Data transmission by variable phase with two transmitted phase reference signals

Claim 1

IN A SYSTEM FOR TRANSMITTING PHASE MODULATED MULTIPLEXED SIGNALS ON A TRANSMISSION CHANNEL CONTAINING A VARIABLE PHASE SHIFT INTRODUCING PORTION, MEANS FOR PRODUCING A FIRST REFERENCE FREQUENCY SIGNAL, MEANS FOR PRODUCING A PLURALITY OF PHASE MODULATED INFORMATION SIGNALS WHICH ARE PHASE RELATED TO SAID REFERENCE SIGNAL AT A FREQUENCY DIFFERENT THEREFROM, MEANS FOR PRODUCING A SECOND REFERENCE SIGNAL WHICH IS PHASE RELATED TO SAID FIRST REFERENCE FREQUENCY SINGAL AT A SELECTED FREQUENCY DIFFERENCE THEREFROM, MEANS FOR APPLYING SAID SIGNALS TO SAID CHANNEL, MEANS FOR RECEIVING SAID SIGNALS FROM SAID CHANNEL, AND MEANS FOR COMPARING THE DIFFERENCE FREQUENCY BETWEEN ONE REFERENCE AND EACH INFORMATION SIGNAL WITH A HARMONIC INCLUDING UNITY OF THE DIFFERENCE FREQUENCY BETWEEN THE TWO REFERENCE SIGNALS TO DERIVE AN OUTPUT SIGNAL IN DEPENDENCY ON THE MODULATION OF EACH INFORMATION SIGNAL.