Glossary Terms Beginning G

0-9 : A : B : C : D : E : F : G : H : I : J : K : L : M

N : O : P : Q : R : S : T : U : V : W : X : Y : Z

G.711: ITU-T specification for audio data coding using 64 kbps of bandwidth to provide 3 kHz telephone quality audio.
G.722: ITU-T specification for audio data coding using 64 kbps of bandwidth to provide 7.5 kHz audio over a 64 kbps circuit.
G.728: ITU-T specification for audio data coding using 16 kbps of bandwidth to provide 3 kHz audio of bandwidth.
G/T: See figure of merit.
Gain: Measure of amplification expressed in dB.
Gain step: The gain setting of a transponder, which can be varied in discrete steps from the TT&C ground station according to operational requirements.
GAN: Global Area Network: see M4.
GEO: Geostationary Earth Orbit.
Geostationary: Earth orbit GEO: describes a special geosynchronous orbit which is symmetrical above the Equator such that the satellite appears to remain stationary relative to a location on the surface of the Earth.
Geosynchronous orbit: Describes a circular orbit around the Earth, with an average distance from the centre of the Earth of about 42 000 km (26 000 miles) in which the satellite orbit has a period equal to the rotation period of the Earth.
GHz: Gigahertz: unit of frequency equal to one thousand million cycles per second, or 1 × 109 Hz (1 000 000 000 Hz).
Glitch: Imperfections in a digital signal.
GMDSS: Global Maritime Distress and Safety System: operated by INMARSAT as a life-saving service.
GMPCS: Global Mobile Personal Communication by Satellite.
GPRS: General packet radio services: wireless packet-data service; part of the thirdgeneration of digital cellular telephony (3G).
GPS: Global Positioning System: satellite-based navigation system.
Graveyard orbit: Orbital positions at 105°W and 75°E where satellites are moved or allowed to drift to at the end of their operational lives; thus this space junk can then be monitored to reduce the risk of debris damaging any active spacecraft.
Ground station: Generic term for satellite communications earth station.
GSM: Global System for Mobile Communications: digital cellular telephony standard.
Guard-band; guard-channel: Separation of signals in a transponder to minimize the risk of interference with each other.