基于快速傅里叶变换的分布式振动传感信号解调分析  

Demodulation Analysis of Distributed Vibration Sensor Signals Based on Fast Fourier Transform

作　　者：司召鹏 毛邦宁 卜泽华 龚华平 徐贲 康娟 杨春君 赵春柳 Si Zhaopeng;Mao Bangning;Bu Zehua;Gong Huaping;Xu Ben;Kang Juan;Yang Chunjun;Zhao Chunliu(College of Optics and Electronic Science and Technology,China Jiliang University,Hangzhou 310018,Zhejiang,China;Hangzhou National Camera Testing Technology Co.,Ltd.,Hangzhou 310012,Zhejiang,China)

机构地区：[1]中国计量大学光学与电子科技学院,浙江杭州310018 [2]杭州国照检测技术有限公司,浙江杭州310012

出　　处：《中国激光》2023年第5期100-106,共7页Chinese Journal of Lasers

基　　金：国家重点研发计划(2020YFF0217803,2020YFF0217800)。

摘　　要：提出了一种在光纤距离方向作快速傅里叶变换(FFT)的振动信号相位提取方法,并在分布式声波传感(DAS)系统上加载200 Hz正弦信号进行了验证。该方法在振动传感光纤距离方向上采用分距离滑动FFT变换提取载波信号的相位,然后对光纤方向缠绕的相位信号进行差分,进而在光纤方向与时间方向上进行解缠绕处理,最后对解缠绕信号进行高通滤波。与DAS系统信号解调常用的IQ解调、希尔伯特变换解调相比,该方式提取的200 Hz振动信号的信噪比为36.71 dB,比IQ、希尔伯特变换提取的信噪比分别高21.04 dB和20.91 dB,且FFT提取的振动相位信号的周期性好,无谐波及低频噪声干扰。对2000 Hz和5000 Hz正弦振动信号的提取结果也表明该方式具有较好的适用性。Objective Phasesensitive optical timedomain reflectometry is a type of distributed optical fiber sensing technology that has become one of the most rapidly developing sensing methods in modern sensing technology because of its wide monitoring range,high sensitivity,low monitoring cost,and many measuring parameters.Compared with other distributed optical fiber sensing technologies,this technology can perform distributed multipoint measurement of weak signals over long distances.Distributed acoustic sensing(DAS)technology uses coherent Rayleigh backscattering technology in common singlemode sensing fibers that can realize the continuous detection of remote external vibration,sound,and temperature changes.This technology has strong environmental applicability,electromagnetic interference resistance,chemical corrosion resistance,and good concealment.Therefore,research on the DAS technology of a phase sensitive optical time domain reflectometer(φ-OTDR)system has great scientific and practical significance for social engineering applications.A DAS system typically adopts IQ and Hilbert demodulation,but both have certain defects.Although the IQ demodulation method has a simple structure,its demodulation results are easily affected by phase noise caused by the frequency drift of narrow linewidth laser and polarization instability of local light and Rayleigh scattering light,decreasing the demodulation accuracy.Hilbert transform can be used in DVS and DAS systems,but the low noise term cannot be eliminated in low pass filtering;therefore,the antinoise performance is poor.In order to address the limitations of IQ and Hilbert transform demodulation methods,a signal demodulation method based on fast Fourier transform(FFT)is adopted in this study to improve the signaltonoise ratio of vibration signals and to reduce the interference of low frequency noise,pulse optical coherence fading,and harmonics.Methods The digital signal collected by the acquisition card is first passed through a belt pass filter such that the signal fre

关 键 词：遥感 傅里叶光学 快速傅里叶变换 扰动检测 信号调制 信噪比 

分 类 号：O436[机械工程—光学工程]