摘要
基于相位敏感光时域反射计(Φ-OTDR)的分布式光纤振动传感系统在铁路周界安防中有着重要的应用前景.为降低Φ-OTDR中固有的相干衰落对相位解调的影响,提高扰动信号识别率,提出一种基于矢量旋转滑动平均(MVRA)的相干衰落抑制方法.首先,对探测信号复矢量化,并对各位置的复矢量信号按初相角进行旋转对齐;然后,采用滑动平均的方法缓和信号幅度起伏以及减小噪声功率,提高信噪比,进而抑制相干衰落;其次,从衰落抑制信号解调出扰动信号,将MVRA与频谱提取重组(SERM)、数字向移变换(DPST)方法进行对比,通过差分相位标准差验证抗衰落效果;最后,通过搭建分布式光纤周界入侵检测实验平台,模拟环境噪声、应力破坏、攀爬、剪网4种防护扰动信号,以解调的相位灰度图作为特征图像,使用卷积神经网络进行模式识别.实验结果表明:相比SERM、DPST,MVRA能更高效地抑制衰落,当滑动窗长50 ns时,MVRA提高11.2 dB信噪比;扰动信号的识别率由衰落抑制前的88%提高到衰落抑制后的92%.
Distributed optical fiber vibration sensor based on phase-sensitive optical time-domain reflectometry(Φ-OTDR)has important application prospects in railway perimeter security.In order to reduce the influence of inherent interference fading inΦ-OTDR on phase demodulation and improve the recognition rate of disturbance signals,an interference fading suppression method based on moving vector rotating average(MVRA)was proposed.Firstly,the detected signal was characterized by a complex vector,and the complex vector signals at each position were rotated and aligned according to their initial phase angles.Then,the moving average method was used to improve the signal-to-noise ratio by mitigating the fluctuation of the signal amplitude and reducing the power of the detected noise,thereby suppressing interference fading.Next,the disturbance signal was demodulated from the suppressed fading signal.MVRA was compared with spectrum extraction and remix(SERM)and digital phase-shift transform(DPST)methods,and the anti-fading effect was verified by the standard deviation of the differential phase.Finally,an experimental platform for distributed optical fiber perimeter intrusion detection was built to simulate four kinds of protective disturbance signals,including environmental noise,stress damage,climbing,and net shearing.The demodulated phase grayscale image was taken as the feature image,and then a convolutional neural network was used for pattern recognition.The experimental results show that MVRA can suppress fading more efficiently than SERM and DPST.When the sliding window length is 50 ns,the signal-to-noise ratio is improved by 11.2 dB,and the recognition rate of disturbance signals is increased from 88%before fading suppression to 92%after fading suppression.
作者
胡祖翰
钱恒
石先明
刘利平
徐余明
罗斌
HU Zuhan;QIAN Heng;SHI Xianming;LIU Liping;XU Yuming;LUO Bin(China Railway Siyuan Survey and Design Group Co.,Ltd.,Wuhan 430063,China;School of Information Science and Technology,Southwest Jiaotong University,Chengdu 611756,China)
出处
《西南交通大学学报》
EI
CSCD
北大核心
2024年第3期564-571,共8页
Journal of Southwest Jiaotong University
基金
国家自然科学基金(61735015)。
关键词
相位敏感光时域反射计
相干衰落
周界安防
phase-sensitive optical time-domain reflectometry
interference fading
perimeter security
