Dual modulation communication system

Claim 1

A DEMODULATOR CIRCUIT FOR A SIMULTANEOUS FREQUENCY MODULATED AND AMPLITUDE MODULATED CARRIER SIGNAL WITH INDEPENDENT BANDS ABOUT A CENTRAL CARRIER FREQUENCY COMPRISING AN INPUT AMPLIFIER STAGE HAVING AN OUTPUT TUNED TO THE CARRIER FREQUENCY, A DISCRIMINATOR CONTAINING A CIRCUIT RESONANT AT THE CARRIER FREQUENCY COUPLED TO THE OUTPUT OF SAID AMPLIFIER STAGE AND A PAIR OF DIODES CIRCUIT CONNECTED WITHIN THE DISCRIMINATOR FOR DEMODULATING THE FREQUENCY MODULATED BAND OF THE CARRIER SIGNAL, CIRCUIT MEANS CONNECTED ACROSS SAID DIODES TO ESTABLISH AN AUDIO RESPONSE AT A FIRST TERMINAL THEREOF CORRESPONDING TO THE FREQUENCY MODULATED BAND, SAID PAIR OF DIODES FURTHER SERVING AS DETECTOR MEANS FOR DETECTING THE AMPLITUDE MODULATED SIGNAL IN SAID CARRIER SIGNAL SIMULTANEOUSLY WITH DETECTOR OF SAID FREAQUENCY MODULATED SIGNAL TO PROVIDE SAID DETECTED AMPLITUDE MODULATED SIGNAL AT A SECOND TERMINAL OF SAID DISCRIMINATOR, MEANS INCLUDING CARRIER FREQUENCY FILTER MEANS CIRCUIT CONNECTED BETWEEN SAID CIRCUIT MEANS AND TO THE INPUT OF SAID AMPLIFIER STAGE FOR APPLYING THE AUDIO SIGNALS THERETO, AN IMPEDANCE IN THE AMPLIFIER CIRCUIT FOR ESTABLISHING A LOW IMPEDANCE OUTPUT SIGNAL CORRESPONDING TO SAID AUDIO RESPONSE, AND SECOND CIRCUIT MEANS FOR COUPLING SAID DETECTED AMPLITUDE MODULATED SIGNAL TO CORRESPONDING OUTPUT MEANS, SAID AMPLIFIER STAGE PROVIDING BOTH AMPLIFICATION OF SAID SIMULTANEOUSLY MODULATED AMPLITUDE MODULATED AND FREQUENCY MODULATED SIGNAL TO SAID DISCRIMINATOR AND SAID LOW IMPEDANCE OUTPUT AMPLIFICATION OF SAID DETECTED AUDIO SIGNAL.