机械抖动激光陀螺的高分辨率信号处理

High resolution signal processing of mechanically dithered ring laser gyro

机械抖动激光陀螺(MDRLG)信号是两路相位差为π/2的正弦拍频信号,一般采用4倍频鉴相输出计数脉冲,利用FIR滤波和抖动剥除等方法解调抖动信号,从而得到外界输入的角速度信息。高速采集MDRLG信号,并细分为相位依次相差π/16的16路信号,实现MDRLG的8倍频、16倍频和32倍频鉴相输出。输出角速率的均方差随着倍频数的提高而减小,信号处理的分辨率得到提高。实验测试和Allan方差分析表明:32倍频时的量化误差Q从4倍频鉴相时的0.327″减小到0.170″,增加MDRLG信号鉴相的倍频数可以减小量化误差。在对MDRLG信号进行抖动剥除解调时,由于量化误差是主要误差源之一,高分辨率信号处理能够有效提高MDRLG角速度测量的精度。

Two beat frequency signals with π/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 π/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.