The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 21, 1982
Filed:
Nov. 20, 1980
Ronald W Mongeon, San Jose, CA (US);
Stellar Systems, Inc., San Jose, CA (US);
Abstract
An intrusion warning system for protecting a wall or fence, in particular a chain-link fence, against intrusion by cutting through and/or climbing over same. A small-diameter shielded electrical cable, e.g. a coaxial cable or a shielded twisted pair is mounted on the fence and the vibrations of the fence detected by sensing the small electrical field generated when the dielectric material between the conductors of the cable is stressed by the minute flexing of the cable caused by such vibrations. The sensed electric field signal is AM detected, shaped and then processed as to duration and persistence. An alarm indicating an attempted cut-through type of intrusion is activated if a preselected number of signals of very short duration, indicating abrupt disturbances of the fence, are detected. A separate alarm indicating an attempted climb-over intrusion is activated only if the detected signal persists for a period of time longer than that of the signals used for the cut-through indication and is present for a predetermined portion of a preset time period.