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. 15, 1980
Filed:
Apr. 28, 1978
Masakatsu Watanabe, Tokyo, JP;
Hochiki Corporation, Tokyo, JP;
Abstract
In an alarm system utilizing a bidirectional wired television system, a large number of subscribers are located in a plurality of group units, whereby first specified frequencies which are common to respective of the group units but are different for the subscribers in each group unit are assigned to the respective subscribers in the respective group units to which are assigned another second specified frequencies which are different from one another, and still another third specified frequencies which are different for a plurality of types of alarms are assigned to the plurality of types of alarms. The group units are polled from a central station for each type of the plurality of alarms by means of interrogating signals comprising the signals of the second specified frequencies and the signals of the third specified frequencies, so that when an abnormal condition exists at any of the subscriber locations in the polled group units, the subscriber generates a signal of the first specified frequency assigned thereto to answer to the polling for that type of alarm corresponding to the abnormal condition. The central station discriminates and displays the answering subscriber and type the alarm condition in accordance with the frequency of the answer signal and the second and third specified frequencies generated for the polling at the time when the answer was made.