Operational experience with CENSAR

The CENSAR concept for synchronization in TDMA systems is described. Synchronization is necessary to ensure no overlap of signal bursts received at the satellite and minimization of the interburst guard time. The problem of synchronizing many stations is compounded by the drift motion of the satellite. In the CENSAR system it was decided to exploit the economy and accuracy of centralized synchronization. The system uses those stations, each of which send a short burst to the satellite measure round trip delay, and transmit a time mark signal derived from control station information. The satellite is at the intersection of three ellipsoids of rotation.