Pulse counter frequency modulation detection

Claim 1

APPARATUS FOR DEMODULATING A FREQUENCY MODULATED, GENERALLY SINUSOIDAL INPUT SIGNAL COMPRISING: FIRST ELECTRICALLY RESPONSIVE, BISTATE SWITCHING MEANS ADAPTED TO HAVE SAID INPUT SIGNAL APPLIED THERETO AND RESPONSIVE TO A PAIR OF TIME-SPACED AMPLITUDES OF SAID SIGNAL FOR PRODUCING A FIRST SERIES OF ELECTRICAL PULSES, EACH OF WHICH OCCURS DURING A CORRESPONDING CYCLE OF SAID SIGNAL AND WHICH COMMENCES SUBSTANTIALLY COINCIDENT IN TIME WITH ONE OF SAID AMPLITUDES AND TERMINATES SUBSTANTIALLY COINCIDENT IN TIME WITH THE OTHER AMPLITUDE; CIRCUIT MEANS COUPLED WITH SAID ELECTRICAL MEANS AND RESPONSIVE TO SAID FIRST SERIES OF PULSES FOR ELECTRICALLY DIFFERENTIATING THE LATTER, WHEREBY TO PROVIDE A SECOND SERIES OF ELECTRICAL PULSES; ELECTRICAL MEANS COUPLED WITH SAID CIRCUIT MEANS AND RESPONSIVE TO EVERY OTHER PULSE OF SAID SECOND SERIES OF PULSES FOR PROVIDING A THIRD SERIES OF PULSES OF EQUAL DURATION, EACH OF WHICH SUBSTANTIALLY COINCIDES IN TIME WITH A CORRESPONDING PULSE OF SAID SECOND SERIES OF PULSES; A SOURCE OF CONSTANT, DIRECT VOLTAGE; SECOND ELECTRICALLY RESPONSIVE SWITCHING MEANS PROVIDED WITH LOAD SWITCHING TERMINALS COUPLED WITH SAID SOURCE AND CONTROL TERMINALS COUPLED WITH SAID ELECTRICAL MEANS, SAID SECOND SWITCHING MEANS BEING RESPONSIVE TO SAID THIRD SERIES OF PULSES FOR PROVIDING A TRAIN OF OUTPUT PULSES AT SAID LOAD SWITCHING TERMINALS, WHEREBY EACH OF SAID OUTPUT PULSES IS OF THE SAME AMPLITUDE AND OF A WIDTH SUBSTANTIALLY EQUAL TO SAID DURATION; AND OUTPUT MEANS COUPLED WITH SAID LOAD SWITCHING TERMINALS AND RESPONSIVE TO SAID TRAIN OF OUTPUT PULSES FOR INTEGRATING SAID TRAIN, WHEREBY TO PROVIDE AN OUTPUT SIGNAL HAVING AN AMPLITUDE LEVEL PROPORTIONAL TO THE FREQUENCY OF SAID INPUT SIGNAL.