基于FPGA的Φ-OTDR系统数字正交解调方法  

Φ-OTDR system digital quadrature demodulation method based on FPGA

作　　者：李沛峰 刘丽 王宇 刘昕 白清 靳宝全 Li Peifeng;Liu Li;Wang Yu;Liu Xin;Bai Qing;Jin Baoquan(Key Laboratory of Advanced Transducers and Intelligent Control System of Ministry of Education and Shanxi Province,Taiyuan University of Technology,Taiyuan 030024,China)

机构地区：[1]太原理工大学新型传感器与智能控制教育部与山西省重点实验室,太原030024

出　　处：《电子测量与仪器学报》2024年第5期19-28,共10页Journal of Electronic Measurement and Instrumentation

基　　金：国家自然科学基金(62175175);山西省重点研发计划项目(202102130501021);中央引导地方科技发展资金项目(YDZJSX20231B004);山西省科技创新团队项目(201805D131003)资助。

摘　　要：相位敏感光时域反射仪(Φ-OTDR)通常利用相干探测的方式实现长距离、分布式、高灵敏度的振动检测。为了准确获取振动信号的位置与相位信息,正交解调算法是当下广泛使用的重要技术,但该算法存在耗时过长的局限。针对此问题,提出了一种基于现场可编程门阵列(FPGA)的瑞利散射信号快速解调方案,采用流水线结构实现传感数据采集以及数据解调的同步,通过数字正交混频技术获取两路正交信号,利用有限冲激响应低通滤波去除高频分量,利用坐标旋转数字算法(CORDIC)向量模式实现振动相位硬件解调,可以较好地提升相干探测Φ-OTDR系统整体的实时性。实验结果表明,在探测距离40 km的条件下,传感系统可成功实现振动信号的定位与相位还原。而探测距离不变,数据采集条数提升至4 000条时,FPGA解调仅耗时1.60 s,与传统的上位机CPU解调方案相比缩短了145.61 s,从而为Φ-OTDR振动传感数据的实时解调提供了参考。Phase-sensitive optical time domain reflectometer(Φ-OTDR)usually uses coherent detection to achieve long-distance,distributed and high-sensitivity vibration detection.To accurately obtain the position and phase information of the vibration signal,the quadrature demodulation algorithm is an important technology widely used at present,but the algorithm has the limitation of timeconsuming.In order to solve this problem,a fast demodulation scheme of Rayleigh scattering signal based on field programmable gate array(FPGA)is proposed.The pipeline structure is used to realize the synchronization of sensor data acquisition and data demodulation.Two orthogonal signals are obtained by digital quadrature mixing technology.The finite impulse response low-pass filter is used to remove the high-frequency component,and the coordinate rotation digital algorithm(CORDIC)vector mode is used to realize the hardware demodulation of the vibration phase,which can improve the overall real-time performance of the coherent detectionΦ-OTDR system.The experimental results show that the scheme can successfully realize the positioning and phase reduction of the vibration signal under the condition of a detection distance of 40 kilometer.When the detection distance unchanged and the pieces of data acquisition increased to 4000,the FPGA demodulation scheme only takes 1.60 seconds,which is 145.61 seconds shorter than the traditional host computer CPU demodulation scheme,thus providing a reference for the real-time demodulation ofΦ-OTDR vibration sensing data.

关 键 词：光纤传感 相位敏感光时域反射仪 现场可编程门阵列 坐标旋转数字算法 

分 类 号：TP212.1[自动化与计算机技术—检测技术与自动化装置]