Synchronization burst transmit phase control system

Claim 1

In an SS/TDMA (Satellite-Switched Time Division Multiple Access) communications system having at least one up-link and one down-link which include a plurality of spot beams, the up- and down-links being sequentially switched according to a predetermined connection mode by a satellite born switch, and the switching of the connection being repeated at a predetermined frame period according to a timing reference provided in a satellite; a sync burst transmit phase control system in which a predetermined satellite communications reference station for establishing and maintaining a TDM frame between earth stations, which correspond to a plurality of different beam spot zones, comprises: means for switching a metric pattern included in a predetermined sync burst which is transmitted to the satellite, said burst being based on a period corresponding to the TDMA frame and, then, said burst is returned from said satellite after being gated off by a sync window which is generated on a basis of a reference time in said satellite and adapted for regulation of the TDMA frame; means responsive to a synchronization control operation performed by using a first metric pattern for determining a synchronization accuracy which is obtainable with the first metric pattern by averaging transmit phase correction values, which are necessary for maintaining synchronization, over a predetermined period of time; means responsive to a synchronization control operation performed by using a second metric pattern for determining a synchronization accuracy which is obtainable with the second metric pattern by averaging transmit phase corrections, which are necessary for maintaining synchronization, over a predetermined period of time; and means for comparing the synchronization accuracy with a predetermined synchronization accuracy at a predetermined period; whereby any of the metric patterns is selected which provides a highest synchronization accuracy at a particular moment.

Claim 7

A system for enabling a plurality of stations to communicate with each other by synchronized bursts transmitted via satellite, a metric pattern included in each burst, one of said stations being designated a reference station, means for generating two separate metric patterns either one of which may be transmitted with said burst signal for synchronizing said burst signal, means for measuring the synchronization accuracy of a burst including a transmitted one of said metric patterns, and means responsive to said measuring means finding an unacceptable accuracy for switching to the other of said metric patterns.

Claim 8

A system for enabling a plurality of stations to communicate with each other by synchronized bursts transmitted via satellite, a metric pattern included in each burst, one of said stations being designated a reference station, means for generating two separate metric patterns either one of which may be transmitted with said burst signal for synchronizing said burst signal, means for measuring the synchronization accuracy of a burst including a transmitted one of said metric patterns, and means responsive to said measuring means finding an unacceptable accuracy for switching to the other of said metric patterns.