Rc correlator circuit for synchronous signal detection

Claim 1

A CIRCUIT FOR MIXING A FIRST SIGNAL OF THE FREQUENCY W1T AND PHASE $ WITH A SECOND SIGNAL OF FREQUENCY W1T AND $R AND DEVELOPING THEREFROM AN OUTPUT PROPORTIONAL TO THE INTEGRAL OF THE D.C. COMPONENT OF THE PRODUCT OF SAID FIRST AND SECOND SIGNALS OVER A PREDETERMINED INTERVAL OF TIME T WHERE W1T IS MUCH GREATER THAN UNITY; COMPRISING AMPLIFIER MEANS HAVING ESSENTIALLY INFINITE OUTPUT IMPEDANCE TO WHICH SAID FIRST SIGNAL IS APPLIED AS AN INPUT, THE OUTPUT OF SAID AMPLIFIER MEANS BEING CONNECTED SERIALLY THROUGH A FIRST CAPACITOR AND A FIRST SWITCHING MEANS TO COMMON GROUND, THE OUTPUT OF SAID AMPLIFIER BEING ADDITIONALLY CONNECTED SERIALLY THROUGH A SECOND CAPACITOR AND A SECOND SWITCHING MEANS TO COMMON GROUND, MEANS FOR ALTERNATELY CLOSING EACH OF SAID FIRST AND SECOND SWITCHING MEANS FOR PREDETERMINED TIME INTERVALS CORRESPONDING TO HALF CYCLE PERIODS OF TIME AT THE FREQUENCY W1T, AN OUTPUT TAKEN ACROSS SAID SECOND SWITCHING MEANS, SAID OUTPUT BEING EQUAL TO THE CHARGE ACROSS SAID FIRST AND SECOND CAPACITORS AT A PERIOD OF THE TIME WHEN SAID SECOND SWITCHING MEANS IS OPEN AND SAID FIRST SWITCHING MEANS IS CLOSED, AND BEING PROPORTIONAL TO THE INTEGRAL OF THE D.C. COMPONENT OF THE PRODUCTS OF SAID FIRST AND SECOND INPUT SIGNALS AT THE END OF SAID PERIOD OF TIME T.