分布式光纤温度应变传感系统性能改进研究

Research on Performance Improvement of Distributed Optical Fiber Temperature and Strain Sensing System

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 effect of unstable polarization state of the backward Brillouin scattering light and system noise on the measurement accuracy of the distributed optical fiber temperature and strain sensing system and further improve the accuracy of temperature and strain measurement and noise ratio of the system, a polarization scrambler was applied on the system to reduce systematic errors. And the wavelet denoising method was proposed to reduce the signal noise. The polarization scrambler with the model of PolaRITETM Ⅲ PSM-001 of General Photonics company was used for the smaller volume and insertion loss. ＂db5＂ wavelet was selected for denoising and the discrete wavelet transform function ＂wavedec＂ was used for wavelet decomposing with the scale of 5. The threshold was obtained by ＂thselect＂ function and function ＂waverec＂ was used for signal wavelet reconstruction. Experimental results show that the system error is reduced to 1/3 of the original one by the polarization scrambler, and SNR of the system is improved from 26.6 dB without wavelet denoising up to 38.5 dB by applying wavelet denoising.