AV/IT Glossary—27 Days of #AVabc—G






Gigabit—A unit of information equal to one billion or 10^9 bits. It's commonly used for measuring the amount of data that is transferred in a second between two telecommunication points.  


Gain—(1) A general term for an increase in signal power or voltage produced by an amplifier. The amount of gain is usually expressed in decibels above a reference level. Opposite of attenuation. (2) The amplification of a signal, unit, or system. Expressed in the unit of measurement appropriate to the signal or system. (3) In fiber optics applications, the measurement of back reflections using an OTDR - Optical Time Domain Reflectometer, due to a mismatch in core sizes between adjoining optical fibers.

Gainer—In fiber optics applications, a backscatter measurement condition with an OTDR that indicates a splice loss, due to a mismatch in core size between the two optical fibers. The resulting trace indicates a perceived increase in power, and is therefore known as a “gainer.”

Gamma—The light output of a CRT is not linear with respect to the voltage input. The difference between what you should have and what is actually output is known as gamma.

Gamma Correction—Before being displayed, the linear RGB data must be processed (gamma corrected) to compensate for the gamma of the display.

Gang—Refers to the number of wiring devices that can be installed in an electrical box, (e.g., “two gang” refers to a box that can accommodate two duplex receptacles, “three gang” refers to a box that can accommodate three duplex receptacles, etc).

Granged Fading—When two signals, such as audio and video signals, are concurrently processed, simultaneous fading* is required. This technique is known as ganged fading.

Gateway—A network node equipped for interfacing with another network that uses different protocols. Also can be described as an entrance and exit into a communications network.

GEM—A graphics metafile format, vector based, which was developed by Digital Research™ and is used in DTP and graphics applications.

Generation—The number of duplication steps between a master recording of videotape and a given copy of that master. A second-generation duplication is a copy of a copy of the original master.

Genlock—A technique where the video output of one source, or a specific reference signal, is used to synchronize other television picture sources together. Video sources which are genlocked have vertical sync pulses which are synchronized together.

Ghost—Also called “ghosting,” or “reflections.” A shadowy or weak duplication of the original image. It can be the result of transmission conditions where secondary signals are created and then displayed earlier or later than the original signal. Ghosts can also be the result of burning an image on a screen or by a mirror.

GHz-Gigahertz—One billion cycles per second.

Giga—The prefix abbreviation for billion. (G) One G-Byte = 1 billion bytes.

Global Presets—The Extron matrix switcher output configuration settings that can affect all output connections/ties and can be saved/recalled by simply pressing a button or issuing a Simple Instruction Set (SIS™) command.

GOP—Group of successive pictures within a coded video stream. MPEG, MPEG-2 and MPEG-4 compression products apply a GOP structure to their video compression systems. Each coded video stream consists of successive GOPs. From the pictures contained in it, the visible frames are generated. A GOP begins with an I-frame containing the full temporal resolution of the video frame. A series of predictive information is calculated between I –frames. P-frames are predictive and estimate forward, B-frames apply bi-directional prediction and estimate forwards and backwards. Products will apply GOP structures in different manners to support the needs of different applications be it: low delay, low bit rate or error resilience.

Leave a comment

Please note, comments must be approved before they are published