AV/IT Glossary—27 Days of #AVabc—I


IoT—The Internet of Things (Iot) refers to the ever-growing network of physical objects that feature an IP address for internet connectivity, and the communication that occurs between these objects and other Internet-enabled devices and systems.


I2C—The name of a port and protocol used in industrial and consumer electronic devices. I2C ports are relatively slow, and therefore are most suitable for generation of the control signal effecting a large system. The advantage of this port system is simplicity and that only a small number of interface lines are needed.

IEEE—The Institute of Electrical and Electronics Engineers.

I/O-Input/Output—Refers to the flow of information or signals (in or out) with respect to a particular device.

IC (integrated circuit)—Many A/V products use ICs for processing and amplifying audio signals; higher-quality units use discrete transistors instead.

ICIA-International Communications Industries Association—A professional A/V, video, and multimedia industry association. www.infocomm.org

ICT-Image Constraint Token—Part of AACS, the Blu-ray Disc digital rights management system, the Image Constraint Token can cause the output of a Blu-ray Disc player to be down-converted to low-resolution video, similar in quality to a DVD. AACS requires that all components in the display chain, from the source to the display device, to be secured through HDCP or DPCP content protection. If the ICT flag is set and the Blu-ray player is connected to a device that does not support HDCP, for example an analog television or video recorder, the player automatically reduces the high-definition video quality to a maximum of 960x540 pixels before outputting it.

ICWK-Internal Computer Wiring Kit—Custom ICWK kits provide interfacing signals for computers and terminals that have no video display output connector.

ID bit termination—Used to identify what type of display device is attached to a computer-video output port. ID bit termination involves connecting specific data lines or “pins” to the electrical ground. ID bit termination assures that the correct video signals will be sent to the display device. A computer checks for ID bits during the power-up self diagnosis, and sets the video output frequency and resolution based on how the ID bits are set. Some computers will not send any video signal if they do not sense any ID bits on boot-up, so no picture will be displayed. ID bits are also called “sense lines.”

IDTV-Improved Definition Television (Enhanced Definition TV)—This standard resembles HDTV* in output quality without the complexity of the HDTV system. The improved picture quality is achieved by extensive processing carried out in the receiver. No different transmission system is needed.

IEC-International Electro-Technical Commission—The body that has responsibility for developing international A/V standards. ICIA cooperates with IEC sub-committee SC-60.

IEC Connector—The standard AC power connector used on power supplies in computers and other electronic equipment. It accommodates a power cord with a connector on both ends.

IEEE-Institute of Electrical and Electronic Engineers—The IEEE is an industry organization that undertakes the development of standards for electronic interfaces, wireless and wired networks, and related technologies. www.ieee.org.

IEEE 1394—Institute of Electrical and Electronics Engineers standard 1394. Also known as FireWire (a trademark of Apple) and i.Link (a trademark of Sony), IEEE 1394 is a serial digital format that handles a wide range of data. IEEE 1394 offers peer-to-peer interface capability, so it does not require computer support.

IEEE 802.11—The Institute for Electrical and Electronics Engineers standard for wireless Ethernet networks. IEEE 802.11 applies to wireless LANs and provides 1 or 2 Mbps transmission in the 2.4 GHz band using either frequency hopping spread spectrum (FHSS) or direct sequence spread spectrum (DSSS).

IEEE 802.11a—An extension to 802.11 up to 54 Mbps in the 5GHz band. IEEE 802.11a has a data transmission rate capability sufficient for the delivery of “live” or full motion standard definition video.

IEEE 802.11b—Often called Wi-Fi, 802.11b is backward compatible with 802.11. IEEE 802.11b has a data transmission rate of 11 Mbps, sufficient for most non-motion data transmission applications.

IEEE 802.11g—Applies to wireless LANs and provides 20+ Mbps in the 2.4 GHz band. This is the most recently approved 802.11 standard and offers wireless transmission over relatively short distances at up to 54 megabits per second (Mbps), compared with the 11 megabits per second of the 802.11b standard. Like 802.11b, 802.11g operates in the 2.4 GHz range.

IEEE 802.11n—Upcoming wireless standard that builds upon 802.11 standards by adding Multiple Input Multiple Output (MIMO) technology. MIMO uses multiple transmitter and receiver antennas to increase the data rate, promising between 100-200 Mbps. 802.11n is expected to be ratified in late 2006 or early 2007.

