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This glossary will help explain the numerous terms used within signal distribution.


1080p60 is the common standard for HDTV displays and equipment, allowing resolutions up to 1920 x 1080 with non-interlaced progressive scan, with a frame rate of 60Hz. It is also called “Full HD”. Some cinema formats use 1080p24 or 1080p30, which have the same resolution, but lower frame rates to match film. (back to top)

2K is a high-definition video resolution standard that allows roughly twice the resolution of 1080p signals- up to 2048 x 1080. (back to top)

“3D” describes a variety of technologies used to create realistic three-dimensional or stereoscopic images on a display. 3D displays can be either “active”- requiring viewers to wear special glasses that are electronically synchronized to the display, “passive”- requiring viewers to wear special glasses that use polarizing technology and do not require electronics, or “glasses-free” (Auto-stereoscopic) displays that do not require glasses. HDMI uses several different methods to encode the 3D images into the video signals- “top-and-bottom”, “side-by-side” and “frame-packing”. 3D signals generally require higher bandwidth than 2D signals. (back to top)

Serial Digital Interface is an uncompressed digital standard that is transmitted over a 75 Ohm coax cable, using a type BNC connector. The 3G variation allows for 3 Gbps bandwidth needed for a 1080p signal. Used primarily for Broadcast applications, as it does not support HDCP. (back to top)

4K is a new high-definition video resolution standard allowing about four times the resolution of 1080p signals- up to 4096 x 2160 at 24Hz. Formerly only used for digital projection in theaters, it is becoming a new standard for home theater displays as well. (back to top)

AES/EBU is a digital audio standard created jointly by the Audio Engineering Society and the European Broadcasting Union. It is similar to S/PDIF, but uses XLR connectors rather than RCA connectors and has different signal levels. (back to top)

“Analog Sunset”
“Analog Sunset” refers to video licensing agreements that limit analog video outputs of copy-protected content to 480i Component Video. This means that although Component Video can technically support 1080p 60Hz video, only 480i signals are generally available from Blu-ray players and some DVD players and set-top boxes. Devices that convert HDMI to high-resolution Component Video are legally prohibited. These agreements are forcing many customers to upgrade from analog video systems to HDMI digital video in order to watch Hi-Def content. (back to top)

Audio Return Channel (ARC) is a new HDMI feature that allows audio from a TV display device to be transmitted over the HDMI cable back to the AV receiver. This allows the TV’s internal tuner and/or Network receivers to feed audio to the home theater system, without requiring an additional cable. It also allows the selection of audio from the TV between the home theater system and the TV’s built-in speakers. This does not require a special cable, but it does require support by the AV receiver and any other devices in the signal path. Since it is a reverse-path signal, it requires special treatment in extenders, switchers, and splitters. (back to top)

Aspect Ratio
The aspect ratio of an image is the proportion of its width to its height. HDTV images are generally 16:9, while Standard Definition signals are usually 4:3. For example, the actual image on a 50” (measured diagonally) HDTV should measure about 43.5” wide by 24.5” high. (back to top)

Bandwidth is the data rate measured in bits per second (bps). For example: 1000 million bits per second is 1000 Mbps or 1Gbps. (back to top)

Blu-ray is a recent optical disc format that provides much higher video and audio resolution and capacity than DVD. Although similar in appearance, Blu-ray discs can only be played back on Blu-ray players (although most Blue-ray players can play back DVD’s and CD’s). Blu-ray players offer higher-resolution video and un-compressed multi-channel audio over HDMI, but do not support high-definition analog video output. (back to top)

Category 5 cable, commonly known as Cat-5, is an unshielded twisted pair type cable designed for high signal integrity. CAT-5e is an improved version that supports higher data rates than CAT5 cable, but less than CAT-6A cable. CAT-5 Shielded cable includes a foil shield for better protection from radio-frequency interference (RFI), but the shield does not improve performance. (back to top)

