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Gain

A measure of amplification measured in dB (decibels).

Generation

A copy or replication of an audio or video signal. Each generation or copy is further removed from the original signal. In the analog realm, each generation introduces degradation of the signal quality. In digital, each generation is exactly the same as its source.

Geostationary

Refers to a satellite in orbit in the equatorial plane with zero inclination, with an orbital velocity equal to the rotational speed of the earth and are located 22, 237 miles above the surface of the earth.  Satellites with these three characteristics appear to hover over one location on the earth's equator.

Geosynchronous

The Clarke Belt is a circular orbit situated over the earth's equator at a distance of 22, 237 miles.  Satellites placed in this orbit over the equator with an orbital speed that matches the earth's rotational speed are referred to as geosynchronous satellites.  See geostationary directly above.

Gigahertz (GHz)

One billion cycles per second.  Signals above 3 GHz are known as microwaves.   Above 30 GHz signals are known as millimeter waves.  At cycles above the millimeter wave range signals begin to take on the characteristics of lightwaves.

Global Beam

A down-link antenna pattern used by Intelsat satellites which effectively covers one-third of the earth's surface.  Global beams are aimed at the center of the Atlantic, Pacific and Indian Oceans by the respective Intelsat satellites thus enabling nations on opposite sides of these oceans to transmit and receive signals from at least one shared satellite.  Due to the broad beam coverage the global beam transponders exhibit a much lower EIRP than conventional transponders and larger satellite dishes (typically 10 meters (approx. 30 feet)) and above in order to receive these signals reliably.

GPS (Global Positioning Satellite)

A network of satellites which make it possible to use GPS based receivers to determine your exact physical location on the earth's surface with a high degree of accuracy.   For sophisticated public equipment the margin of error is below three feet.

G/T (Gain/Noise Temperature)

A figure of merit  of an antenna and a low-noise amplifier combination expressed in dB.  "G" is the net gain of the system and "T" is the noise temperature of the system.  The higher the value is the better the performance specifications of the system.

Guard Channel (Guard Band)

Satellite television channels (transponders) are separated by a narrow frequency band on both the upper and lower end.  This guard band is usually at least 2 MHz wide.  This separation helps eliminate the possibility of adjacent signals interfering with one another.

 

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