Multilevel vestigial sideband suppressed carrier data transmission system

Claim 1

A PARTIALLY SUPPRESSED CARRIER DATA TRANSMISSION SYSTEM COMPRISING IN COMBINATION: A TRANSMITTER FOR TRANSMITTING CODED INFORMATION SIGNALS AND A RECEIVER ELECTRICALLY CONNECTED TO SAID TRANSMITTER BY A SUITABLE TRANSMISSION MEDIUM, SAID TRANSMITTER INCLUDING A SOURCE OF DATA SIGNALS, A SOURCE OF CLOCK SIGNAL, A SOURCE OF CARRIER SIGNAL, MEANS FOR MODULATING SAID CARRIER SIGNAL WITH SAID DATA SIGNAL FOR PRODUCING TRANSMITTED SIGNALS, MENS COUPLED TO SAID SOURCE OF DATA SIGNALS AND SAID SOURCE OF CARRIER SIGNAL FOR ADDING TO SAID TRANSMITTED SIGNALS, A PERIODIC SIGNAL CONSISTING OF SAID CARRIER SIGNAL HAVING A FIXED DATA SIGNAL LEVEL ADDED THERETO, MEANS COUPLED TO SAID SOURCE OF CARRIER SIGNAL AND SAID SOURCE OF CLOCK SIGNAL FOR MULTIPLYING THE CARRIRE SIGNAL OF CLOCK SIGNAL FOR MULITPLYING THE FOR ADDING TO SAID TRANSMITTED SIGNAL, A CONTINUOUS SIGNAL CONSISTING OF A COMPONENT OF THE PRODUCT OF SAID CLOCK SIGNAL AND SAID CARRIER SIGNAL HAVING A FREQUENCY GREATER THAN THE SPECTRUM OF SAID TRANSMITTED SIGNALS, SAID RECEIVER INCLUDING A CARRIER RETRIEVAL CIRCUIT RESPONSIVE TO SAID TRANSMITTED SIGNALS FOR DETECTING SAID CARRIER SIGNAL, A DEMODULATOR CONNECTED TO SAID CARRIER RETRIEVAL CIRCUIT AND RESPONSIVE TO SAID TRANSMITTED SIGNALS FOR DEMODULATING SAID TRANSMITTED SIGNALS, A DETECTOR COUPLED TO THE OUTPUT OF SAID DEMODULATOR, AN D A DECORDER COUPLED TO THE OUTPUT OF SAID DETECTOR FOR PRODUCING OUTPUT DATA SIGNALS, PHASE CORRECTING MEANS COUPLED TO SAID CARRIER RETRIEVAL CIRCUIT AND SAID DEMODULATOR AND RESPONSIVE TO SAID PERIODIC SIGNAL ADDED TO SAID TRANSMITTED SIGNAL FOR PROVIDING A PHASE CORRECTING PULSE TO SAID CARRIER RETRIVAL CIRCUIT FOR ESTABLISHING THE PROPER INITIAL PHASE FOR THE OUTPUT SIGNAL FROM SAID CARRIER RETRIEVAL CIRCUIT, A CLOCK RETRIEVAL CIRCUIT COUPLED TO SAID DECODER AND RESPONSIVE TO SAID CONTINUOUS SIGNAL ADDED TO SAID TRANSMITTED SIGNAL FOR PROVIDING A CLOCK SIGNAL TO SAID DECODER FOR PRODUCING DECODED OUTPUT DATA SIGNALS, AND AN AUTOMATIC THRESHOLD CONTROL CIRCUIT COUPLED TO SAID DETECTOR AND SELECTIVE RESPONSIVE TO SAID PERIODIC AND CONTINUOUS SIGNALS FOR PROVIDING A SIGNAL TO SAID DETECTOR FOR VARYING THE THRESHOLD LEVELS THEREOF IN ACCORDANCE WITH VARIATIONS OF SAID PERIODIC AND CONTINUOUS SIGNALS DUE TO TRANSMISSION.