Plural signal frequency detector able to continuously distinguish whether frequency difference is positive or negative

Claim 1

IN A CIRCUIT ADAPTED TO ENABLE THE DETERMINATION TO BE MADE, IN A CONTINUOUS MANNER, OF THE SIGN OF A DIFFERENCE BETWEEN TWO QUANTITIES REPRESENTED BY THE FREQUENCY OF TWO CONTINUOUS WAVES, ONE SAID CONTINUOUS WAVE BEING MODULATED BY AN AUXILIARY SIGNAL, MEANS TO GENERATE WAVES AT DIFFERENT FREQUENCIES AND MEANS TO GENERATE AN AUXILIARY SIGNAL, A PHASE-DETECTOR CIRCUIT RECEIVING THE WAVES AND AUXILIARY SIGNAL FROM BOTH SAID MEANS AND SUPPLYING SIGNALS TO TWO FILTERS, ONE SAID FILTER BEING TUNED AT THE BEAT FREQUENCY OF SAID TWO CONTINUOUS WAVES AND THE OTHER SAID FILTER BEING TUNED AT THE FREQUENCY OF SAID AUXILIARY SIGNAL, TWO GATE UNITS OF THE "AND" TYPE WHICH RECEIVE AND COMPARE THE PHASE OF THE SIGNAL FROM THE SAID FILTER WHICH IS TUNED AT THE FREQUENCY OF THE AUXILIARY SIGNAL WITH THE PHASE OF THE AUXILIARY SIGNAL, TWO SHAPING CIRCUITS WHICH RECEIVE, AS INPUT, THE OUTPUT FROM THE SAID BEAT FREQUENCY FILTER AND SHAPE SAID INPUT INTO A CONTROL SIGNAL FOR OPERATING SAID TWO GATE UNITS.