High frequency impedance bridge utilizing an impedance standard that operates at a low frequency

Claim 1

A MEASUREMENT CIRCUIT COMPRISING: A SOURCE OF TRIGGER SIGNALS; FIRST AND SECOND SAMPLERS, EACH HAVING A SIGNAL INPUT AND A TRIGGER INPUT AND BEING CONNECTED TO RECEIVE SAID TRIGGER SIGNALS AT SAID TRIGGER INPUT FOR PRODUCING AN OUTPUT SIGNAL HAVING AN AMPLITUDE RELATED TO THE AMPLITUDE OF A SIGNAL ON SAID SIGNAL INPUT AT EACH OCCURRENCE OF A TRIGGER SIGNAL; A SOURCE OF TEST SIGNAL; MEANS CONNECTED TO SAID SOURCE OF TEST SIGNAL FOR APPLYING THE TEST SIGNAL TO THE ELEMENT UNDER TEST AND TO THE SIGNAL INPUT OF THE FIRST SAMPLER; MEANS CONNECTED TO THE SIGNAL INPUT OF THE SECOND SAMPLER FO/R APPLYING THERETO THE SIGNAL APPEARING ACROSS THE ELEMENT UNDER TEST; A SOURCE OF REFERENCE FREQUENCY; MEANS CONNECTED TO SAID SOURCE OF REFERENCE FREQUENCY AND TO THE OUTPUT OF ONE OF THE FIRST AND SECOND SAMPLERS FOR PRODUCING A CONTROL SIGNAL RELATED TO THE PHASE RELATIONSHIP BETWEEN THE REFERENCE FREQUENCY AND A SELECTED FREQUENCY COMPONENT OF THE VARIATIONS IN AMPLITUDE OF THE SIGNAL AT THE OUTPUT OF SAID ONE OF THE SAMPLERS; MEANS TO SUPPLY SAID CONTROL SIGNAL TO THE SOURCE OF TRIGGER SIGNALS FOR ALTERING THE REPETITION RATE THEREOF; AN IMPEDANCE STANDARD; MEANS CONNECTED TO THE OUTPUT OF AT LEAST ONE OF SAID SAMPLERS FOR APPLYING THE SIGNAL APPEARING THEREON TO SAID IMPEDANCE STANDARD; AND MEANS CONNECTED TO SAID IMPEDANCE STANDARD FOR PROVIDING AN INDICATION RELATED TO THE SIGNAL APPEARING THEREACROSS.