针对低信噪比激光多普勒信号的位移解算,提出了一种基于正弦曲线拟合的多普勒信号相位分析算法.分析了参考光和被测光相位差与光电探测器输出电流之间的关系,推导了正弦曲线拟合算法求解差频信号相位的公式,分别利用传统Hilbert变换和正弦曲线拟合算法,针对不同信噪比多普勒信号进行仿真对比实验.研究结果表明:当信号存在偏置或在低信噪比的条件下,正弦曲线拟合算法比Hilbert变换解算精度高,且当信噪比小于-5 dB时,Hilbert算法误差较大,而正弦函数拟合算法的误差小于1..基于正弦函数拟合的多普勒信号相位分析算法对噪声容忍度更高.%All fiber displacement interferometer system for any reflector (AFDISAR) provides outstanding measurement accuracy and resolution for recording the dynamic damage evolution and fracture of materials in the shock wave and detonation physics research.Based on sine curve fitting,a new numerical phase demodulation method is presented for the low SNR AFDISAR Doppler signal while measuring low speed moving target.The phase difference between reference and measurement beam is determined by the displacement of the measurement target and changes the output current of the photo-detector.Sine curve fitting method is introduced to modulate the phase from the differential frequency of Doppler signal.Traditional Hilbert transform and new sine curve fitting method are simulated separately for modulating the displacement from the low SNR laser Doppler signals with DC-bias offset.The simulation results show that the decoding accuracy of sine curve fitting method is better than the accuracy of Hilbert transform.When SNR decreases to-5 dB,the error of sine curve fitting is only 1°,while the value for Hilbert transform is large.The measurement results show that sine curve fitting method has better robustness and tolerance to noise.
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