Hardware Design Of Perimeter Security Monitoring System Based On POTDR-distributed Optical Fiber Sensor

With the continuous development of culture and economy,the perimeter security of long distance has attracted more and more attention.Polarization-sensitive optical time domain reflectometry(POTDR)is one of the most sensitive technologies in the distributed optical fiber sensing(DOFS)technologies.With the characters of high resolution,high temperature resistance,electromagnetic interference immunity and other unique advantages,the POTDR has become one of the main methods to perimeter security monitoring system used in civil engineering,oil pipelines monitoring,high voltage engineering and other areas.As the current POTDR-based distributed optical fiber sensing systems are composed of the industrial personal computer(IPC)and data acquisition cards(DAR),the POTDR system is excluded from many practical applications for its complex system structure and high cost.In the paper,an embedded system for the long distance perimeter security monitoring application based on POTDR distributed optical fiber sensing system is designed,which is consist of FPGA&DSP architecture.The hardware of the embedded system is realized,and the processes of sensor signal acquisition and system control are designed.Then a test platform is set up to verify the system.Although the system hardware is realized in a single circuit board,it has completed the same functions as those of the traditional POTDR system composed of IPCs and DARs,so the structure is simplified and the cost is reduced in the system.It is suitable to be used in mass practional applications of the relative fields.The main work of the paper is as follows.(1)The overall scheme and the hardware circuit of the system are completed.The overall system scheme has been designed based on the features of POTDR distributed optical fiber sensor which can detect the abnormal disturbance and the intrusion information along the optical fiber.The functions of system control and data acquisition are realized on the basis of FPGA and DSP.The EP4CE6F17C8 and TMS320F28335 chip are respectively selected as the core of the data acquisition and system control.FPGA minimum system circuit,DSP minimum system circuit,communication circuit,power supply circuit and other schematic circuit diagram of the hardware circuit are designed.Then,the Printed Circuit Board(PCB)design has been completed on the basis of the schematic circuit diagram.(2)Based on the hardware circuit,the software of FPGA and DSP are designed.Bsides,the function of the hardware circuit is verified through the tests.Firstly,in order to realize the functions of FPGA control AD chip acquisition sensor signal and cache signal data,this procedure need to edit verilog code in the Quartus? software and make simulation analysis in the Model Sim software.Secondly,it has to write program in the CCS development environment to achieve the DSP functions of entire hardware circuit control and wavelet transform algorithm.Finally,we set up the test platform and environmenttest to verify the function of the hardware circuit in three scenarios: no interference,climbing and disturbance.The test results show that the abnormal disturbance and invasion along the optical fiber can be reliably detected using the system designed in the paper.