基于φ-OTDR的分布式光纤声波传感系统性能改进研究

Research on Performance improvement of distributed fiber acoustic sensing System based on φ-OTDR

摘要:

基于相敏光时域反射仪(φ-OTDR)的分布式光纤声波传感系统的关键性能之间相互制约，且存在衰落问题，这严重降低了系统的可靠性。为了满足复杂的工程现场环境对φ-OTDR的各性能指标的需求，提出基于自适应卡尔曼滤波(AKF)和频分复用(FDM)的高性能φ-OTDR，利用FDM提升系统的频响带宽，引入自适应卡尔曼滤波对线性响应于外界振动的相位状态的噪声统计特性进行实时估计和修正，抑制了衰落和串扰导致的相位失真问题。实验结果表明，改进后φ-OTDR系统的传感线性度被有效提升，系统本底噪声降低到-83.7 dB2/Hz，应变分辨率达到了0.28 pε/√Hz。

Abstract:

The key performance of distributed fiber acoustic wave sensing system based on phase-sensitive optical time-domain reflectometer (φ-OTDR) is mutually restricted, and there is a fading problem, which seriously reduces the reliability of the system. In order to meet the requirements of performance indexes of φ-OTDR in complex engineering field environment, a high-performance φ-OTDR based on Adaptive Kalman filter (AKF) and frequency division multiplexing (FDM) is proposed to improve the frequency response bandwidth, sensing linearity and strain resolution of the system. The experimental results show that, on the basis of improving frequency response bandwidth of FDM, AKF is used to estimate and correct the statistical characteristics of phase noise linearly responding to external vibration in real time, effectively suppressing the phase distortion caused by fading and crosstalk noise. The sensor linearity of the system is improved, the background noise of the system is reduced from -68.4 dB^2/Hz to -83.7 dB^2/Hz, and the strain resolution is reduced from 1.7 pε/√Hz to 0.28 pε/√Hz.