ANALYSIS OF A SATELLITE ANTENNA TRACKING LOOP DRIVEN BY BPSK MODULATED SIGNALS

The subject of this paper is an antenna tracking system used to mainta in an antenna on board a geosynchronous (GEO) satellite, pointed towar ds a low earth orbit (LEG) satellite. The tracking system uses the BPS K modulated signals transmitted from the LEO satellite. The signal is received by an electronically switched antenna beam. A suitable proces sing of the received signal level then generates an error voltage whic h drives a tracking loop. The measurement of the received signal level is implemented by a power detector. Analysis of the antenna tracking algorithm is carried out and the performance is given in terms of line arized mean-square tracking error. The mean-square tracking error is r elated to the antenna beam parameters, to the closed loop bandwidth an d to the statistics of the power measurement process. In particular, i t is shown that a key parameter for the tracking loop proportional to the variance of the pointing error, and a theory has been developed to find an accurate expression for the SNR. (C) 1997 John Wiley & Sons, Ltd.