Patent ID: 6415237
Filing Date: 2002-07-02
Classification: G01D

Abstract:
A method of correcting spin frequency noise error in the output of a rotary displacement transducer having a known resolution, comprising the steps of:for each revolution of the transducer, storing a series of output values, each output value representing a time interval between pulses of the transducer; calculating an inphase value by multiplying each output value times a sin wave value, the sin wave having a period determined by the transducer resolution, and by calculating an average from the results of the multiplying step; calculating a quadrature value by multiplying each output value times a cosine wave value, the cosine wave having a period determined by the transducer resolution, and by calculating an average from the results of the multiplying step; calculating a magnitude and a phase value from the inphase and quadrature values; calculating a series of correction values, the correction values corresponding to points on a sin wave having a period determined by the transducer resolution and having a magnitude and phase equal to the magnitude and phase values; subtracting each correction value from a corresponding transducer output value, thereby providing corrected transducer output values; and repeating the above steps for a next revolution of the transducer.