US 3,995,111 AGranted

Transmit phase control system of synchronization burst for SDMA/TDMA satellite communication system

AssigneeFujitsu Limited

InventorsYoshikazu Tsuji, Yoshiro Tada

Life of this patent

Estimating the term…

Loading patent…

Abstract

A transmit phase control system of synchronization burst is disclosed for use in a SDMA/TDMA satellite communication system in which a phase error between a synchronization burst transmitted from an earth station and a synchronization window, assigned as a time slot on a satellite for returning the synchronization burst, is measured and the transmit phase of the synchronization burst is controlled based on the measured value. Phase error measurement is achieved a plurality of times in connection with the received synchronization burst of each station, and a decided phase error is derived based on the measured value obtained by the plurality of measurements. The transmit phase of the synchronization burst is then controlled in accordance with the decided phase error. Further, the phase error decision is achieved at every 1/n (n being an integer larger than 1) round trip and the present synchronization burst is transmitted with its transmit phase corrected corresponding to a value that is the sum of the phase corrected value of the n preceding phase correction instants subtracted from the decided phase error at the present instant.

Claims6

Dependent claims

A synchronization burst transmit phase control system for an SDMA/TDMA satellite communication system including earth stations and a satellite, said satellite produceing a synchronization window through which a synchronization burst transmitted from each earth station is returned by said satellite, and a plurality of data windows for communication between predetermined groups of earth stations and between the earth stations of each group, based on a timing signal of said satellite, wherein a round trip period is defined as the time commenced by a synchronization burst transmitted from an earth station and terminated when said same synchronization burst returns to said same earth station;

each of said earth stations comprising:
transmitting means for phase correcting each successive synchronization burst at a corresponding phase correction instant, and transmitting said phase corrected synchronization bursts to said satellite;
receiving means for receiving each synchronization burst transmitted by said transmitting means and returned from said satellite;
measuring means for measuring an error between the phase of the received synchronization burst of said earth station and that of the synchronization window, a plurality of times l during a corresponding phase control interval, and producing a measured value for each error measurement, wherein said phase control interval is defined as the time between successive phase correction instants;
deciding means for determining a decided phase error as a function of said l phase error measurements and producing a phase corrected value;
and
control means for receiving said phase corrected value and controlling the transmit phase of the synchronization burst with a phase control signal at a corresponding phase correction instant.

4 more elements

Dependencies are inferred from the claim text.