Compensation of frequency offset

摘要

In a satellite mobile communication system in which at least one mobile earth station communicates with a land earth station which is coupled with a network, through a satellite, the land earth station measures frequency offset in a request signal and/or a response signal in a received signal from the mobile earth station due to frequency offset by a transponder in the satellite and/or a local oscillator of said mobile earth station, and doppler shift due to movement of the satellite. The measured frequency offset is forwarded to the mobile earth station through a singalling channel or a communication channel through a satellite. The mobile earth station compensates frequency offset by adjusting oscillation frequency of a local oscillator in the mobile station based upon the measured frequency offset sent from the land earth station.