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Globalstar is a satellite communications system that uses 48 LEO satellites orbiting the Earth on eight orbits at an altitude of 1,414 km. Each orbit has six satellites, each with a transmission capacity of 2,700 channels. Globalstar, which began service in 1999, covers about 100 countries worldwide with its footprints. In addition to mobile voice communications, Globalstar provides 9.6 kbit/s data transmission and navigation services.

Globalstar satellites transmit on the following frequency ranges. The lower frequency range is 1.610 GHz to 1.6265 GHz for the uplink from the mobile station to the satellite and between 2.4835 GHz and 2.50 GHz for the downlink between the satellite and the mobile station. The other frequency ranges are 6.9 GHz for the downlink and 5.1 GHz for the uplink. The transmit power is relatively high at 1.2 kW. Modulation is in quadrature phase shift ke ying( QPSK); channel assignment is by means of code division multiple access( CDMA). The satellites do not use Inter Satellite Links( ISL), but establish a direct link to the nearest ground station. The ground station gateway establishes the connection to the terrestrial networks.

Globalstar cell phones, photo: Globalstar

Globalstar cell phones, photo: Globalstar

Globalstar is used for global communications services such as Global Mobile Personal Communications by Satellite( GMPCS), or Global Mobile Satellite System( GMSS).

Englisch: Globalstar
Updated at: 20.09.2011
#Words: 198
Links: satellite communications (Satcom), system, low earth orbiter (satellite comm.) (LEO), energy aware radio and network technologies (Earth), orbit
Translations: DE

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