IEEE 802.3—The Institute for Electrical and Electronics Engineers standard for Ethernet networks.

If Loop—The input and output of the IF circuitry provided by RF* modulator when IF* is being converted (modulated) to RF. The IF loop generated by the RF modulator is accessible externally and can be supplied to other RF modulators. They can also accept IF from another modulator in order to convert it back to RF.

IGMP-Internet Group Management Protocol—Host-to-router signaling protocol for IPv4 to report their multicast group memberships to neighboring routers and determine whether group members are present during IP multicasting. Similarly, multicast routers, such as E-Series routers, use IGMP to discover which of their hosts belong to multicast groups and to determine if group members are present.

IGMP Snooping—IGMP snooping, as implied by the name, is a feature that allows a switch to “listen in” for multicast join requests on a network and deliver to end-point network devices when requested. A switch which supports IGMP snooping will not flood all of its ports with multicast traffic. IGMP snooping is supported in layer 3 switches and some layer 2 switches.

ILA®-Image Light Amplifier—Used in their large screen projectors, a Hughes-JVC device that uses low-intensity images to modulate high-intensity light through a liquid crystal layer.

i.LINK—Sony’s name for their implementation of IEEE1394 (FireWire) impedance Resistance to the flow of an alternating electrical current.

Illuminance—The light density (the luminous flux divided by area) shining onto a surface. This is the specification that measures how bright a screen is lit by a projector or ambient light. The unit is lux. 1 lux = 1 lumen/m2.

IM/Intermodulation—Distortion or noise. An undesired form of distortion generated by a non-linear amplifier carrying several different signals simultaneously.

Image—A reproduction or imitation of a person or thing displayed by any type of visual media.

Image Noise—The random variation of brightness or color information in images produced by the sensor and circuitry of a scanner or digital camera.

Impedance—The opposition or load to a signal, measured in ohms and abbreviated W or Z. In video, typical low impedance circuits (low Z) are 600 ohms or less and high impedance circuits (high Z) may be 10 k ohms or greater. Video termination impedance is 75 ohms.

Impedance Matching—Circuits that generate audio or video signals are designed to work with a certain load (impedance). When connecting devices in a system, it is important that the impedance specifications are adhered to. If the impedance of the load is not matched to that of the source, there could be undesirable results, such as loss or distortion of the original signal, reflections, etc.

IMUX—Inverse multiplexer. A unit that combines multiple low bandwidth digital phone lines into a single high bandwidth call.

Index Matching Gel—A special gel with an index of refraction similar to that of the optical fiber core. It is applied at the fiber endface to minimize loss due to Fresnel reflection in mechanical splices or cleave and crimp connectors.

Index Matching Materials—Materials with an index of refraction similar to that of the optical fiber core. They are applied at the endfaces of adjoining optical fibers to minimize losses due to Fresnel reflection.

Index of Refraction—The ratio of the speed of light in a vacuum to the speed of light in a material. Also known as the refractive index.

Inductor—An electrical component that opposes changes in current flow and stores electrical energy as a magnetic field. Although all wires have inductive properties, an inductor component is usually a coil of wire. Transformers use this same principle.

Inductive Reactance—The opposition to the flow of alternating current by the inductance of a circuit, measured in ohms.

Infocomm—InfoComm is the largest, most exciting event in the United States focused on the pro-AV industry, with more than 950 exhibitors, thousands of products, and 40,000 attendees from 108+ countries. The InfoComm show is your once-a-year opportunity to see the latest audiovisual technology, learn the skills that will advance your career, and grow your professional network.

Infrared (IR)—Light waves just outside the visible spectrum, slightly longer than those visible to the human eye. Infrared light is sometimes filtered out to reduce heat on film or slides.

Infrared Control—A wireless medium of remote control, which sends signals to a device via pulses, transmitted in the infrared light spectrum. Its use is restricted to equipment within line-of-sight or reflections off a wall or ceiling. This is sometimes called “IR remote.”

Injection Laser Diode-ILD—A laser in which the lasing, or stimulated emission of coherent light, occurs at the p-n junction of a semiconductor.

Inline Splice Closure—An enclosure which houses the spliced fiber optic cable and provides cable ports at opposite ends.

