Search Keyword By: G

Description

GAA

Generic Authentication Architecture

gain

The ratio of output current, voltage, or power to input current, voltage, or power, respectively. Note 1: Gain is usually expressed in dB. Note 2: If the ratio is less than unity, the gain, expressed in dB, will be negative, in which case there is a loss between input and output.

gain hit

See hit.

gain medium

An active medium, device, or system in which amplification of input occurs with or without feedback. Note: Gain media include amplifiers, lasers, and avalanche photodiodes (APDs).

gain of an antenna

Synonym antenna gain.

gamma correction

In video, the insertion of a nonlinear output-input characteristic for the purpose of changing the system transfer characteristic. [IEEE 100] Note: Historically, gamma correction was a precompensation applied to the video signal at the camera to correct for the nonlinearities of the CRT (i.e., the power function of the electron gun) and, as such, it was the inverse of the electron gun function. It is now widely used, however, to describe “the total of all transfer function manipulations” (i.e., including departures from a true power-law function), whether inherent or intentionally introduced to act upon the video signal for the purpose of reducing the bandwidth for signal processing, making the image on the final display conform to preconceived artistic objectives, or providing noise suppression, or even bit-rate reduction.

gap

A period of low energy content signals present of a digital speech interpolation device. [T1.509-1995]

gap loss

The power loss that occurs when an optical signal is transferred from one fiber to another that is axially aligned with it, but longitudinally separated from it. Note: The gap allows light from the “transmitting” fiber to spread out as it leaves the fiber endface. When it strikes the “receiving” fiber, some of the light will enter the cladding, where it is quickly lost. [After FAA] 2. An analogous form of coupling loss that occurs between an optical source, e.g., an LED, and an optical fiber. Note: Gap loss is not usually significant at the optical detector, because the sensitive area of the detector is normally somewhat larger than the cross section of the fiber core. Unless the separation is substantial, all light emerging from the fiber, even though it diverges, will still strike the detector. Synonym longitudinal offset loss. [FAA]

gap loss image

gap-loss attenuator

An optical attenuator that exploits the principle of gap loss to reduce the optical power level when inserted in-line in the fiber path; e.g., to prevent saturation of the receiver. Note: Gap-loss attenuators should be used in-line near the optical transmitter. [After FAA]

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