Phase-sensitive transducer apparatus with 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 being induced 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. The apparatus further comprises means coupled to the winding of the second relatively movable member for squaring the output signal, means coupled to the means for squaring for demodulating the squared output signal to derive a pulse signal of constant peak amplitude and variable pulse width as the first and second relatively movable members are moved relative to one another, means coupled to the means for demodulating for integrating the phase signal to derive a position signal indicative of the relative movement of the first and second relatively rotatable members, the position signal alternating during such relative movement substantially between a supply voltage and a reference voltage, and means coupled to the means for integrating for offsetting the position signal so that it is substantially balanced about the reference voltage.