine how they are configured and what vulnerabilities may exist on them."},{"title":"watt","url":"https://sane-av.github.io/glossary/?search=watt","type":"Glossary","snippet":"The international unit of power. It is represented by the symbol W.","tags":["Electrical"],"text":"The international unit of power. It is represented by the symbol W."},{"title":"waveform monitor","url":"https://sane-av.github.io/glossary/?search=waveform%20monitor","type":"Glossary","snippet":"An oscilloscope-type monitor used to display the waveforms of signals. A video waveform monitor is a specialized monitor used to display and analyze a video signal’s sync, luminance, and chroma. Some waveform monitors include a vectorscope mode.","tags":["Video"],"text":"An oscilloscope-type monitor used to display the waveforms of signals. A video waveform monitor is a specialized monitor used to display and analyze a video signal’s sync, luminance, and chroma. Some waveform monitors include a vectorscope mode."},{"title":"wavelength","url":"https://sane-av.github.io/glossary/?search=wavelength","type":"Glossary","snippet":"The distance between the corresponding points on two consecutive cycles of a wave. Measured in meters.","tags":["General"],"text":"The distance between the corresponding points on two consecutive cycles of a wave. Measured in meters."},{"title":"wayfinding","url":"https://sane-av.github.io/glossary/?search=wayfinding","type":"Glossary","snippet":"The use of audiovisual guides or signage to assist with navigation to a destination.","tags":["Systems & Control"],"text":"The use of audiovisual guides or signage to assist with navigation to a destination."},{"title":"webcasting","url":"https://sane-av.github.io/glossary/?search=webcasting","type":"Glossary","snippet":"The broadcasting of digital media such as audio or video over the World Wide Web, which audience members can stream live or access on demand.","tags":["Audio","Video","Networking"],"text":"The broadcasting of digital media such as audio or video over the World Wide Web, which audience members can stream live or access on demand."},{"title":"white noise","url":"https://sane-av.github.io/glossary/?search=white%20noise","type":"Glossary","snippet":"A signal with a broad spectrum of random frequencies at the same energy level.","tags":["Audio"],"text":"A signal with a broad spectrum of random frequencies at the same energy level."},{"title":"WAN (wide area network)","url":"https://sane-av.github.io/glossary/?search=wide%20area%20network","type":"Glossary","snippet":"A data communications network that links local area networks (LANs) that are distributed over large geographic areas, such as cities, states, countries, regions, and continents.","tags":["Networking"],"text":"A data communications network that links local area networks (LANs) that are distributed over large geographic areas, such as cities, states, countries, regions, and continents."},{"title":"wire","url":"https://sane-av.github.io/glossary/?search=wire","type":"Glossary","snippet":"A single conductive element intended to carry a current.","tags":["Cabling"],"text":"A single conductive element intended to carry a current."},{"title":"wireless access point","url":"https://sane-av.github.io/glossary/?search=wireless%20access%20point","type":"Glossary","snippet":"A network device that allows other devices to access a wireless network.","tags":["Networking"],"text":"A network device that allows other devices to access a wireless network."},{"title":"WLAN (wireless local area network)","url":"https://sane-av.github.io/glossary/?search=wireless%20local%20area%20network","type":"Glossary","snippet":"A network that shares information by radio frequency (RF) wireless transmission.","tags":["Networking"],"text":"A network that shares information by radio frequency (RF) wireless transmission."},{"title":"woofer","url":"https://sane-av.github.io/glossary/?search=woofer","type":"Glossary","snippet":"A loudspeaker that produces low frequencies, typically 20Hz to 200Hz.","tags":["Audio"],"text":"A loudspeaker that produces low frequencies, typically 20Hz to 200Hz."},{"title":"WBS (work breakdown structure)","url":"https://sane-av.github.io/glossary/?search=work%20breakdown%20structure","type":"Glossary","snippet":"A deliverable-oriented grouping of project elements that will ultimately organize and define the total scope of the project. Each descending level represents an increasingly detailed definition of a project component.","tags":["Project Management"],"text":"A deliverable-oriented grouping of project elements that will ultimately organize and define the total scope of the project. Each descending level represents an increasingly detailed definition of a project component."