DEVELOPMENT AND A NEW EVALUATION TECHNIQUE OF PRECISE POINTING CONTROL-SYSTEM OF COMETS FEEDER-LINK ANTENNA

In order to achieve the precise pointing control of on-board antennas for geostationary spacecraft in the coming decade, an Antenna Pointing System (APS) has been developed for this purpose, and it has been eva luated by a newly proposed ground testing technique. This paper descri bes two features of the development of this system. One of these is a proposed control algorithm using a Pseudo Rate Modulator (PRM) and fli ght hardware characteristic to achieve 0.01 degree accuracy of beam po inting to compensate for the variance of 0.20 degrees in orbit. The ot her feature is a newly proposed technique for a dynamic closed-loop te st to simulate the auto-tracking of the quasi-fluctuation of the trans mitter target for equivalent conditions in orbit. The algorithm and te sting method have been applied to the COMETS (Communication and Broadc asting Engineering Test Satellite) feeder-link antenna APS, and they w ere evaluated by an engineering model.