Stabilized transducer system for measuring displacement and acceleration

Claim 1

A TRANSDUCER SYSTEM COMPRISING: A RADIO FREQUENCY OSCILLATOR HAVING A TANK CIRCUIT INCLUDING AN INDUCTIVE COIL FOR DEVELOPING A RADIO FREQUENCY OSCILLATOR OUTPUT SIGNAL; A CONDUCTIVE ELEMENT SUSPENDED FOR LIMITED MOTION WHEN SUBJECTED TO AN EXTERNALLY APPLIED FORCE, SAID CONDUCTIVE ELEMENT AND SAID INDUCTIVE COIL BEING DISPOSED IN COUPLING PROXIMITY WITH ONE ANOTHER SO THAT A CHANGE OF POSITION OF SAID CONDUCTIVE ELEMENT INDUCES A CHANGE OF THE LOSS REFLECTED INTO SAID OSCILLATOR TO THEREBY CHANGE THE AMPLITUDE OF THE OSCILLATOR OUTPUT SIGNAL; RECTIFIER MEANS RESPONSIVE TO SAID OSCILLATOR OUTPUT SIGNAL FOR DEVELOPING A RECTIFIED OUTPUT SIGNAL; RESTORING MEANS, CONNECTED TO SAID CONDUCTIVE ELEMENT AND RESPONSIVE TO SAID RECTIFIER OUTPUT SIGNAL, TO APPLY A RESTORING FORCE TO SAID CONDUCTIVE ELEMENT TO BALANCE THE EXTERNALLY APPLIED FORCE; A FEEDBACK CIRCUIT RESPONSIVE TO SAID RECTIFIED OUTPUT SIGNAL FOR DEVELOPING AND APPLYING A NEGATIVE FEEDBACK SIGNAL TO SAID OSCILLATOR TO MAINTAIN THE TRANSFER FUNCTION OF SAID TRANSDUCER SYSTEM CONSTANT, SAID FEEDBACK CIRCUIT INCLUDING A DIRECT-CURRENT PATH AND A PHASE COMPENSATING CIRCUIT TO PROVIDE A PHASE LEAD OF THE FEEDBACK SIGNAL WITH RESPECT TO SAID RECTIFIED OUTPUT SIGNAL; AND MEANS RESPONSIVE TO SAID RECTIFIED OUTPUT SIGNAL TO INDICATE THE MAGNITUDE AND DIRECTION OF THE RESTORING FORCE TENDING TO BALANCE SAID CONDUCTIVE ELEMENT.