Dynamic limiter for stereophonic broadcast receiver

Claim 1

IN A RECEIVING SYSTEM FOR CARRIER SIGNALS MODULATED IN ANGLE AND IN AMPLITUDE WITH STEREOPHONIC SIGNAL INFORMATION, MEANS PROVIDING SEPARATE AMPLITUDE AND ANGLEMODULATION SIGNAL TRANSLATING CHANNELS, AN ELECTRONIC-TUBE GRID-BIAS LIMITER CIRCUIT AND AN ANGLE-MODULATION DETECTOR CIRCUIT COUPLED THEREWITHIN THE ANGLE-MODULATION-CHANNEL, AN AMPLITUDE-MODULATION ENVELOPE DETECTOR CIRCUIT IN THE AMPLITUDE-MODULATION CHANNEL, AND A CONTROL CIRCUIT FOR VARYING THE AMPLITUDE OF THE DETECTED SIGNAL FROM THE ANGLE-MODULATION DETECTOR CIRCUIT AS THE AVERAGE AMPLITUDE OF THE AMPLITUDE-MODULATION DETECTOR CIRCUIT OUTPUT SIGNAL VARIES DUE TO VARIATIONS IN SIGNAL STRENGTH AT SAID DETECTOR CIRCUIT TO MAINTAIN A PREDETERMINED TRACKING RELATION IN THE AMPLITUDES OF THE CHANNEL OUTPUT SIGNALS FOR MATRIXING AND REPRODUCTION IN STEREOPHONIC FORM, SAID LAST NAMED MEANS INCLUDING A DIODE CONNECTED TO CONTROL THE POSITIVE PEAKS OF SIGNALS APPLIED TO THE GRID-BIAS LIMITER CIRCUIT AND TO THE ANGLE-MODULATION DETECTOR CIRCUIT COUPLED THERETO, SAID DIODE HAVING A CATHODE AND HAVING AN ANODE CONNECTED TO THE INPUT GRID OF THE LIMITER AMPLIFIER TUBE, AND MEANS FOR HOLDING SAID CATHODE AT A SIGNAL-VARIABLE NEGATIVE DIRECT-CURRENT CONTROL VOLTAGE WITH RESPECT TO THE CATHODE OF THE TUBE TO CLAMP THE POSITIVE PEAKS OF THE APPLIED SIGNAL AT THE TUBE GRID AT A LEVEL APROXIMATELY THAT OF THE CONTROL VOLTAGE AND LIMIT THE SIGNAL OUTPUT TO THE VARIABLE CONTROL VOLTAGE LEVEL, THEREBY TO EFFECT SAID TRACKING RELATION.