Phase-sensitive transducer apparatus with improved signal offset means

Abstract

A phase-sensitive transducer apparatus comprises first and second relatively movable members, the first relatively movable member having a plurality of windings and the second relatively movable member having a winding. Means are included for applying a first input signal to one of the windings of the first relatively movable member and a second input signal to another of the windings of the first relatively movable member. An output signal is developed on the winding of the second relatively movable member. The first and second input signals are sinusoidal in nature of substantially identical frequency and peak amplitude and are phase-displaced by a predetermined amount, and the output signal is substantially constant in peak amplitude and variable in phase during relative movement of the first and second relatively movable members. Further means is included which responds to the first input signal and to the output signal for generating a position signal indicative of the relative movement of the first and second relatively movable members, the position signal alternating during such relative movement between first and second voltage levels. Also, additional means is included which responds to the first input signal and to the second input signal for generating a d-c reference signal having a voltage level substantially equal to the voltage level of the position signal when the first input signal and the output signal are phase-displaced by said predetermined amount. Comparator means is included which responds to the position signal and to the d-c reference signal for offsetting the position signal by an amount represented by the voltage level of the d-c reference signal.