System for data communication by phase shift of square wave carrier

Claim 1

A DIGITAL COMMUNICATIONS SYSTEM COMPRISING IN COMBINATION: A SOURCE OF REGULARLY OCCURING SQUARE WAVE CARRIER SIGNALS, A SOURCE OF BINARY CODED DATA, SAID DATA BEING REPRESENTED BY A SERIAL TRAIN OF BIVALUED PULSES, MODULATOR MEANS CONNECTED TO RECEIVE SAID CARRIER SIGNALS AND SAID SERIAL SIGNAL TRAIN FOR PRODUCING MODULATED CARRIER SIGNALS WHEREIN PHASE SHIFTS OF SAID CARRIER SIGNALS ARE GENERATED ON CHANGES OF STATE OF SAID PULSES IN SAID SIGNAL TRAIN, MEANS FOR TRANSMITTING SAID MODULATED CARRIER SIGNAL TRAIN TO A RECEIVING STATION, SAID RECEIVING STATION INCLUDING A SOURCE OF CLOCK SIGNALS, SYNCHRONIZING MEANS RESPONSIVE TO THE RECEIVED MODULATED CARRIER SIGNALS FOR PRODUCING AN OUTPUT PULSE EACH TIME THE LEVEL OF SAID RECEIVED MODULATED CARRIER SIGNALS CHANGES FROM ONE BINARY VALUE TO THE OPPOSITE BINARY VALUE, MEANS CONNECTING SAID SYNCHRONIZING MEANS TO SAID SOURCE OF CLOCK SIGNALS SUCH THAT SAID OUTPUT PULSES CONTROL SAID SOURCE OF CLOCK SIGNALS, AND MEANS CONNECTED TO RECEIVE SAID RECEIVED MODULATED CARRIER SIGNALS AND SAID CLOCK SIGNALS FOR SEPARATING SAID CARRIER SIGNALS FROM SAID RECEIVED MODULATED CARRIER SIGNALS.