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:
Nov. 29, 1977
Filed:
Feb. 09, 1976
Charles S Ashworth, Jr, Warren, MI (US);
Audio Alert, Inc., Farmington Hills, MI (US);
Abstract
A security alarm with audio monitoring capability including a remote location to be protected, a central monitoring station and transmission lines coupled therebetween. The remote location includes a circuit for generating a DC transmission signal of a first normal polarity. Sensors are provided for detecting various alarm conditions and a switching apparatus responsive to the detection of an alarm condition by the sensors reverses the polarity of the DC signal to indicate the existence of an alarm condition. A plurality of microphones each having its own amplifier and sensitivity control are strategicaly placed about the remote location to pick up audio sounds originating therein. The AC audio signals from the microphones are superimposed onto the DC transmission signal and transmitted to the central monitoring station. The central monitoring station includes a first circuit isolated from the transmission lines by a first photo-optical coupler which monitors for open circuit or short circuit line faults; a second circuit isolated from the transmission lines by a second photo-optical coupler which monitors for a polarity reversal and generates an alarm signal indicative thereof; and a third circuit is isolated from the transmission lines by a transformer and which receives the superimposed AC audio signals. The third circuit renders all signals above a predetermined level audible to the operator at the central station. Additionally, the remote location may include a closed security loop having a plurality of serially connected normally-closed switches through the doors and windows which trigger a polarity reversal if the integrity of the loop is broken; a circuit for testing loop integrity; a signal injector for generating different and distinct audio tones for each different type of alarm condition possible and for superimposing the generated audio tones onto the DC transmission signal; and photo-optical line supervision circuitry. Furthermore, either or both of the remote location and the central station may be provided with manually operable coding keys for sending coded signals over the transmission lines.