Innerduct—A duct, usually non-metallic, that may be placed within cable trays or HVAC ducts, to be used as conduit for installation of fiber optic cables.

Input Sensitivity—The minimum input level signal required to output a specified output level.

Insertion Loss—The loss of optical power as a result of incorporating components such as connectors, couplers, or splices into an optical fiber system.

Inspection Scope—A microscope specifically for inspecting fiber optic connectors.

Insulation—material applied to a conductor that is used to isolate the flow of electric current between conductors and to provide protection to the conductor; also known as the dielectric.

Interactive TV—A TV system which uses the TV/Cable-network for bi-directional communication. Via TV a user may order groceries, watch a selected movie (VOD- Video On Demand) or get the weather forecast.

Interactive Whiteboard—Interactive Whiteboards are an essential tool in business and classroom communications. They are used to display text, data and graphics from a computer or projector onto a large surface or display. Presenters and users can then interact with the image using a pen, stylus, finger or other device.

Interbuilding Backbone—A backbone network that provides communication between buildings, such as on a university or corporate campus, or military installation.

Interconnect—A cable that carries line-level audio signals.

Interface—A device or module that operates as a link between dissimilar modules, usually because those modules cannot communicate directly with each other. An interface may act as a translator or interpreter and could be in the form of hardware and/or software. A computer video interface allows computer-video signals to be used by large screen video displays

Inter-Frame Coding—A compression technique which spans multiple frames of video and eliminates redundant information between frames.

Interlace/Interlacing—A video frame is made up of two fields. Interlacing is the process of scanning the picture onto a video screen whereby the lines of one scanned field fall evenly between the lines of the preceding field. Each video frame is divided into two fields with one field composed of odd numbered horizontal scan lines and the other composed of even numbered horizontal scan lines. Each field is displayed on an alternating basis.

Interlaced Scanning—The scanning process that combines odd and even fields of video to produce a full frame of video signal.

Interleaving—The process of assigning consecutive physical memory addresses alternately between two memory controllers to increase the effective transfer rate.

Intermediate Cross-Connect-IC—A cross-connect, usually a patch panel, used to provide backbone cabling between the MC - Main Cross-Connect and HC - Horizontal Cross-Connect.

Intermediate Distribution Frame-IDF—In telecommunications applications, a metal rack, located in an equipment room or closet, that provides connection between interbuilding cabling and the intrabuilding cabling.

Intermediate Frequency—A frequency to which a signal wave is shifted locally as an intermediate step in transmission or conversion from one frequency to another. In TV transmissions, a video signal is modulated onto a high RF* signal via IF as a temporary stage.

Interpolation—Filling in missing information with a “best-guess” estimate OR a term used in digital video for creation of new pixels by mathematical comparison to the adjacent pixels. It is the opposite of the Decimation* process. This system is often used for DACs* for easing the analog filtering requirements.

Intersymbol Interference-ISI—In fiber optics, the interference between adjacent digital bits in a serial digital stream caused by pulse spreading in an optical fiber. Pulse spreading in an optical fiber due to dispersion in an optical fiber.

Intrabuilding Backbone—The backbone network within a building that provides communications to individual offices and users.

Intra-Frame Coding—A method of video compression that compresses information within a single frame.

Intra-Prediction—Intra-prediction is an advanced compression technique applied in H.264 which takes advantage of the spatial redundancy within a frame to reduce the amount of data required to encode an I-frame.

Intrinsic Losses—Losses due to inherent differences in the characteristics of the optical fibers being spliced.

Inverse Square Law—Law of physics stating that some physical quantity or strength is inversely proportional to the square of the distance from the source of that physical quantity. Applied to light and sound in AV.

In-Wall Speaker—A speaker mounted inside a wall.

IR—Invisible radiation in the part of the electromagnetic spectrum characterized by wavelengths just longer than those of ordinary visible red light and shorter than those of microwaves or radio waves.

Interface—A boundary across which two independent systems meet and act on or communicate with each other. In computer technology, there are several types of interfaces. user interface - the keyboard, mouse, menus of a computer system. The user interface allows the user to communicate with the operating system.

IR Repeater—A pair of devices, called an “IR sensor” and “IR flasher,” that together relay IR commands from a remote control to components hidden from the remote control’s direct line of sight.

