Research On The Detection Method Of Fence Invasion Based On Brillouin Optical Time Domain Analysis Technique

Based on Brillouin Optical Time Domain Analysis(BOTDA)technology,the sensor has the advantages of long detection distance,high measurement precision and strong anti-interference ability,The fence intrusion detection system in the perimeter security field has a broad application prospects,Therefore,based on BOTDA fence intrusion detection system research has important practical significance.In this thesis,through the review of domestic and foreign literature and the research of important places in the perimeter security fence intrusion detection technology in the status quo,combining the unique advantages of stimulated Brillouin scattering,and the method of detecting the center frequency of gravity is proposed creatively,The thesis designs a BOTDA fence intrusion detection system,and the system overcomes the shortcomings of the traditional BOTDA distributed fiber optic sensor measurement time-consuming,slow detection reaction,and the research on several kinds of fence invasion detection methods(to detect fiber strain as an example)conducted an in-depth study;finally,the reliability of the system is verified by the relevant experiments.The main contents of the thesis are as follows:1.In this thesis,the Brillouin scattering theory are briefly introduced,the sensing mechanism of the fiber are analyzed,the relationship between Brillouin frequency shift and Brillouin optical power and fiber strain are discussed,the theory for the system design of this paper basis are been found.2.The experimental data processing methods and software designed in the system are designed and built,the principle of mean filter to the sensor signal processing are introduced,the Brillouin frequency shift fitting and peak detection technology are briefly analyzed;the principle and application of Brillouin frequency shift detection method and center-of-gravity frequency detection method are introduced emphatically.the system performance indicators in the thesis is briefly analyzed,including system SNR,sensing accuracy and spatial resolution,the direction for the subsequent experimental research in the thesis is pointed out.The system performance indicators are briefly analyzed,the indicators including system SNR,sensing accuracy and spatial resolution,the direction for the subsequent experimental study is pointed out.3.The experimental platform based on BOTDA fence intrusion detection system is designed and built.a gain type of BOTDA system is built through using the spectral analyzer to obtain +1 order edge band light wave constitutes;then the RS232 serial communication interface is built to send instructions and acquisition interface initialization settings to get the original optical signal required for the experiment.the VC ++ in the MFC module are designed to achieve the experimental data acquisition and sensor signal display;then the corresponding test results of optical fiber strain detection were analyzed through using the Brillouin frequency shift detection method,the center of gravity frequency detection method and the original optical signal intensity detection method.4.The performance of the system is tested and analyzed,and the sensitivity of the system is obtained.The experimental results show that the system has a spatial resolution of 4m.A threshold method and a spectral analysis method are proposed to detect the fence intrusion.The simulation test of the spectrum analysis method and the analysis of the experimental results are given.Through the above research shows that,the system and the detection method designed in this thesis are feasible for fence intrusion monitoring.