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:
Apr. 03, 1979
Filed:
Aug. 22, 1977
Applicant:
Inventors:
Dennis K Siemer, Mankato, MN (US);
Swen E Farland, Mankato, MN (US);
Assignee:
Other;
Primary Examiner:
Int. Cl.
CPC ...
G08B / ;
U.S. Cl.
CPC ...
340531 ; 340288 ; 3403 / ; 340538 ; 340539 ; 325 30 ;
Abstract
An alarm system for transmitting an alarm signal between remote locations utilizing frequency shift keying over conventional power lines. The alarm system includes a transmitter having a nominal frequency and circuitry for modulating the transmitter frequency. Upon detection of an alarm condition the modulating circuitry is disabled. A receiver is provided and has circuitry for detecting the presence or absence of modulation of the transmitter frequency. The receiver generates an alarm signal upon detection of absence of modulation and power failure of the system. The alarm signal is time-delayed to prevent nuisance alarms.