基于卡尔曼滤波的光纤压力信号解调方法

A Demodulation Method of Optical Fiber Pressure Signal Based on Kalman Filtering

针对光纤法布里-珀罗传感系统长时间运行时,数据采集等电路部分热噪声过大,造成压力信号相位解调误差过大的问题,建立了基于卡尔曼滤波算法的压力解调算法模型,使用卡尔曼滤波算法对光纤压力信号进行去噪处理.经过计算,当信噪比为15 dB的情况下相位解调误差低于0.1 rad,标准差缩小1 000倍,不同信噪比下,滤波后的相位解调标准差稳定在0.012~0.026 rad之间,绝对相位拟合直线的截距稳定在75.8~76.7.实验结果表明,经过降噪滤波处理的信号解调出的结果精度明显改善,提高了系统在噪声条件下的解调精度和整体稳定性.

For optical fiber Fabry-Perot （F-P） sensing systems, the thermal noise of circuits will increase after a long time operation, leading to large error of phase demodulation of pressure signal. Regarding this problem, a Kalman filtering based pressure demodulation model is established for the optical fiber F-P sensing system, and the Kalman filtering algorithm is applied to deal with the fiber optic pressure signal. Simulation results show that the phase demodulation accuracy error is lower than 0. 1 rad when signal to noise ratio （SNR） is 15 dB, and that the standard deviation is reduced by 1 000 times. Under different SNRs, the standard deviation of phase demodulation is stable within 0.012-0. 026 rad after filtering, and the fitting linear intercept of absolute phase is stable within 75. 8-76. 7, verifying that the accuracy of the signal demodulation process is improved obviously and can meet the requirements of high precision pressure signal and the system stability.