Patent ID: 6967584
Filing Date: 2005-11-22
Classification: G08B

Abstract:
1. An intrusion detection system comprising: a coaxial cable having a first electrically conductive cable member, a second electrically conductive cable member, and an electrical insulating member disposed between the first conductive cable member and the second conductive cable member, the first cable member being loosely disposed in the coaxial cable and thus freely movable relative to the insulating member, to provide an impedance change in response to a disturbance, and the coaxial cable capable of producing a terminal voltage in response to the disturbance; and a processing unit, operatively coupled to the coaxial cable, for propagating an injected signal into the coaxial cable and receiving a reflected signal altered by the impedance change along the coaxial cable, and locating the disturbance based on a timing differential between the reflected signal relative and the injected signal, in an active state, and for generating a signal in response to the terminal voltage produced from the coaxial cable, in a passive state.