方波调制误差对光纤陀螺的影响分析与实验

Analyses and experiments of effects of square wave modulation errors on fiber optic gyroscope

根据数字闭环光纤陀螺的方波调制、解调原理,指出调制方波的频率、相位和占空比不理想是造成方波调制误差的原因。讨论了周期脉冲干扰的频率和相位特征,利用周期脉冲干扰的傅里叶级数推导出了方波调制误差的数学模型。建立了带有方波调制误差的闭环光纤陀螺简化模型,推导出了方波调制误差和陀螺输出偏置误差的关系。通过仿真和测试分析了调制方波的周期、相位、占空比、光纤环的群延时以及放大电路的增益带宽对陀螺输出偏置的影响。最后,给出了一种利用周期脉冲干扰波形检测方波调制误差的简易方法。

It is isindicated that square wave modulation errors are caused by non-ideal frequency, phase and duty cycle of the square wave based on the principle of square wave modulation and demodulation in digital closed-loop Fiber Optic Gyroscope （FOG）. The frequency and phase characters of the periodic pulse interference were discussed. Meanwhile, the mathematical model of square wave modulation errors were formulated by applying Fourier series of the periodic pulse interference. A simplified model of closed-loop FOG with the square wave modulation errors was developed, and a relational expression between the square wave modulation errors and the bias error of closed-loop FOG was obtained. The effects of the square wave cycle, phase, duty cycle and the fiber coil group delay and amplifier gain bandwidth on the bias error of closed-loop FOG were analyzed by simulating and testing. A simple method was presented to detect the square wave modulation errors via the waveform of the periodic pulse interference.