数字调制谐振式光纤陀螺中阶梯波复位误差的分析

谐振式光纤陀螺(R-FOG)是采用环形谐振腔来增强Sagnac效应的，其检测方案可以分为开环和闭环，在电路实现上，根据相位调制器控制信号的不同，又分为模拟调制和数字调制。相比而言，其数字闭环检测方案具有动态范围大、灵敏度高的特点。在数字调制的谐振式光纤陀螺中，其阶梯波的复位高度V2π是否精确，会对旋转角速度的测量和标度因数的线性度产生影响。从理论上分析了不精确的复位高度V2π对系统的影响，指出不精确的V2π将使谐振腔中的交叉耦合电场和直通耦合电场之间不会形成最佳相消干涉，从而产生误差。利用探测器输出总电场的表达式，以双频率调制的谐振式光纤陀螺为例，对引入的误差作了定量的数值计算，最后给出了克服误差的几种方法。

Analysis of Serrodyne′s Reset Amplitude Errors in Resonator Fiber Optic Gyroscopes by Digital Modulation

Resonator fiber optical gyroscope (R-FOG) uses ring resonator to enhance the Sagnac effect, the detecting methods have open-loop and closed-loop, the phase modulator′s controlling signal has analogous and digital in circuit. Compared with analogous modulation, the method of digital closed-loop detection has a big dynamic range and high sensitivity. In resonator fiber optic gyroscopes by digital modulation, imperfect serrodyne′s reset amplitude V2π has influence on the rotation sensing errors and the scale factor non-linearity. The effects of imperfect V2π on the system are analyzed theoretically. If the amplitude is not exactly V2π, two electric fields, Ecross and Ebar cannot result in optimum destructive interference, thus the resulting waveform has errors. Based on the sum of electric fields expression in detector, numerical calculations of rotation sensing errors associated with imperfect serrodyne amplitude are given for resonator fiber optical gyro using two frequencies modulation. At last, some solutions for substantially reducing errors are presented.