Receiver for data with one frequency indicating one binary logic state and another frequency indicating other state

Claim 1

DECODING MEANS FOR DECODING A RECEIVED BIT SYNCHRONOUS SIGNAL IN WHICH EACH DATA BIT CONTAINS EITHER A HAVING A FREQUENCY F1 OR A WHOLE CYCLE OF SINE WAVE SHAPED SIGNAL HAVING A FREQUENCY 2F1 OF THE SAME PEAK AMPLITUDE AS SAID FIRST SIGNAL AND IN WHICH EACH BIT BEGINS AND ENDS AT A PEAK AMPLITUDE OF THE DATA REPRESENTING SIGNAL CONTAINED THEREIN, SAID DECODING MEANS COMPRISING DISCRIMINATOR MEANS FOR PRODUCING AN OUTPUT SIGNAL WHOSE POLARITY VARIES IN ACCORDANCE WITH CHANGE IN FREQUENCY OF THE RECEIVED ENCODED SIGNAL, DEMODULATOR MEANS INCLUDING A FULL-WAVE RECTIFIER RESPONSIVE TO THE RECEIVED BIT SYNCHRONOUS SIGNAL TO PRODUCE A DEMODULATED AND FULL WAVE RECTIFIED OUTPUT SIGNAL, OSCILLATOR MEANS RESPONSIVE TO THE OUTPUT SIGNAL OF SAID DEMODULATOR MEANS TO PRODUCE AN OUTPUT SIGNAL HAVING A FREQUENCY 2F1 AND HAVING A PHASE WHICH REMAINS CONSTANT WITH RESPECT TO THE PHASE OF THE BIT PERIOD OF THE RECEIVED BIT SYNCHRONOUS SIGNAL, FIRST PULSE-FORMING MEANS CONSTRUCTED TO DERIVE A FIRST PULSATING SIGNAL FROM THE OUTPUT SIGNAL OF SAID OSCILLATOR MEANS HAVING A REPETITION RATE 2F1 AND OCCURRING SUBSTANTIALLY WITH THE OCCURRENCE OF THE PEAK AMPLITUDES OF THE OUTPUT SIGNAL OF SAID DISCRIMINATOR MEANS, SECOND PULSEFORMING MEANS RESPONSIVE TO SAID DISCRIMINATOR MEANS OUTPUT SIGNAL AND SAID PULSATING SIGNAL TO PRODUCE A TWOLEVEL BIT SYNCHRONOUS SIGNAL CONTAINING THE INFORMATION CONTAINED IN THE RECEIVED ENCODED SIGNAL.