Backwards compatible with CAT-5e, Category 6 cable features more stringent specifications for crosstalk and system noise. CAT-6 provides performance up to 250 MHz. CAT-6A (Augmented) cable is rated up to 500 MHz. CAT-6A+ (Belden 10GX) cable provides performance up to 625 MHz. Shielded CAT-6A cables provide additional RFI immunity for locations where RF interference is an issue. (back to top)

Consumer Electronics Control (CEC) is a serial protocol embedded into HDMI signals to allow devices to communicate over the HDMI cable. Although CEC specifies some standards for commands, it allows for variations in implementation by manufacturers, so devices from one manufacturer may or may not communicate properly with devices from another. Most major consumer electronics manufacturers have branded their own interpretations of CEC, adding to the confusion. Many Gefen HDMI devices pass CEC signals, but do not interpret them. Devices such as splitters and matrix switchers usually do not pass CEC signals, as that would cause erratic responses, since CEC is defined as a one-to-one protocol. (back to top)

Component Video
Component video is an analog video format that uses three coaxial cables to carry a complete video signal- Y, Pb, and Pr. It generally uses three RCA connectors colored green (Y), blue (Pb), and red(Pr). Audio is carried separately, using either a pair of analog cables colored red (Right) and white (Left), or a single S/PDIF digital cable.
Although it is capable of carrying 1080p signals, HDCP rules forbid most newer devices, such as Blu-ray players, from offering resolutions over 480i over component video, as the signals can be easily copied, recorder, or distributed (see “Analog Sunset”). (back to top)

Composite Video
Composite video is an analog video format that contains the entire video signal on a single coaxial cable. It is commonly used for low-definition video formats up to 480i. Higher-resolution video requires S-Video, Component video, VGA, DVI, or HDMI. It uses a single RCA connector, usually colored yellow. Audio is generally carried over a pair of RCA connectors, usually colored red and white. (back to top)

Short form for Display Data Channel: It is a VESA standard for communication between a monitor and a video adapter. The DDC channel also contains the EDID data. Since the communication is in a reverse direction from the actual data signal, many fiber devices cannot support it, unless they contain bi-directional optical transceivers. (back to top)

Digital Display Working Group (DDWG) are the creators of the DVI specification. (back to top)

Deep Color
Deep Color is an HDMI feature that increases the precision of brightness and color information sent to the display. It may use 10, 12, or 16-bit precision values per color (Red, Green, and Blue)- up from 8-bits per color used in older systems. It allows over a billion colors to be specified in an image. Along with x.v.Color, both the range and precision of colors encoded into a video signal can match the abilities of the human eye (see x.v.Color). (back to top)

DisplayPort is a royalty-free digital display connection standardized by the Video Electronics Standards Association (VESA). It is designed to connect a computer to its display monitor, or to a home-theater system. It uses either a DisplayPort connector or a Mini DisplayPort connector. (back to top)

Distribution Amplifier
A device that takes one input and amplifies and transmits the video signal to multiple outputs (also called a Splitter). (back to top)

Dolby® Digital 
This is a digital surround sound technology used in movie theaters and upscale home theater systems that enhances audio. It allows compression of up to 7.1 channels of audio into a 2-channel signal.
Dolby® AC-3 is a method for a compression method for encoding up to 5.1 channels of audio into a digital audio signal using a minimum of bandwidth. Dolby® Digital Plus is an enhanced AC-3 format for encoding up to 7.1 channels of audio at a higher quality into a video stream. Dolby® TrueHD is a 100% lossless (“uncompressed”) audio stream, supporting multiple channels over HDMI. The choices of encoding methods are made when the content is mastered at the studio, so home theater systems need to be able to support those choices, or audio will default to a lower-resolution audio format that the system can support. (back to top)

Digital Theater Systems sound: Discrete 5.1 channel surround system that is similar but not the same as Dolby Digital. Dolby Digital is the DTV standard, but DTS competes with it on DVD and in movie theaters. DTS-HD Master Audio is a “lossless” multi-channel audio encoding method similar to Dolby® TrueHD. It is used on many Blu-ray discs, since it can default to standard DTS on systems that cannot support DTS-HD Master Audio. (back to top)

