Fm stereophonic multiplex receiver having a single stage for frequency doubling of the pilot signal and amplification of the sub-carrier and l-rsignals

Claim 1

IN COMBINATION FOR USE IN A SYSTEM WHEREIN FIRST AND SECOND STEREO SIGNALS REPRESENTING STEREO SOUND ARE ADDED TO OBTAIN A FIRST RESULTANT SIGNAL AND WHEREIN THE FIRST AND SECOND STEREO SIGNAL ARE SUBSTRACTED TO OBTAIN A SECOND RESULTANT SIGNAL AND WHEREIN THE SECOND RESULTANT SIGNALS ARE MODULATED ON A SUPPRESSED SUB-CARRIER AND WHEREIN THE FIRST RESULTANT SIGNALS AND THE MODULATED SECOND RESULTANT SIGNALS AND A PILOT SIGNAL HAVING A HARMONIC RELATIONSHIP TO THE SUB-CARRIER ARE TRANSMITTED IN MODULATED FORM TO A RECEIVER REMOVED FROM THE TRANSMITTER AND WHEREIN STAGES ARE INCLUDED AT THE RECEIVER FOR DEMODULATING THE RECEIVED SIGNALS TO RECOVER THE FIRST RESULTANT SIGNALS AND THE MODULATED SECOND RESULTANT SIGNALS AND THE PILOT SIGNAL, FIRST MEANS RESPONSIVE TO THE PILOT SIGNALS AND THE MODULATED SECOND RESULANT SIGNALS AND HAVING A PASSBAND FOR PASSING SIGNALS ONLY AT THE PILOT FREQUENCY AND IN THE RANGE OF FREQUENCIES CORRESPONDING TO THE MODULATED SECOND RESULTANT SIGNALS, A FIRST SINGLE STAGE INTERCONNECED WITH THE FIRST MEANS AND RESPONSIVE TO THE SIGNALS PASSED BY THE FIRST MEANS FOR CHANGING THE FREQUENCY OF THE PILOT SIGNAL TO PRODUCE SIGNALS AT THE SUB-CARRIER FREQUENCY AND FOR AMPLIFYING THE SIGNALS AT THE SUB-CARRIER FREQUENCY AND THE MODULATED SECOND RESULTANT SIGNALS PASSED BY THE FIRST MEANS TO REMODULATE THE SUB-CARRIER WITH THE MODULATED SECOND RESULTANT SIGNALS, A SECOND SINGLE STAGE INTERCONNECTED WITH THE FIRST SINGLE STAGE AND RESPONSIVE TO THE SIGNALS FROM THE FIRST SINGLE STAGE FOR DETECTING THE REMODULATED SIGNALS FROM THE FIRST SINGLE STAGE TO PRODUCE FIRST AND SECOND CONTROL SIGNALS REPRESENTING THE ENVELOPE OF THE REMODULATED SIGNALS FROM THE FIRST SINGLE STAGE AND HAVING OPPOSITE PHASES AND INDIVIDUALLY REPRESENTING THE SECOND RESULTANT SIGNALS, AND SECOND MEANS INTERCONNECTED WITH THE SECOND SINGLE STAGE AND RESPONSIVE TO THE FIRST AND SECOND CONTROL SIGNALS AND TO THE FIRST RESULTANT SIGNALS FOR INDIVIDUALLY COMBINING THE FIRST RESULTANT SIGNALS WITH THE FIRST CONTROL SIGNALS AND COMBINING THE FIRST RESULTANT SIGNALS WITH THE SECOND CONTROL SIGNALS RESPECTIVELY TO OBTAIN THE FIRST AND SECOND STEREO SIGNALS.