Automatic frequency and gain control circuit.

摘要

An AFC/AGC circuit utilized in a receiving apparatus of a ground station for the satellite communication system comprising a digital AFC/AGC controller functioning such that;

when the pilot signal is not received, the gain control voltage and the frequency control voltage are respectively set to appropriate values based on the predetermined data;

when the pilot signal starts to be received, the gain and frequency control voltages are switched from the set values to the values obtained from the digital AFC and AGC processings, respectively;

so long as the pilot signal is being received, the signal generated in the digital AFC and AGC processings are sampled by respective sampling clock signals and the gain and frequency control voltages are determined in accordance with the sampled data; and

when the pilot signal stops to be received, each of the gain and frequency control voltages is held at the value sampled by a last pulse of the sampling clock signal immediately before the stopping, respectively.