Dual-link DVI
A version of the DVI (Digital Visual Interface) standard that uses additional cable pairs to increase bandwidth and support higher resolutions Dual-link offers twice the bandwidth of Single-link DVI- up to 3840 x 2400. Dual-link DVI cables are required. (back to top)

Digital Visual Interface: A digital video standard established by the Digital Display Working Group which was designed to carry uncompressed digital video signals to a display. DVI-D is digital only, for both Single-link and Dual-link configurations. DVI-I contains both analog and digital, for single and Dual-link configurations. DVI-A is analog only, and is similar to VGA. Single-link supports 1920 x 1200. HDMI uses a similar format to DVI-D for video, but adds audio and many other features. (back to top)

Extended Display Identification Data: A VESA (Video Electronics Standards Association) standard data structure provided by the monitor or display to the source. Some of the EDID data format includes display monitor ID, model, date of manufacture, serial number, max display size, max resolution, and more. EDID also includes audio data, and can be used to control the format of audio signals transmitted by the source device. EDID’s are generally sent from a display each time it is connected to a source, but many Gefen devices allow the EDID’s to be stored, so there is no delay when sources are disconnected or switched. (back to top)

ELR is Gefen’s trademark for “Extra Long Range” extension devices, which use HDBaseT technology. (back to top)

Electromagnetic Interference (EMI) is disturbances in electrical signals induced through magnetic induction from other nearby electrical signals. EMI can generally be reduced by separating cables containing other signals, or by twisting balanced cable pairs, so the induced signals are cancelled out. Shielding is generally not effective against EMI, unless specialized metallic shields are used (See RFI). (back to top)

Serial Bus Interface standard commonly used for computers and digital video. Commonly available as FireWire 400 (400 Mbit/s) and FireWire 800 (3200 Mbit/s). Formerly a standardized connection on Apple computers, also known as i.LINK and IEEE 1394. (back to top)

FST is a Gefen software implementation for HDMI products, including all matrixes, switchers, splitters, distribution amplifiers, etc. It was created and implemented to improve an inherited lengthy HDMI authentication process based on HDMI and HDCP specifications.
Simply put, FST provides a quicker switch when selecting different audio/video sources. In addition to fast switching, it improves overall audio/video system behavior and performance when more than one HDTV display is used in the system. FST allows users to connect/disconnect and turn on/off HDTV displays without affecting other hi-def sources routed to other HDTV displays in the same system. (back to top)

Full HD
Refers to HDTV resolution of 1080p at 60 Hz (see 1080p60). (back to top)

HDBaseT is a new standard released in 2010 for transmitting HDMI video, audio, Ethernet, control signals, and power over a single CAT-5/CAT-6A cable. It supports Full HD uncompressed video, 100BaseT Ethernet, and control signals including IR, CEC, and RS-232. Up to 100W of power can be extended over HDBaseT, to power remote devices. Gefen’s ELR and PoL devices use HDBaseT technology. (back to top)

High-Bandwidth Digital Content Protection: Created by Intel, HDCP is used with HDTV signals over DVI and HDMI connections. HDCP is embedded into most commercial digital video content, so all transport and display devices must support it in order to display the video. Analog video cannot support HDCP, so most HDCP-encrypted video signals can only be displayed at lower resolutions on analog displays (see Analog Sunset). HDCP “Key System Vectors” (KSV) or “keys” control the number of display devices that can display a single HDCP-encrypted video stream. (back to top)