IP (Internet Protocol)—Internet Protocol defines addressing methods and structures for datagram encapsulation allowing delivery of packets from a source to a destination based purely on addressing.

IP Address—A numerical label that is assigned to devices in a network, that uses the Internet Protocol. The IP address for the source and destination are included in an IP datagram.

IP Link®—Extron’s high performance IP integration technology specifically engineered to meet the needs of professional A/V environments.

IP Netmask—A 32-bit binary number (12 digit decimal number—xxx.xxx.xxx.xxx) used on subnets (smaller, local networks) to help the router determine which network traffic gets routed internally to local computers and which network traffic goes out on the Internet.

IPv4-Internet Protocol version 4—The legacy version of the Internet Protocol, which is the fundamental protocol on which the Internet is based. It is a connectionless protocol for use on packet-switched Link Layer networks (e.g., Ethernet). It operates on a best effort delivery model, in that it does not guarantee delivery, nor does it assure proper sequencing, or avoid duplicate delivery.

IPv6-Internet Protocol version 6—This new Internet Protocol is designed to replace and enhance the present protocol which is called TCP/ IP, or officially IPv4. IPv6 has 128-bit addressing, auto configuration, new security features and supports real-time communications and multicasting. The primary equipment to apply IPv6 to is routing equipment, not source equipment.

IPX-Internetwork Packet Exchange Protocol—Commonly used over Novell Netware and Microsoft Windows networks.

IR/Infrared—An invisible light, below human eyes’ perceivable spectrum, used for communication between electronic devices and their remote control units. This method is short ranged, effective only at the line of sight. The IR signal may be converted to an electronic signal carried by a wire to a different location where it is reconverted to IR for controlling a remote device.

IR Learning—The ability of a device to receive and store infrared commands for other devices, such as the projector. Each command is assigned to a system operation (such as selecting an input). When an operation is executed, the associated (learned) command is then transmitted through an IR emitter or broadcaster to the projector, where it is executed. For example, if input #3 is S-video, selecting that input also sends a signal to the projector to switch to S-video mode.

IR Library—Sets of infrared commands for video projectors are available at the Extron Web site (www.extron.com).

IRE-Institute of Radio Engineers—Now called IEEE, the Institute of Electrical and Electronic Engineers. Also see "IEEE."

IRE Scale—An oscilloscope scale that applies to composite video levels. Typically, there are 140 IRE units in one volt (1 IRE = 7.14 mV). This makes luma level values easier to communicate. The amplitude of the video signal from blanking (zero volts) to peak white is 0.714286 volts or 100 IRE units. Sync signals extend from blanking to 1.285714 volts/40 IRE units.

ISDN-Integrated Services Digital Network—An international communications standard for sending voice, video, and data digitally over telephone lines. ISDN uses special wires and can transfer at rates of 64,000 bits per second. Another version called B-ISDN uses fiber optics and can transfer at 1.5 megabits per second.

Isolated Ground—A commonly misused term to describe a requirement for a dedicated equipment ground that terminates only at the main panelboard at the service entrance. An equipment grounding method permitted by the National Electrical Code (NEC) for the reduction of electrical noise (electromagnetic interference) on the grounding circuit. Equipment grounding for isolated receptacles and circuits is accomplished via insulated equipment grounding conductors and run with the circuit conductors.

Isolated Grounding Circuit—A circuit that allows an equipment enclosure to be isolated from the raceway containing circuits, supplying only that equipment by one or more listed nonmetallic raceway fittings. The equipment is grounded via an insulated grounding conductor. (See National Electric Code 250.96 (B) for additional information.)

ITS—Information Transport System or Intelligent Traffic System.

ITU-International Telecommunication UnionFormerly known as the CCIR (Comité Consultatif International des Radiocommunications) or International Radio Consultative Committee. A global organization responsible for establishing television standards.

ITU-R BT.601—Formerly known as CCIR 601. A serial digital form of component video developed by the International Telecommunication Union for the digitization of color video signals. ITU-R BT.601 is the digital equivalent to Y, R-Y, B-Y, component analog video, and is transmitted on one coax cable instead of three. It is also called 4:2:2, which refers to the number of samples taken from each of the video channels: for every four samples of the Y (luminance) channel, the two color difference channels, R-Y and B-Y, are sampled twice.

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