Research On Intrusion Location And Feature Recognition Of A Fiber Optic Security System

The current fiber optic security system in technology has made great progress,but there are still some problems.For example,positioning accuracy of optical fiber security system cannot meet the requirements of certain departments,cannot accurately analyze the characteristics of the incident,resulting in a very high false alarm rate.Aiming at the shortcomings of the current optical fiber perimeter security system,in order to improve the positioning accuracy of the system,reduce the misjudgment rate of intrusion characteristics,we designed a kind of area perimeter optical fiber security system,whice were based on the technology of separating the intrusion location and the source of the intrusion feature signal.Replacing the original plan that intrusion location signal and the feature identification signal mixed together in the acquisition scheme.This kind of scheme which used the time digital conversion technology(TDC)to locate the location of the invasion replaced the currently common scheme which used phase difference of demodulating the interference signal to locate.The current time digital conversion technology can achieve the measurement of ultra-short time difference,the resolution can reach to the rate of picosecond.It is very proper for optical positioning in the fiber to accurately locate and continuously measure distance.This research adopted the database query comparison technology based on the intrusion signal.Because the security system fiber signal interference signal contains a lot of intrusion information,this information will help people to distinguish the type of intrusion events and reduce misjudgment rate.In our stduy,an intrusion location program was designed which used intrusion time difference obtained by TDC as the time acquisition unit,and adopted DSP2812 chip as the core of the control board.The structure and program designs of the TDC and DSP communication module,DSP and the host computer to RS232 communication module were completed.Lab VIEW was used as the intrusion signal characteristic database signal storage and signal feature comparison.Through the construction of the experimental platform,Joint experimental debugging was completed based on intrusion locating of TDC and upper computer monitoring.The experimental results verified the positional accuracy,and achieved the expected design goal.LabVIEW-based monitoring interface could alarm with showing the intrusion location and time information.By simulated intrusion signal,system based on Lab VIEW and database matching query could achieve the feature quantity recognition.The simulation results confirmed the design feasible.