HDMI specification version released on June 2006 that features increased Single-link bandwidth to 340MHz (10.2Gbps), Deep Color billion color support, Dolby TrueHD and DTS-HD Master Audio lossless audio formats, improved lip sync correction, and broader xvYCC color space support (enables 1.8 times as many colors as existing HDTV signals). The HDMI 1.4 Specification was released in June 2009, and added major enhancements to the HDMI features, including HDMI Ethernet Channel (HEC), Audio Return Channel (ARC), and additional support for 3D and 4K display technologies. It is fully-compatible with all previous HDMI releases. HDMI Licensing, LLC forbids manufacturers from designating Release Numbers in product descriptions, and requires that specific features supported be listed instead; therefore Gefen products list the features, rather than the release version. (back to top)

High Definition Serial Digital Interface: This standard transmits audio and video over a single coaxial cable with a data rate of 1.485 Gbit/s. (back to top)

High-Definition Television. It is the high-resolution subset of the Digital Television (DTV) system. It offers a 16:9 image with twice the horizontal and vertical resolution of our previous system, accompanied by 5.1 channels of digital audio. (back to top)

HDMI Ethernet Channel (HEC) is a new feature that allows a 100BaseT Ethernet connection over an HDMI cable. This eliminates the need for a separate Ethernet connection to each networked device in a home theater system (HD Display, Blu-ray player, AV receiver, media player, set-top box, etc.) from a router or switch, and simplifies wiring and system installation. HEC support requires a new cable design, which is designated as a “High Speed HDMI Cable with Ethernet”. (back to top)

IEEE 1394a
Cabling technology for transferring data to and from digital devices at high speed. Also known as FireWire. (back to top)

Internet Protocol (IP) is a format used to transport digital data over Ethernet. It can support a wide variety of content, including data, video signals, audio signals, telephone signals (VoIP), and control signals. (back to top)

Infrared (IR) signaling is a common method of remotely controlling consumer electronic devices. IR remote controls contain one or more infrared LED’s that flash is a specific pattern, depending on the button pressed. The light beam can be detected up to 100 feet away, and decoded to operate the selected function. IR requires a direct line-of-sight between the remote control LED and the controlled device’s IR receiver.
However, separate IR receivers can be located in a more convenient location to pick up the signal, and transmit it to another IR LED (“emitter”, “blaster”, or “flasher”) that is located near the controlled device’s IR receiver (or “eye”). Some devices can also store a sequence of commands for several different devices (called “macros”), and play them back from a single button press. IR is usually one-way communication from the remote control to the controlled device, so any feedback or confirmation usually relies on the user’s ability to directly see or hear the result. This is acceptable for simple control, but creates difficulties in controlling complex systems. For this reason, more complex systems generally use either RS-232 or IP control, allowing them to confirm proper operation. (back to top)

Short for “keyboard, video, and mouse”. Most current KVM devices use USB technology for keyboard and mouse connections, and can support audio and external memory devices as well. (back to top)

A standard type of optical fiber connector termination. The small form factor LC connector was originally developed by Lucent (“Lucent Connector”) for telecommunications networks. (back to top)

Lip Sync
Lip Sync is an HDMI feature that automatically synchronizes audio and video signals between the display and speaker outputs. (back to top)

Linear Pulse-Code Modulation (LPCM) is a method of encoding up to 8 channels (7.1) of uncompressed audio into a digital video signal. (back to top)

Matrix Switcher
A matrix switcher is a device that allows selection from multiple video and audio sources to multiple outputs (display devices). “True” matrix switchers allow a source to feed multiple displays simultaneously, or for each display to show a different source, although there are devices on the market with significant restrictions on source and/or display selection. (back to top)

Mono-Lok is a proprietary Gefen innovation that provides a secure way to attach HDMI cables to devices that support it, preventing cables from becoming loose or falling out. Most Gefen HDMI devices are compatible with Mono-Lok cables, and many other devices are compatible or may adapted to fit, using hardware provided with each Mono-Lok HDMI cable. (back to top)

