Synchronous detector system

Claim 1

IN A SYSTEM OF COMMUNICATION IN WHICH THE SIDEBANDS OF A RESULTANT WAVE FORMED BY MODULATING IN AMPLITUDE A CARRIER WAVE BY A MODULATING WAVE ARE TRANSMITTED AND IN WHICH SAID MODULATING WAVE IS RECOVERED BY HETERODYNING SAID TRANSMITTED WAVE WITH A LOCALLY GENERATED WAVE IN PHASE WITH SAID CARRIER WAVE AND DERIVING FROM THE HETERODYNED OUTPUT SAID MODULATING WAVE, MEANS FOR MAINTAINING SAID LOCALLY GENERATED WAVE IN PHASE WITH SAID CARRIER WAVE COMPRISING MEANS FOR DERIVING A WAVE IN PHASE QUYADRATURE TO SAID LOCALLY GENERATED WAVE, MEANS FOR MIXING SAID PHASE QUADRATURE WAVE WITH SAID RESULTANT WAVE, MEANS FOR DERIVING FROM THE MIXED OUTPUT A WAVE REPRESENTING THE MODULATING COMPONENT OF SAID RESULTANT WAVE, THE AMPLITUDE AND PHASE OF SAID MODULATING COMPONENT WITH RESPECT TO THE AMPLITUDE AND PHASE OF THE MODULATING COMPONENT DERIVED BY HETERODYNING SAID RESULTANT WAVE WITH SAID LOCALLY GENERATED WAVE VARYING IN ACCORDANC WITH THE DEPARTURE IN PHASE OF SAID LOCALLY GENERATED WAVE FROM THE PHASE OF SAID CARRIERR WAVE, MEANS RESPEONSIVE TO THE POLARITY OF OUTPUT OF SAID PONENTS TO OBTAIN AN OUTPUT WHOSE POLARITY AND MAGNITUDE VARIES RESPECTIVELY IN ACCORDANCE WITH THE DIRECTION AND MAGNITUDE OF THE DEPARTURE OF THE PHASE OF SAID LOCALLY GENERATED WAVE WITH RESPECT TO THE PHASE OF SAID CARRIER WAVE, MEANS RESPONSIVE TO THE POLARITY OF OUTPUT OF SAID COMBINING MEANS TO VARY THE PHASE OF SAID LOCALLY GENERATED WAVE IN INVERSE DIRECTION TO THE DIRECTION OF DEPARTURE OF SAID CARRIER WAVE CAUSING SAID POLARITY THEREBY MAINTAINING SAID LOCALLY GENERATED WAVE IN PHASE WITH SAID CARRIER WAVE.