A satellite communications system comprises a transmitting ground station, including a transmitter and a receiver, a satellite transponder and a receiving ground station. The transmitter transmits an uplink signal to the satellite transponder, which broadcasts the received uplink signal as a downlink signal to the receiving ground station. The transmitting ground station monitors the downlink signal through the receiver and calculates log-likelihood ratios (LLRs) as a function of the monitored downlink signal. These LLRs are illustratively stored in a look-up table, which are then transmitted to the receiving ground station for use in recovering data from a received data signal.