Multi-Mode Fiber
Multi-mode fiber is designed for high-bandwidth connections over long distances. It is commonly available in both 62.5/125µ and 50/125µ types, with the 50µ fiber supporting longer cable runs. Multi-mode transmitters generally use an LED or VCSEL laser as the optical source. It can use a variety of connectors, including SC, ST, LC, and MTRJ types.
Fiber offers immunity from Electromagnetic Interference (EMI) and Radio-Frequency Interference (RFI), but does not support power connections. Most fiber devices have an optical transmitter (LED or laser) at one end and a photo-detector at the other, so they only support communications in one direction, although some contain bi-directional optical transceivers. Single-mode fiber supports even longer cables, but is generally more expensive, as it requires a more precise optical source (see Single-Mode Fiber). (back to top)

NTSC is the acronym that stands for “National Television System Committee” and the name of the current analog transmission standard used in the US. (back to top)

Phase Alternating Line (PAL) is the analog television display standard that is used in Europe and certain other parts of the world. (back to top)

A single illuminated point on a display. A 1080p display is 1920 pixels wide and 1080 pixels high, so it has 1920 x 1080= 2,073,600 total pixels (2 Megapixels). The size of each pixel depends on the display size (for a 50” display, each pixel is approximately 0.023” square). (back to top)

Power over Line (PoL) is a Gefen proprietary technology that provides 10W of 5 Volt DC power to the Receiver Unit over the single CAT5 signal cable, and allows the Receiver Unit to power additional Gefen devices. It is based on the HDBaseT Power over Ethernet (PoE) Standards, but is specifically tailored to Gefen’s Hi-Def video products. (back to top)

A device to boost original signals transmitted over long copper cable. For digital signals, this usually means cleaning up timing and delay issues (re-clocking) that have degraded, in addition to amplification. (back to top)

The number of picture elements (“pixels”) the display can support. A higher resolution results in a much sharper and clearer video image. (back to top)

Radio-Frequency Interference (RFI) is disturbance caused by high-frequency coupling of external electrical signals. RFI can usually be minimized by electrical shielding of devices, connectors, and cables (See EMI). (back to top)

EIA “Recommended Standard” 232 is the standard for communications through PC serial ports, and is often used to control and automate devices. RS-232 usually uses a DB-9 connector, although only 3 wires are required. (back to top)

A fiber connector (“Square Connector”) with a snap coupling that is used for most fiber formats. It is available in single or duplex forms. (back to top)

A device that takes an input signal at one resolution and scales it to another resolution. Scalers are generally used to “up-scale”, or convert a low-resolution signal to a higher resolution, but they can also be used to “down-scale” a high-resolution signal so it can be displayed on a lower-resolution display, while still allowing the higher-definition signal to be distributed to other displays that can support it. (back to top)

Standard Definition Television: SDTV sets receive a broadcast signal resolution of 480 interlaced lines (480i), as opposed to HDTV (720p, 1080i, and 1080p). SDTV signals are generally in a 4:3 aspect ratio, while HDTV signals are 16:9 aspect ratio.

Simplay HD
Simplay Labs LLC is an independent testing center that tests HDMI performance and interoperability using the Simplay HD test specifications. The Simplay HD testing specification includes real-world usability plug testing of multiple device types. (back to top)

Single-mode Fiber
Single-mode fiber is designed for high-bandwidth connections over long distances. It is commonly available in both 8/125µ and 9/125µ types. Single-mode fiber supports longer cables than multi-mode fiber, but is generally more expensive, as it requires a more precise laser optical source. It can use LC, SC, ST, MTRJ, and other connectors.
Some devices designed for single-mode fiber can also support multi-mode fiber, but over shorter distances (See Multi-Mode Fiber). (back to top)

Set-Top Box
A “Set-top box” is a generic term for a video receiver, such as a cable, broadband, or satellite receiver, that was originally intended to sit on top of and connect to a TV set (although today’s flat-screen TV’s make this a misnomer). Set-top boxes convert proprietary digital video signals into conventional video (often high-definition) and audio. Since the set-top box tuner replaces the TV set’s built-in tuner, it often requires a separate remote control. (back to top)

An industry term used to describe devices which receive electrical signals and output these signals as video, audio, or both. For example: computer monitors, HDTV, audio receivers. (back to top)

