Browse Prior Art Database

Intruder Detection

IP.com Disclosure Number: IPCOM000090567D
Original Publication Date: 1969-May-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Gaston, CA: AUTHOR

Abstract

In detection systems such as burglar alarm systems, it is often desirable to know not only that an intruder or intruding object is present, but the location or approximate location of such intruder or intruding object. The system of drawing A detects not only the presence of an intruder, but the location as well. Thus, the values of the resistors are chosen in such a manner that, depending upon whether there is a break in the foil strip such as that upon a window or at a door switch or a trip wire, resistance values other than those for the system in normal operation are sensed by the sensing electronics.

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Intruder Detection

In detection systems such as burglar alarm systems, it is often desirable to know not only that an intruder or intruding object is present, but the location or approximate location of such intruder or intruding object. The system of drawing A detects not only the presence of an intruder, but the location as well. Thus, the values of the resistors are chosen in such a manner that, depending upon whether there is a break in the foil strip such as that upon a window or at a door switch or a trip wire, resistance values other than those for the system in normal operation are sensed by the sensing electronics. Depending upon the value of the resistors and the number of elements in the system, the sensing electronics can be programmed to instantly detect not only the presence of an intruder by change in resistance but the location as well, since each particular resistance corresponds to a particular break in the system. The table indicates some of the variations permitted within this system.

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The detection system of B can be operated by use of window foil strips or trigger mechanisms. This system, however, uses uniquely tuned resonant circuits. These are periodically stimulated by master control to ascertain that they still respond to the proper frequency. Each circuit contains a resonant loop which oscillates if its own distinctive frequency is impressed upon it by coupling to the capacitance C from the AC line. However, any interfere...