基于相位敏感光时域反射计的多功能光纤安防系统实用化技术研究

发布时间：2018-10-29 12:50

【摘要】：分布式光纤传技术是将光纤同时作为传输和传感介质的一种传感技术，能对待测参量进行远程实时监测。基于分布式光纤传感的周界安防系统是新一代安防系统，与传统机电类安防系统相比，具有灵敏度高、体积小、重量轻、抗电磁辐射能力强等优点，可应用于多种恶劣环境。普通分布式光纤安防系统，例如基于M-Z、Sagnac等干涉型光纤传感系统，通常只能实现单点检测。为实现多入侵点的同时检测和定位，本文开展了基于相位敏感光时域反射计(Φ-OTDR)的多功能光纤安防系统研究。作为一种新型安防检测系统，其不仅具备多点入侵同时检测和定位能力，而且具有隐蔽性好，定位精确，适宜长距离大范围监测等优点，在安防领域有着广阔的应用前景。本文对基于Φ-OTDR的多功能光纤安防系统的实用化技术进行研究，主要工作分以下几方面： (1)分别讲述了基于OTDR和基于干涉仪原理的分布式光纤传感技术的研究现状，并比较了两种传感技术的差异；深入分析了结合OTDR和干涉原理的Φ-OTDR系统所具有的独特优势和发展前景。 (2)介绍了光纤中的光散射现象，分析了Φ-OTDR系统的检测和定位原理，，结合光纤后向散射离散模型和蒙特卡罗方法对系统进行了理论分析和仿真模拟。 (3)研究了激光器线宽、累加平均次数、脉冲宽度以及入侵信号对系统性能的影响。首先，发现了噪声随累加平均次数增加而呈现出先快后慢的衰减趋势，信噪比随脉冲宽度的增大而先增后减的规律。然后，研究得出信噪比和定位精度随入侵信号相位呈周期性的变化规律，以及入侵信号频率对系统漏报率的影响。最后，针对系统中存在的一些缺陷提出了初步的解决方案并进行了实验研究。 (4)搭建了一套多功能光纤安防系统，研究了系统中各器件的参数和选型要求，进行了多点入侵检测实验。实验中将温度补偿光纤光栅引入到该系统，并采用了多种软件滤波技术。在15km的光纤上实现了4个扰动点的同时检测和定位，达到了8m的空间分辨率，15dB的信噪比和2m的定位精度，是迄今为止国际已知报道中最多的扰动同时定位点数。最后提出了一种实用化多功能结构健康和边界安防光纤检测系统，并进行了初步的实验研究。 (5)提出了一种适用于多功能光纤分布式安防监测系统的新型数据处理和信号解调方案，在LabVIEW平台下开发了实现该解调方案的Φ-OTDR监测软件。
[Abstract]:Distributed optical fiber transmission technology is a kind of sensing technology which uses optical fiber as both transmission and sensing medium. It can be used for remote real-time monitoring of measurement parameters. The perimeter security system based on distributed optical fiber sensing is a new generation security system. Compared with the traditional electromechanical security system, it has the advantages of high sensitivity, small volume, light weight and strong resistance to electromagnetic radiation. General distributed optical fiber security systems, such as interferometric optical fiber sensing systems such as M-ZG Sagnac, can only achieve single point detection. In order to detect and locate multiple intrusion points simultaneously, a multi-function optical fiber security system based on phase sensitive optical time domain reflectometer (桅-OTDR) is developed in this paper. As a new security detection system, it not only has the ability to detect and locate multiple intrusion simultaneously, but also has the advantages of good concealment, accurate location, suitable for long distance and large range monitoring, and has a broad application prospect in the field of security protection. In this paper, the practical technology of multifunctional optical fiber security system based on 桅-OTDR is studied. The main work is as follows: (1) the research status of distributed optical fiber sensing technology based on OTDR and interferometer is described, and the differences between the two sensing technologies are compared. The unique advantages and development prospects of 桅-OTDR system based on OTDR and interference principle are analyzed. (2) the light scattering phenomenon in optical fiber is introduced, and the detection and positioning principle of 桅-OTDR system is analyzed. The theoretical analysis and simulation of the system are carried out in combination with the optical fiber backscattering discrete model and Monte Carlo method. (3) the effects of laser linewidth, cumulative average number, pulse width and intrusion signal on the performance of the system are studied. Firstly, it is found that the noise decreases first and then slowly with the increase of the cumulative average number, and the SNR increases first and then decreases with the increase of pulse width. Then, it is found that the signal to noise ratio (SNR) and location accuracy change periodically with the intrusion signal phase, and the influence of the intrusion signal frequency on the false report rate of the system is obtained. Finally, a preliminary solution to some defects in the system is proposed and an experimental study is carried out. (4) A set of multifunctional optical fiber security system is set up, and the parameters and selection requirements of each device in the system are studied, and the multi-point intrusion detection experiment is carried out. In the experiment, the temperature compensated fiber grating is introduced into the system, and a variety of software filtering techniques are used. At the same time, four disturbance points are detected and located on the fiber of 15km, which achieves spatial resolution of 8m, SNR of 15dB and location accuracy of 2m. It is the most known number of simultaneous location points of disturbance in the world. Finally, a practical multi-functional structure health and boundary security optical fiber detection system is proposed, and a preliminary experimental study is carried out. (5) A new data processing and signal demodulation scheme for multifunctional optical fiber distributed security monitoring system is proposed. A 桅-OTDR monitoring software is developed to realize the demodulation scheme on LabVIEW platform.
【学位授予单位】：东华大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN253

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