An industry term used to describe devices where the electrical signals are being transmitted from; for example, Blu-Ray players, video game consoles, MP3 players. (back to top)

Synchronized Multimedia Integration Language (SMIL) is a language similar to HTML for describing and developing multimedia presentations. It is often used for digital signage applications. SMIL presentations can be played back on most Gefen Digital Signage players or on a PC using QuickTime or Windows Media Player. (back to top)

Society of Motion Picture and Television Engineers. Based in the United States, the association has over 400 standards, Recommended Practices and Engineering Guidelines for television, motion pictures, digital cinema, audio and medical imaging. (back to top)

SPDIF is a digital interface designed to enable digital equipment to transfer digital information with minimal loss. Acronym for Sony/Philips Digital Interconnect Format. Usually describes a Coaxial connection that uses an RCA (phono) connector. (back to top)

A device that takes one input and splits it to multiple outputs. Also called a “Distribution Amplifier” or “hub”. (back to top)

A type of fiber connector (“Straight Tip”) that uses a round bayonet-type coupling generally used for multi-mode fiber connections. The SC and LC connectors are now more prevalent. (back to top)

S-video (originally called “Super Video” or “S-VHS Video”) is an analog video format that separates a video signal into “luminance” and “chrominance” signals, and transports them over two coaxial cables terminated on a 4-pin mini-DIN connector. It is limited to 480i resolution, does not carry audio, and has generally been replaced by component video, or by digital video such as DVI and HDMI. (back to top)

A device that selects between multiple input sources to one output display. To support multiple displays, a Matrix Switcher is used. (back to top)

TMDS (“Transition-Minimized Differential Signaling”) is a method for transmitting high-speed data over twisted-pair cabling that minimizes interference and allows longer cable runs. TMDS is used to encode the digital video portion of an HDMI signal. Other pairs are used for DDC and control signaling (see DDC). (back to top)

Toshiba Optical Link is commonly used to refer to optical digital audio ports and cables (TOSLINK technically also uses S/PDIF format, but S/PDIF usually refers to the Coaxial connections). (back to top)

Universal Serial Bus is an industry standard for high-speed serial connections between computers and other electronic devices. USB 1.1 supports up to 12 Megabits per second (12 Mbps). USB 2.0 offers speeds up to 480 Mbps, using the same physical connector. USB 3.0, released in 2010, supports up to 5 Gbps. USB Type A connectors are used for device connections, and USB Type B connectors are used for Host (computer) connections. A Mini-B type is also used- often for power or firmware updates. Most USB sources can provide 5V DC at up to 500ma to power external devices, although some (such as Apple iPad chargers) can provide up to 2A. (back to top)

UWB (Ultra Wide Band)
A wireless transmission technology engineered for high bandwidth and short distances. The information (data) is modulated / demodulated via pulses in the signal. (back to top)

The Video Electronics Standards Association (VESA) is a consortium of manufacturers formed to establish and maintain industry wide standards for video displays and cards.

Video Graphics Array (VGA) is a standard for computer graphics displays, originally implying a resolution of 640x480 pixels, commonly used to describe VESA standard resolutions. Current variations of VGA (SVGA, WXGA, WUXGA, etc.) can resolve up to 1920 x 1200. The term VGA is commonly used to refer to any analog computer display standard. VGA uses a 15-pin HD-15 connector, with 5 coaxial cables for red, green, blue, horizontal sync, and vertical sync signals. DVI-A and DVI-I connections can also be used to support VGA signals. (back to top)

x.v.Color is an HDMI feature that extends the range of colors that a Hi-Def TV can display. It is also known as “xvYCC” or “Extended-gamut color.” X.v.Color allows newer displays to show colors that could not be specified in older systems (see Deep Color). (back to top)


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"The flexible and reliable nature of the new system requires less manpower to operate, and offers more options in terms of the type of content and the resolution of the content that can be distributed."

– Jeffrey Yip Sau Chuen, JD Molecule