针对瑞利散射信号的随机性以及光纤衰减导致分布式光纤传感系统扰动定位困难、事件误报率高的问题,根据瑞利散射曲线的时域相关性,提出了基于滑动窗的相关系数的扰动事件校验与定位算法.该算法根据在发生扰动事件时相邻周期的光时域反射曲线、扰动点及后续位置相关性骤降的特征,在相邻两周期的光时域反射曲线末端设置数据窗并计算相关系数,设定相关系数的阈值校验有无扰动事件发生.若判别存在扰动事件,则向前滑动数据窗并计算相关系数,然后与定位阈值对比从而定位事件.文中搭建了分布式光纤振动传感系统,在 25 km长的光纤范围内实现了±3 m的定位误差、±5 m的空间分辨率,系统响应时间仅为0.15 s.
Research on Distributed Optical Fiber Perturbation Location Algorithm Based on Time Domain Trace Correlation Identification
Aiming at perturbation positioning difficulties and high event false alarm rate in the distributed optical fiber sen-sing system,caused by the randomness of Rayleigh scattering signals and optical fiber attenuation,according to the time domain correlation feature of the Rayleigh scattering traces,the perturbation event verification and location algorithm based on the correla-tion coefficient of the sliding window was proposed.The algorithm was based on the feature that the correlation between two optical time domain reflection traces of neighbouring periods decreased abruptly at the point of perturbation and subsequent positions when a perturbation event occured,and then a data window was set at the end of the optical time domain reflection traces of neighbouring periods,and the correlation coefficient was calculated,and then determines the threshold of the correlation coeffi-cient was determined to check whether a perturbation event occurs.And then,if it distinguished a perturbation event,the setted data window slided forward,and the correlation coefficient was calculated and compared with the positioning threshold to locate the event.In experiment,a distributed optical fiber vibration sensing system was constructed,and the positioning error achieved is±3 m within spatial resolution of±5 m along an optical fiber range of about 25 km,and the system response time is only 0.15 s.
distributed optical fiber sensingperturbation positioningcorrelationRayleigh scatteringoptical time domain reflection
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