Buried cable perimeter intrusion

Abstract

Perimeter intrusion detection system is an important and integral part of most physical security systems. Target detection sensors have attracted attention as rising terrorism incidents. In recent years, various target detection systems have been studied as a security system for important facilities to prevent terrorist attacks. For this purpose, many security systems with camera system have been mainly developed and used in the past. The security systems with leaky coaxial cable have been also proposed and developed in recent years. The project pertains detection, localization and identification of different objects using a pair of leaky coaxial cables along a prescribed route. In this system, two cables are installed parallel to each other with separation sufficient enough (1m to 3m) so as to cause the two cables to be loosely coupled. A RF transmitter is connected to one of the cables to supply RF signal at 800MHz for propagation there along. A matched RF receiver is attached to one end of second cable. A chirp frequency modulation provides a continuous target response having a baseband frequency that is proportional to the distance along the length of the cable. After location determination, the amplitude of the response is compared to a location specific threshold to determine if an intruder is present. The presence of a target (anybody which reflects or absorbs radio frequency energy) alters the magnitude and phase of the signal received at the other cable and, hence, provides a change in the return signal to the receiver connected to the receiving cable. This change in signal is processed digitally to discriminate between legitimate targets and changes due to undesirable targets such as animals. Point of intrusion is also located along a prescribed route.