High resolution signal processing of mechanically dithered ring laser gyro

Two beat frequency signals with /2 phase difference are generated in mechanically dithered ring laser gyro (MDRLG). Usually the fourfold frequency counting signals are acquired when demodulating the two output signals. Finite impulse response (FIR) filtering and dither stripping are used to eliminate dither signal from the counting signals and obtain the angular rate of MDRLG. The analog beat frequency signals of MDRLG are sampled at a high speed and then subdivided into 16 beat frequency signals with /16 phase difference alternately. The mean square deviation of the output angular rate is reduced and the high resolution signal processing is realized by increasing the counting pulses of MDRLG. Allan variance analysis of experiment results shows that the quantization error is reduced from 0.327 to 0.170 by increasing multiplication. Since the quantization error is the main error source when removing the dither signal of MDRLG, the accuracy of MDRLG is improved effectively by the high resolution signal processing.