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Glossary of Terms

Glossary of Terms

Gain
A general term used to denote an increase in signal power or voltage produced by an amplifier in transmitting a signal from one point to another. The amount of gain is usually expressed decibels above a reference level. Opposite of Attenuation.
Gamma
The light output of a CRT is not linear with respect to the voltage input. This non-linearity follows an exponential function called "Gamma".
Gateway
The original Internet term for what is now called router or more precisely, IP router. Refers to systems that translate from one native format to another.
GenLock
A method of synchronizing video equipment by using a common, external "Genlock" signal. A device which locks the frequency of it's internal sync generator to an external source.
Ghost
A shadowy or weak image in the received picture, offset either to the right or to the left of the primary image. It is the result of transmission conditions where secondary signals are created and received earlier or later than the primary signal caused by a reflected RF signal.
Giga
Acronym for billions. (G) e.g. One Gigabyte = 1 billion bytes.
Gigahertz (GHz)
One billion cycles per second. Signals operating above 3 Gigahertz are known as microwaves. Above 30 GHz they are know as millimeter waves. As one moves above the millimeter waves signals begin to take on the characteristics of light waves. (GHz) 1,000,000,000 Hertz; a unit of frequency.
GLI
Ground Loop Isolator - Devices, such as Extron's GLI 250, that isolate the video signals from any system ground problems.
Gradation
The slow change of a color's density, a change in tone, texture, etc., between adjacent areas of an object or the corresponding image.
Graphical User Interface (GUI)
A visual metaphor that uses icons that represent actual items that can be selected or manipulated with a pointing device.
Graphics Monitor
A monitor with horizontal scan capable of 15.75 - 75 (80) kHz. Graphics monitors and projectors accept inputs from NTSC Video, CGA, and VGA, as well as, high resolution workstations.
Gray Scale
Refers to the range of light transmission in a number of steps, e.g., a 17 step gray scale for a monochrome product would have white (or very light gray), 15 shades of gray from light to dark, and black (or very dark gray) while in a color application, each primary complement (cyan, magenta, yellow) would vary from white, light through dark versions of the color, to fully saturated color. The three combined could make as many as 4,913 (17 x 17 x 17) colors.
Ground
A conducting connection by which an electric circuit or equipment is connected to the earth to establish and maintain a reference voltage level. Also known as the voltage reference point in a circuit.
Ground Loop
A potential system grounding problem that may produce symptoms that appear as sync noise and causes a horizontal bar to "roll" vertically on the video image. A ground loop occurs when some devices in a system are not connected to the same electrical ground. This can create a voltage potential between "ground" on the different pieces of equipment. See GLI.
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