Scale factor nonlinearity in an open loop Fiber Optic Gyroscope (FOG) indicates the maximum inaccuracy of rotation rates within the whole measurement range. Because of the non-linearity of the phase modulation, scale factor non-linearity of open loop FOG is inherent and will become worse if the bandwidth of preamplifier is limited. This paper educed theoretically the facts that will make the nonlinearity of scale factor even worse when all harmonic components are amplified dissimilarly. Finally, experiment indicates that 20 multiples of the base frequency bandwidth of a preamplifier with a 1 st-order RC low-pass filter is needed if scale factor nonlinearity we wanted is less than 500 ppm or better%标度因数非线性反应了光纤陀螺在动态范围内输出的偏差度.在开环光纤陀螺中,由于相位调制存在非线性会影响标度因数的线性性.加之前放带宽有限,会使标度因数非线性现象进一步恶化.本文理论分析了,由于滤波器对各次谐波增益不一致,造成标度因数线性度恶化的各种因素.实验结果表明,要使标度因数非线性度小于500ppm,如前放采用一阶RC低通滤波器,前放带宽需大于调制信号基频的20倍.
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