Doppler frequency shift correction of information band frequencies in a transmitted carrier system using a single pilot signal

Claim 1

IN A COMMUNICATION SYSTEM HAVING A VARIABLE PATH LENGTH BETWEEN A TRANSMITTING TERMINAL AND A RECEIVING TERMINAL, A CARRIER SIGNAL COUPLING SAID TERMINALS, SAID CARRIER SIGNAL BEING MODULATED BY A PLURALITY OF INFORMATION-CARRYING SIGNALS OCCUPYING DISCRETE FREQUENCY BANDS AND A PILOT SIGNAL FREQUENCY REMOTE FROM SAID INFORMATION BANDS OF FREQUENCIES, SAID PILOT SIGNAL AND EACH INFORMATION-CARRYING SIGNAL BEING SHIFTED IN FREQUENCY BY AN AMOUNT DETERMINED BY THE RATE OF CHANGE OF SAID PATH LENGTH BETWEEN SAID TERMINALS AND THE FREQUENCY OF SAID CARRIER SIGNAL AND THE FREQUENCIES OF SAID INFORMATIONCARRYING SIGNALS, SAID RECEIVING TERMINAL COMPRISING, A FILTER MEANS FOR SEPARATING EACH FREQUENCY BAND AND SAID PILOT SIGNAL AND COUPLING THEM TO INDIVIDUAL CHANNELS, A PLURALITY OF MULTIPIER CIRCUITS CONNECTED IN THE PILOT SIGNAL CHANNEL FOR CHANGING THE SHIFTED FREQUENCY OF SAID PILOT SIGNAL TO PRESELECTED FREQUENCIES, AND MEANS IN EACH INFORMATION-CARRYING SIGNAL CHANNEL FOR COMBINING THE INFORMATION-CARRYING SIGNAL OF THAT CHANNEL WITH A PRESELECTED FREQUENCY FROM THE OUTPUT OF A MULTIPLIER CIRCUIT HAVING A MULTIPLE OF THE FREQUENCY SHIFT OF THE PILOT SIGNAL THAT IS APPROXIMATELY EQUAL TO THE AVERAGE FREQUENCY SHIFT OF THE INFORMATION-CARRYING SIGNALS IN THE FREQUENCY BAND OF THAT PARTICULAR CHANNEL.