Multivibrator detector for stereophonic frequency modulation receivers

Claim 1

A RECEIVER FOR USING A STEREOPHONIC PROGRAM COMPRISING A CARRIER FREQUENCY-MODULATED IN ACCORDANCE WITH THE SUM OF TWO AUDIO SIGNALS, A SUBCARRIER SIGNAL WHICH HAS BEEN SUPPRESSED-CARRIER AMPLITUDE-MODULATED WITH THE DIFFERENCE OF SAID TWO AUDIO SIGNALS, AND A PILOT SIGNAL SUBHARMONICALLY RELATED TO SAID SUBCARRIER SIGNAL, SAID RECEIVER COMPRISING: A FREQUENCY-MODULATION DETECTOR RESPONSIVE TO SAID CARRIER FOR DERIVING A COMPOSITE SIGNAL REPRESENTING THE MODULATION OF SAID CARRIER; A MULTIVIBRATOR INCLUDING A PAIR OF CROSS-COUPLED ACTIVE DEVICES INDIVIDUALLY HAVING AN ELECTRODE SYSTEM INCLUDING AN ELECTRODE FOR CONTROLLING CONDUCTION IN THE DEVICE AND FURHTER HAVING A LOAD CIRCUIT; MEANS RESPONSIVE TO SAID PILOT TONE FOR DEVELOPING A DEMODULATION SIGNAL; MEANS FOR CONCURRENTLY APPLYING AT LEAST THE MODULATED SUPPRESSED-CARRIER COMPONENT OF SAID COMPOSITE SIGNAL TO SAID DEVICES OF SAID MULTIVIBRATOR; AND MEANS FOR APPLYING SAID DEMODULATION SIGNAL TO THE CONTROL ELECTRODE OF AT LEAST ONE OF SAID DEVICES TO EFFECT CONDUCTION IN SAID DEVICES OF SAID MULTIVIBRATOR IN ALTERNATION AND AT THE FREQUENCY OF SAID SUBCARRIER TO DEVELOP IN EACH OF SAID LOAD CIRCUITS OPPOSITE PHASE SIGNALS REPRESENTATIVE OF THE MODULATION COMPONENTS OF SAID SUBCARRIER.