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:
Jun. 10, 1980
Filed:
Sep. 26, 1977
Michael M Meyer, Concord, CA (US);
Other;
Abstract
An alarm system in which local transmitters emit substantially pure acoustic signals for at least a predetermined minimum interval. The receiver includes a microphone and amplifier for transducing the acoustic signals into electrical signals. These electrical signals pass through two bandpass stages, the second being a phase locked loop circuit. An RC timing network is connected to the second bandpass circuit. After about 7500 cycles of the electrical signal have been received an 'alarm received' signal occurs. The 'alarm received' signal is applied to the triggering input of a free-running pulse generator which supplies pulse trains to a counter and is itself halted when the counter reaches a first intermediate state. A second 'alarm received' signal is required to restart the free-running pulse generator and thus advance the counter beyond said first intermediate state. Thereafter, when the counter reaches a second intermediate state, the occurrence of the corresponding second intermediate state signal actuates a suitable alarm signal to warn of intrusion or some other hazardous condition.