分布式声波传感系统中IQ解调方法的影响因素  

Influencing Factors of IQ Demodulation Method in Distributed Acoustic Sensors

作　　者：赵丽娟[1,2,3] 张旭哲 徐志钮 陈永辉[1] Zhao Lijuan;Zhang Xuzhe;Xu Zhiniu;Chen Yonghui(School of Electrical and Electronic Engineering,North China Electric Power University,Baoding 071003,Hebei,China;Hebei Key Laboratory of Power Internet of Things Technology,North China Electric Power University,Baoding 071003,Hebei,China;Baoding Key Laboratory of Optical Fiber Sensing and Optical Communication Technology,North China Electric Power University,Baoding 071003,Hebei,China)

机构地区：[1]华北电力大学电气与电子工程学院,河北保定071003 [2]华北电力大学河北省电力物联网技术重点实验室,河北保定071003 [3]华北电力大学保定市光纤传感与光通信技术重点实验室,河北保定071003

出　　处：《光学学报》2023年第14期276-291,共16页Acta Optica Sinica

基　　金：国家自然科学基金(62171185,62273146);河北省自然科学基金(E2020502010);河北省省级科技计划(SZX2020034)。

摘　　要：为了获得相关因素对基于相干探测相敏光时域反射计(φ-OTDR)的分布式声波传感(DAS)系统测量准确性的影响规律,根据光纤中后向瑞利散射理论建立相干探测φ-OTDR仿真模型。基于该模型生成不同测量参数下的后向瑞利散射信号,采用IQ解调算法确定了振动位置、还原了振动信号,计算了振动检测信噪比和失真度。结果表明:采样率可以小于声光调制器(AOM)频率的2倍;宽范围内随着采样率的提高,振动检测信噪比与失真度不是严格单调增加或降低;模数转换器(ADC)量化位数在8~16位范围内变化时对系统解调结果的影响不大;随着入射光脉冲宽度减小、振动点与入射端距离增加,振动检测信噪比分别呈双指数、线性规律下降,失真度分别呈双指数、幂函数规律增加;随着掺铒光纤放大器(EDFA)放大倍数提高,振动检测信噪比呈幂函数规律提升,失真度在高、低噪声时分别呈幂函数、双指数规律下降。Objective Distributed acoustic sensor(DAS)is an optical instrument that employs optical fibers as sensors to detect acoustic vibrations.DAS based on phasesensitive optical timedomain reflectometry(φOTDR)have been widely applied in various fields,such as perimeter security,pipeline monitoring,geological exploration,and transportation due to their strong antiinterference ability,high sensitivity,long sensing distance,and distributed measurement capability.Currently,research onφOTDR systems mainly focuses on system performance optimization,noise reduction,and improvement of pattern recognition efficiency.In addition to the system structures and algorithms,the selection of key parameters in theφOTDR system also exerts a significant impact on the demodulation performance of the system.How to achieve the best performance of the system based on existing hardware,or how to set appropriate parameters according to specific usage scenarios,is also a problem to be addressed.We study the effects of sampling rate,number of analog to digital converter(ADC)bits,pulse width,magnification of erbiumdoped fiber amplifier(EDFA),and vibration positions on the demodulation results of theφOTDR system,and quantitatively evaluate the influence of different influential factors on the system performance.Methods To determine the effect of relevant factors on the measurement accuracy of a DAS system based on coherent detectionφ-OTDR,we build a simulation model of coherent detectionφ-OTDR based on the theory of Rayleigh backscattering in optical fibers.Then vibrational excitation is applied and the corresponding Rayleigh backscattering signals are numerically generated.The vibration information in the fiber is obtained by the IQ demodulation algorithm,and the results of the simulation model are consistent with the theory of coherent detectionφ-OTDR system.Based on the built corresponding DAS experimental system,the measurement results show that both the RBS signal and the waveform of the demodulated vibration signal obtained from the ex

关 键 词：传感器 分布式声波传感器 Φ-OTDR IQ解调 振动检测 影响因素 

分 类 号：TP212[自动化与计算机技术—检测技术与自动化装置]