Patent ID: 8233562

Claim:
An automatic equalizing circuit and system for a closed-loop satellite communication system comprising: a transmitter system configured to receive a digital data input signal and send a transmit signal to a satellite in space; a satellite repeater at the satellite configured to receive the transmit signal, process the transmit signal and send the processed signal toward Earth; a receiver system on Earth configured to receive the processed signal from the satellite repeater; and an automatic equalizer on Earth between the receiver system and the transmitter system, the automatic equalizer comprising at least a backward complex infinite impulse response (IIR) filter and a forward finite impulse response (FIR) filter in series with a Nyquist filter, the automatic equalizer configured to: measure an impulse response of a communication channel from the signal received by the receiver system, the communication channel comprising at least the transmitter system and the satellite repeater; calculate an inverse filter response for the communication channel based on the impulse response; and digitally modulate the digital data input signal with the inverse filter response in the digital domain to pre-distort the digital data input signal before it is sent by the transmitter system.