Design Of Fiber Optic Sensing Perimeter Security System Based On FPGA

With the rapid development of social economy,the national infrastructure construction has been continuously improved.In order to ensure the safety of important places or areas and prevent illegal intruders from entering,a variety of precautions have been widely applied.Distributed optical fiber sensing technology integrates sensing and transmission.It has the advantages of large measurement range,long monitoring distance,high sensitivity,strong concealment,anti-electromagnetic interference,etc.It is widely used in health monitoring of large building,aerospace,perimeter security and other fields.The distributed optical fiber vibration sensor based on the principle of interference can sense and restore the external vibration signal in the optical fiber deployment range to meet the vibration detection needs of sensitive areas.With the continuous improvement of detection index of security system,further research is still needed in the realization of wider monitoring range,faster response speed and higher accuracy of vibration detection.To solve these problems,this paper designs an optic fiber sensing perimeter security system based on Field-Programmable Gate Array(FPGA).Based on the principle of Sagnac interference,a double zone vibration detection system is constructed by optic switch to improve the monitoring range.Using the advantage of FPGA architecture,the response performance of optical fiber perimeter security system is improved significantly,and the real-time intrusion detection is realized.The Improved Minimum Control Recursive Average Algorithm(IMCRA)is studied to improve the SNR and the accuracy of early warning.This paper studies from the following aspects:(1)The vibration detection mechanism of interferometric optical fiber is analyzed theoretically,and the related principle of the vibration information demodulation is expounded.The defense fiber perimeter security system based on Sagnac interference is built to promote the disturbance detection range,and the core device parameters of the system are introduced.(2)The scheme of vibration data acquisition and transmission based on FPGA is designed,the working principle and design flow of FPGA are introduced,the overall design framework of hardware circuit is described,the whole hardware circuit with FPGA as the core is built,and the specific scheme of data acquisition and transmission is described respectively.(3)The control software based on Microsoft Foundation Classes(MFC)is developed,which realized the operation control of the sensor system,designed the functions of data display and storage,constructed the graphical interactive interface,and optimized the fluency of the software operation through the design of multi-threaded row structure,so as to ensure the stable operation of the software for a long time.(4)On this basis,the main performance indicators of the zone-type distributed optical fiber vibration sensing prototype were tested,and the integrated design of the system was completed.Through experiments,the system intrusion vibration detection,frequency response and early warning accuracy were tested,combined with the IMCRA denoising algorithm,the system false alarm rate was reduced,and an engineering prototype was finally built.The research shows that the fiber optical sensing perimeter security system based on FPGA can detect the real-time disturbance in the dual defense area and realize the early warning of intrusion behavior,which provides a new design scheme for the field of perimeter intrusion detection and early warning of key sites.