The Key Technology And Its Design Of Perimeter Alarm System Based On Distributed Optical Fiber Sensings

With the development of the society and the progress of science,a large number of social wealth,heavily military and the important facilities are need security products for effective prevention to ensure their safety.Although,traditional security alarm system has achieve a certain security defense effect,but there are some technical defects.Optical fiber perimeter alarm system based on distributed optical fiber sensing can recognise timely,and has the function of long-distance monitoring,precise positioning,and low rate of false positives ect.Whitch can overcome the shortcoming of traditional perimeter security system.Therefore,it has extensive application prospect in the civil and military,and become a hot spot of research at home and abroad.In this paper,based on the study of distributed optical fiber sensing intrusion technology,the main research contents are as follows:First,this paper expounds the basic principle and composition of distributed optical fiber perimeter alarm system,puts forward the system of sensor type,working band,positioning accuracy and positioning relative error and other technical indicators.Studied tkey technologies of system,such as:the distributed optical fiber sensing technology,localization algorithm,pattern recognition technology,signal demodulation technology,system detection range.And clear mainly two key techniques of this topic research:pattern recognition technology and positioning algorithm.Secondly,distributed optical fiber sensing systems are analyzed with the method of time domain.Analyzed the invasion of external artificial interference,breeze and drizzle interference,small animals climb interference,cyclical weaker mechanical interference of typical response characteristics of these four types,and using Labview software simulation to verifying.Then,the paper discusses several distributed sensor positioning methods based on the interference principle.This paper studies the measuring principle of cross-correlation method to measuring time delay.Advanced the time delay estimation algorithm to make signal peak even more prominent,so that time lag will more accurate.Finally,according to the design index choosing ASE light source module,the G652 D sensing optical fiber,the LSM-PIN photodetector,the 2 x 2 fiber coupler,PCI8521 data acquisition card to complete the design of the system.Using Labview software to simulat the system under the condition of invasions in different position,the results meet the requirements of system design.The research and the design of optical fiber alert system has its theoretical innovation and guidance to engineering practice.