Performance Analysis of Noncoherent AGC for Signal Presence Detection and Autotrack Signal Extraction

Abstract

The acquisition of a communication satellite data signal starts with a spatial search for the incoming direction of arrival. As the antenna scans the received signal level builds up as this direction is approached. This level builds up according to the antenna gain pattern. Once detected, this level can be used to determine when the pull-in range is reached. This allows the automatic tracking, or the autotrack system to take over and maintain the pointing control. An AGC control voltage can provide an indication of signal level, gain, and thus the pointing error. A non-coherent AGC can be used to provide both a signal presence indication and tracking error signal, if a single channel autotrack signal with AM or AM-PM modulation is used. This includes five horn and dual mode feed systems.