Security system with interference detection
US4737771A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 23, 1986 |
| Grant date | Apr 12, 1988 |
| Priority date | — |
| Expiry date | Jul 23, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B25/007
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A security system having one or more sending units for transmitting an electromagnetic signal representative of a condition such as fire, smoke, intrusion, battery condition, an emergency or other condition to a central receiving unit. Upon reception of an electromagnetic signal, the receiving unit provides an electromagnetic carrier detect signal to a microprocessor. A software timer within the microprocessor keeps track of the time over which the carrier is detected. If the carrier detection continues for a time longer than about 20 seconds, then a jamming indication signal is provided to one or more outputs. While the system is being jammed, alarms are ignored thus avoiding false alarms due to interference.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.