System for transmitting alarm information over telephone lines
US4262283A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 1, 1978 |
| Grant date | Apr 14, 1981 |
| Priority date | — |
| Expiry date | Mar 1, 1998 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B26/006
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
An alarm system for transmitting alarm information via telephone lines has a plurality of alarm transmitters which are located at subscribers' premises and are adapted to transmit signals indicative of the state of alarms associated with the transmitters along telephone lines to associated receivers. The receivers are located at one or more local exchanges and the receivers at a local exchange are all connected to a local processor. The or each local processor is connected to a central processor which can direct alarm information to one of a number of terminal stations. The local processors continuously scan the outputs of the receivers. When a local processor detects a signal indicative of an alarm condition it transmits a signal coded with the subscriber identity and destination for the alarm information to the central processor which routes the alarm message to the appropriate terminal station. Each transmitter produces a carrier wave which is modulated with one or more other frequencies according to the state of the alarm being monitored.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.