Fault detection in combination intrusion detection systems
US4833450A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 15, 1988 |
| Grant date | May 23, 1989 |
| Priority date | — |
| Expiry date | Apr 15, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B29/02
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
An intrusion detection system employs a microwave subsystem and a passive infra-red subsystem. Both systems must produce an output signal indicative of an intrusion in order for the system to produce an alarm. There is disclosed a supervision circuit which monitors the number of trips of the microwave system as well as the number of trips of the PIR system. If the number of trips which are indicative of false alarms exceeds preset counts then an alarm is produced indicating that there is a failure in the microwave or the PIR system. The system further monitors the microwave system to determine whether the transmit and receiving diodes are functioning properly. The system will also indicate a fault if an intruder or an object is placed within a predetermined protection dome implemented by the system. Hence the system can produce multiple faults indicative of subsystem failures to notify the user of the system that such a failure has occurred.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.