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为了降低布里渊后向散射光不稳定的偏振态以及系统噪声对分布式光纤温度应变传感系统测量精度的影响,进一步提高测量温度、应变的精度和系统信噪比,提出在该系统中加入扰偏器,以减小系统误差;同时应用小波去噪的方式降低信号的噪声。选用体积和插入损耗都较小的PolaRITETMⅢPSM-001扰偏器。小波去噪过程选用db5小波,经过离散小波变换函数wavedec对信号进行小波分解,选用thselect函数实现阈值获取,选用waverec函数实现信号小波重构。实验证明扰偏器能使系统误差降低到原来的1/3,小波去噪使系统信噪比从原来的26.6dB提高到38.5dB。
In order to reduce the impact of the Brillouin backscattering unstable polarization state and the system noise on the measurement accuracy of the distributed optical fiber temperature and strain sensing system and to further improve the measurement temperature and strain accuracy and the system signal to noise ratio, Add scrambler to reduce the system error; at the same time, using wavelet denoising method to reduce the signal noise. PolaRITETMⅢPSM-001 scrambler with small volume and insertion loss is selected. Wavelet denoising process using db5 wavelet, discrete wavelet transform function wavedec wavelet decomposition of the signal, the thselect function used to achieve the threshold, the use of waverec function to signal wavelet reconstruction. Experimental results show that the scrambler can reduce the systematic error to 1/3, and the wavelet denoising makes the system SNR increase from the original 26.6dB to 38.5dB.