Study On Key Technologies Of Leaky Coaxial Cable Perimeter Intrusion Detection System

The role of a perimeter intrusion detection system is that the system can intelligently and efficiently send out alarm information when human intrusion occurs in its defense region.The commonly used perimeter intrusion detection system mainly includes the pulse electronic fence,the active infrared,the vibration cable,the leaky coaxial cable and so on.In these perimeter intrusion detection system,only the leaky coaxial cable perimeter intrusion detection system can detect the intruder and locate the intruder's position at the same time.Moreover,it has good concealment and can be installed anywhere.Therefore,the leaky coaxial cable perimeter intrusion detection system has been become a hot spot research field for the perimeter intrusion detection system.In this paper,the design of the leaky coaxial cable perimeter intrusion detection system was mainly studied on the digital domain.Firstly,the structure of leaky coaxial cable and the characteristics of the signal transmission were analyzed.Then the leaky coaxial cable type of the system used was given.Based on the analysis of positioning technology and signal detection method,the structural model of the leaky coaxial cable perimeter intrusion detection system was proposed.Secondly,this paper put forward the phase encoding modulation technology to improve the system's anti-jamming,and introduced the design scheme of transmitting signal in detail.Through analyzing the properties of M sequence and the Barker code sequence,this paper presented a method of Golay code encoding.Combining with the characteristics of the leaky coaxial cable,the appropriate frequency carrier signal was selected.According to the positioning of the system,the algorithm of correlation accumulation ranging was proposed and the processing scheme of receiving signal was introduced in detail.Then the system was modeled and simulated by using Matlab to verify the transmitting and receiving scheme.After that the system's transmitting and receiving circuits were implement on the FPGA platform.Quartus II and Modelsim were utilized to verify the project's timing simulation and complete the layout of the schematic diagram.The transmitting system comprised a baseband coding module,a modulation module and a carrier module.The receiving system comprised a synchronization module,a digital down conversion module,a correlation processing module and a storage transmission module.Finally,the hardware platform of the leaky coaxial cable perimeter intrusion detection system was established.The test results show that the system can timely and accurately detect the human intruder and its positioning accuracy is up to 1 m when the two leaky coaxial cable distance is about 1.2 meters,while a bandwidth of 10.4MHz and the center frequency of 31.25 MHz signal is used as the transmitting signal.The system can work continuously and stably with a low false alarm rate and a low false negative rate.