The initial acquisition unit of the French/German TDMA-system for Intelsat application

The purpose of the initial acquisition procedure is to ensure that the burst sequence transmitted by a ground station after a long interruption period does not interfere with the signals of other stations of the TDMA system. This means that the transmission phase of the burst sequence must be evaluated in such a way that this burst sequence is received by the satellite in the predetermined time slots of the existing TDMA frame. This paper discusses some basic problems of the standardized initial acquisition procedure as implemented for the French/German TDMA terminal for Intelsat application. The following three aspects of the procedure are emphasized: (1) the carrier synchronization technique with particular attention to level variations occurring on the satellite path; (2) PN (pseudo-noise) synchronization with emphasis on specified acquisition accuracy; and (3) the problem of maintaining carrier synchronism during the PN synchronization procedure.