研究了一种可实现开环光纤陀螺大动态范围测量的正交解调算法。对干涉信号每周期间隔π/6进行直接采样，得到12个离散点进行相位解调，并利用条纹计数方法实现了开环光纤陀螺的大动态范围测量。详细分析了开环光纤陀螺系统相位调制器驱动信号、干涉信号采样相位误差与正交解调算法解调误差之间的关系。利用抽取的12个采样点构建调制深度误差E_M和调制初始相位误差E_W评价参数，并对正弦调制信号参数进行反馈控制，保证解调精度。结果表明，为使开环光纤陀螺的相位解调误差在±10^-6 rad（标度因数为1.134 s，陀螺输出角速度误差为±0.18（°）/h）内，正弦调制信号的调制频率f_e误差需小于±0.072%（97.31 kHz），电压峰峰值V_π误差需小于±0.1%（3.654 V），调制初始相位误差需小于±16.226 mV，调制深度误差需小于±12.483 mV，数字采样相位误差需小于5.625×10^-4 rad。

A quadrature demodulation algorithm for large dynamic range measurement of open-loop fiber optic gyroscope is studied in this paper. The interference signal is directly sampled every π/6 every cycle, and 12 sampling points are obtained for phase demodulation. The large dynamic range measurement of open-loop fiber optic gyroscope is realized by using fringe counting method. The relationship between the sampling phase error of phase modulator driving signal and interference signal of open-loop fiber optic gyroscope system and the demodulation error of quadrature demodulation algorithm is analyzed in detail. The evaluation parameters of modulation depth error E_M and modulation initial phase error E_W are constructed by using the extracted 12 sampling points, and the sinusoidal modulation signal parameters are feedback controlled to ensure the demodulation accuracy. The results show that in order to make the phase demodulation error of open-loop fiber optic gyroscope within ±10^-6 rad (scale factor is 1.134 s, gyro output angular velocity error ±0.18 (°)/h), the error of modulation frequency f_e of sinusoidal modulation signal should be less than ±0.072% (97.31 kHz), and the error of voltage peak to peak V_π should be less than ±0.1% (3.654 V), the modulation initial phase error should be less than ±16.226 mV and the modulation depth error should be less than ±12.483 mV, and the digital sampling phase error should be less than 5.625×10^-4 rad.