},{"title":"XLR connector","url":"https://sane-av.github.io/glossary/?search=XLR%20connector","type":"Glossary","snippet":"A latching, low-voltage connector used in professional audiovisual systems. The three-pin version is the standard audio signal cable for the production and AV industries. The four-pin version is widely used for communication headsets, and the five-pin version is the standard connector for the DMX512 digital lighting protocol. Also known as a cannon connector.","tags":["Audio","Electrical","Cabling","Lighting"],"text":"A latching, low-voltage connector used in professional audiovisual systems. The three-pin version is the standard audio signal cable for the production and AV industries. The four-pin version is widely used for communication headsets, and the five-pin version is the standard connector for the DMX512 digital lighting protocol. Also known as a cannon connector."},{"title":"zone","url":"https://sane-av.github.io/glossary/?search=zone","type":"Glossary","snippet":"1. A defined area within a system. 2. In lighting, a zone is a grouping of luminaires (lighting fixtures) that are focused on the same area. 3. In digital signage, a zone is an area where specific content may be placed. 4. In audio, a zone is an area where the same program is delivered.","tags":["Audio","Video","Cabling","Lighting","Systems & Control"],"text":"1. A defined area within a system. 2. In lighting, a zone is a grouping of luminaires (lighting fixtures) that are focused on the same area. 3. In digital signage, a zone is an area where specific content may be placed. 4. In audio, a zone is an area where the same program is delivered."},{"title":"Crown XLi 800","url":"https://sane-av.github.io/equipment/","type":"Equipment","snippet":"Crown XLi 800 - amplifier","tags":["amplifier","audio","commercial","install","amplifier"],"text":"Crown XLi 800 amplifier powerOutput: 2× 300W @ 4Ω, powerOutput8ohm: 2× 200W @ 8Ω, inputImpedance: 20 kΩ balanced, frequency: 20 Hz – 20 kHz (±0.5 dB), snr: > 100 dB, inputSensitivity: 0.775V / 1.4V, dimensions: 2U rackmount Common choice for commercial background music and paging systems."},{"title":"QSC GX5","url":"https://sane-av.github.io/equipment/","type":"Equipment","snippet":"QSC GX5 - amplifier","tags":["amplifier","audio","commercial","touring","amplifier"],"text":"QSC GX5 amplifier powerOutput: 2× 700W @ 4Ω, powerOutput8ohm: 2× 500W @ 8Ω, inputImpedance: 20 kΩ balanced, frequency: 20 Hz – 20 kHz (±0.25 dB), snr: > 100 dB, thd: < 0.1% at 1W, dimensions: 2U rackmount Versatile PA amplifier suitable for live sound and installed systems."},{"title":"Lab.gruppen IPD 1200","url":"https://sane-av.github.io/equipment/","type":"Equipment","snippet":"Lab.gruppen IPD 1200 - amplifier","tags":["amplifier","audio","dante","networked","dsp","amplifier"],"text":"Lab.gruppen IPD 1200 amplifier powerOutput: 2× 600W @ 4Ω, powerOutput8ohm: 2× 400W @ 8Ω, inputImpedance: 20 kΩ balanced, frequency: 20 Hz – 20 kHz, snr: > 108 dB, features: Dante network audio, integrated DSP, dimensions: 1U rackmount Network-enabled amplifier with integrated DSP and Dante audio."},{"title":"Samsung QM55B","url":"https://sane-av.github.io/equipment/","type":"Equipment","snippet":"Samsung QM55B - display","tags":["display","video","commercial","4k","samsung","display"],"text":"Samsung QM55B display screenSize: 55\", resolution: 3840×2160 (4K UHD), brightness: 500 nit, contrastRatio: 1200:1, inputs: HDMI 2.0 ×3, DisplayPort 1.2, USB-C, mounting: VESA 400×400, orientation: Landscape / Portrait, usageHours: 16/7 Commercial-grade display suitable for digital signage and conference rooms."},{"title":"LG 86UH5F","url":"https://sane-av.github.io/equipment/","type":"Equipment","snippet":"LG 86UH5F - display","tags":["display","video","commercial","4k","large-format","display"],"text":"LG 86UH5F display screenSize: 86\", resolution: 3840×2160 (4K UHD), brightness: 400 nit, inputs: HDMI 2.0 ×3, USB ×2, RS-232, mounting: VESA 600×400, orientation: Landscape, usageHours: 24/7 Large format display for lobby and boardroom applications."},{"title":"Epson EB-PU2216B","url":"https://sane-av.github.io/equipment/","type":"Equipment","snippet":"Epson EB-PU2216B - projector","tags":["projector","video","laser","large-venue","wuxga","projector"],"text":"Epson EB-PU2216B projector brightness: 16,000 lumens, resolution: 1920×1200 (WUXGA), technology: 3LCD laser, throwRatio: Various (interchangeable lenses), inputs: HDMI ×2, DVI-D, HDBaseT, lifetime: 20,000 hr (laser), weight: 24 kg High-brightness laser projector for large venues and auditoriums."}]