G

GEO - Geosynchronous Earth Orbit satellite. Geosynchronous systems include Inmarsat and OmniTRACS. The Inmarsat system uses allocations in the 6 GHz band from the ground station to the satellite, 1.5 GHz for the satellite-to-terminal downlink, 1.6 GHz for the terminal-to-satellite uplink, and 1 GHz from the satellite to the ground station.

Glare Hold and Glare Release - A method of glare resolution. Glare occurs when both the local and distant end of a trunk are seized at the same instant; this usually results in deadlock of the trunk. To prevent this, one end of the trunk is assigned a glare hold status and the other a glare release status. In the event of glare, the glare hold end holds the trunk and the glare release end releases the trunk and attempts to seize another. Used between MTSO and connecting cell sites.

GLONASS - The Russian Global Navigation Satellite System is similar in operation and may prove complimentary to the NAVSTAR system. Launched in 1996, is a 24 satellite constellation 19,100 Km above the earth in three orbital planes.

GMSK - Gaussian Minimum Shift Keying. A form of frequency shift keying which shapes pulses to minimize spectral leakage. Used in GSM.

GNSS - Global Navigation Satellite Systems. Extended GPS systems, providing users with sufficient accuracy and integrity information to be useable for critical navigation applications.

GPS - Global Positioning Satellite. Satellite-based radio positioning systems that provide 24 hour three-dimensional position, velocity and time information to suitably equipped users anywhere on or near the surface of the Earth (and sometimes off the earth). GPS is a 24 satellite constellation, 20,000 Km above the earth in six orbital planes. The NAVSTAR system, operated by the U.S. Department of Defense, was the first GPS system widely available to civilian users.

Grade-of-Service - A measure of what percentage of calls placed through an exchange fail to be completed due to congestion of that exchange. In cellular, a 2% GOS is considered acceptable.

GSM - Global System for Mobiles.