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Dictionary of Technical Terms - G
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G
Gain
Any increase or decrease in strength of an
electrical signal. Gain is measured in terms of decibels or
number-of-times of magnification.
gain/frequency distortion
A circuit defect in which a change in frequency
causes a change in signal amplitude. When this happens to a
television signal, it can cause serious distortions in color
saturation, as well as a lack of vertical line resolution due to
luminance pulse ringing.
gamut
The range of valid voltages allowed for a video
signal, or a component of a video signal. Signal voltages outside
of the range (i.e., exceeding the gamut) may lead to clipping,
crosstalk, or other distortions.
gate
1. A signal used to trigger the passage of other
signals through a circuit. 2. A digital logic device whose output
state depends on the states of the logic signals presented to its
inputs.
gate array
A set of basic logic gates contained in one
integrated circuit.
GBR (green, blue, & red; RGB)
The three primary colors used in video processing,
often referring to the three unencoded color camera outputs. The
GBR letter sequence indicates the mechanical sequence of connectors
in the SMPTE standard.
general purpose interface (GPI)
1. A parallel interconnection scheme that allows
remote control of certain functions of a device. One wire per
function. 2. May also refer to any non-specific interface between
equipment. Usually refers to a serial connection (RS232 or RS422
format) between computer modules.
generation
A copy. A first generation copy is a copy of the
master tape. A second generation copy is a copy of the first
generation copy.
generation loss
Losses caused by copying from one videotape to
another.
gen-lock (genlock)
To phase-lock the timing of one piece of equipment
to another.
gen-lockable master
A main facility sync pulse generator that is capable
of locking to an outside source of video.
gen-lock module
A module that can phase-lock to another source of
video or sync.
ghost
In a television picture, a duplicate image offset
from the main picture image.
GHz
Gigahertz. One thousand megahertz.
glitch
A general term used for a wide variety of momentary
signal discontinuities, such as tears, rolls, momentary loss of
picture, etc.
global channel, global control
In digital picture manipulators, allows an object
constructed of separate layers, each from individual channels, to
be manipulated as one layer.
GPI
General purpose interface.
graded index fiber
An optical fiber in which the core has a continually
changing refractive index.
granularity
The smallest unit size available for a particular
routing system. For example the granularity of a router may be 16 x
16, meaning that additional routing capacity must be added in
minimum units of 16 x 16.
graphics display
A standard video output of the Kadenza or
Kaleidoscope system showing wire frames of Kaleidoscope
transformations. This is used to aid operators in quickly building
multi-layered effects.
Graphics Factory Halo
A Grass Valley video graphics system featuring
dimensional video typography, designer painting, and 3D modeling
and animation.
gray scale
Range of luminance levels from black to white.
green
One of the three primary color signals (red, green
and blue) produced by cameras and other video sources.
greenie
Nickname for a brand of small screwdriver having a
green handle, sometimes used for calibrating video equipment.
ground loop
A condition when two or more paths to ground exist
and a voltage is induced unequally in these paths, causing
interference, such as hum, buzz, or noise.
group delay
A signal defect caused by different frequencies
having differing propagation delays (delay at 1 MHz is different
from delay at 5 MHz). In the television picture, delay between the
chrominance and luminance components of the video signal causes an
object's color to shift outside the object's outline and also
causes ringing in the luminance component.
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