Emergency alert system
US5029290A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 2, 1990 |
| Grant date | Jul 2, 1991 |
| Priority date | — |
| Expiry date | Feb 2, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M11/04
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
An alarm system suitable for use in a telecommunications network in which a central switching system is capable of selectively providing a signal of a predetermined polarity to a plurality of remotely located stations without being dependent upon or impeding the ability of the central switching system to process relatively high volume communications traffic. Each of the remote stations is connected to the telecommunications network by an electrical conduction path. The stations are substantially unresponsive to the predetermined polarity signal. In response to an alarm indication signal, the system effects a reversal in the polarity of the signal provided to a selected subset of the remote stations. Each station in the selected subset responds to the polarity reversal by indicating an alarm condition.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.