Real-time Estimation Method of Normalized Parameter for PGC Demodulation of Optical Fiber Hydrophone
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摘要: 针对光纤水听器相位生成载波(PGC)相位解调中采用离线估计归一化参数进行处理带来的明显失真, 提出了一种归一化参数实时估计方法。该方法通过先计算2路正交信号目前时间点信号幅度与前一时间点信号幅度平方差, 再计算两者比值得到归一化参数。通过仿真结合试验测量, 验证了该方法可以在较小信号幅度情况下实现准确的归一化参数估计。试验结果表明, 当光纤水听器上施加峰值为0.3 rad的信号时, 采用实时估计的归一化参数值估计误差小于3%, 用该值进行光纤水听器信号解调处理, 得到的信号与总谐波失真比优于48 dB, 可满足工程化应用需要。Abstract: A real-time estimation method of normalized parameter is proposed to reduce the significant distortion in phase generated carrier(PGC) demodulation of optical fiber hydrophone due to offline estimation of normalized pa-rameter. The square differences of the amplitudes of two orthogonal signals at both current time point and previous time point are calculated, then the normalized parameter is obtained by calculating the ratio of two square differences. Simu-lations and experiments show that a correct normalized parameter can be achieved with the proposed method if signal amplitude is small. Experimental results indicate that when a small signal with peak amplitude of 0.3 radian is imposed to the hydrophone, the estimation error of normalized parameter gets less than 3%. Using the achieved normalized pa-rameter to demodulate the signal of the optical fiber hydrophone, signal to total harmonic distortion ratio is less than 48 dB, which meets the requirement for engineering application.
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