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. 26, 1989
Filed:
Aug. 03, 1988
Applicant:
Inventor:
Steven G Goldstein, Los Angeles, CA (US);
Assignee:
Rabbit Systems, Inc., Santa Monica, CA (US);
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G08B / ;
U.S. Cl.
CPC ...
367 94 ; 200 6162 ; 307116 ; 307141 ; 340566 ;
Abstract
A detector and alarm is provided for monitoring air pressure variations in a monitored space, which variations correspond to an intrusion. An infra-sonic detector includes a microphone or the like and a low pass filter to retain only low frequency infra-sonic signals. The instantaneous infra-sonic signals are compared against a variable reference signal, which is a voltage lagging or delayed variant of the instantaneous signals. In this manner the detector is self adjusting for slow variations in the instantaneous signals but responds immediately to rapid variations to trigger an alarm.