Detector of phase differences between currents of different frequencies

Claim 1

APPARATUS FOR DETERMINING PHASE CHANGES OF A FIRST ALTERNATING CURRENT WAVE OF FREQUENCY F1 WITH RESPECT TO A SECOND ALTERNATING CURRENT WAVE OF FREQUENCY F2 IN WHICH F1 AND F2 ARE DIFFERENT HARMONICS OF A BASE FREQUENCY FB CONSTITUTING THE GREATEST COMMON DIVISOR OF F1 AND F2, SAID APPARATUS COMPRISING: FIRST PULSE-FORMING MEANS RESPONSIVE TO SAID FIRST WAVE FOR GENERATING A FIRST TRAIN OF PULSES SYNCHRONIZED IN FIXED PHASE RELATION WITH SAID FIRST WAVE; SECOND PULSE-FORMING MEANS RESPONSIVE TO SAID SECOND WAVE FOR GENERATING A SECOND TRAIN OF PULSES SYNCHRONIZED IN FIXED PHASE RELATION WITH SAID SECOND WAVE; THE PULSES OF SAID FIRST AND SECOND TRAINS BEING SHARP SPIKES SHORTER THAN THE HALF WAVELENGTH OF EITHER OF SAID WAVES; BISTABLE MEANS CONNECTED TO SAID FIRST AND SECOND PULSEFORMING MEANS AND OPERABLE INTO A FIRST CONDITION IN RESPONSE TO EACH PULSE OF SAID FIRST TRAIN AND INTO A SECOND CONDITION IN RESPONSE TO EACH PULSE OF SAID SECOND TRAIN, SAID BISTABLE MEANS GENERATING OUTPUTS OF EQUAL MAGNITUDES BUT OF OPPOSITE POLARITIES IN SAID FIRST AND SECOND CONDITIONS RESPECTIVELY; FILTER MEANS CONNECTED TO SAID BISTABLE MEANS FOR INTEGRATING THE OUTPUT THEREOF OVER A TIME AT LEAST EQUAL TO THE PERIOD OF SAID BASE FREQUENCY, THE MAGNITUDE OF THE D.C. OUTPUT OF SAID FILTER MEANS VARYING LINEARLY WITH PHASE CHANGE BETWEEN SAID FIRST AND SECOND ALTERNATING WAVES OVER THE PERIOD OF THE CYCLE OF THE LEAST COMMON FREQUENCY OF F1 AND F2.