Remote alarm system
US4531115A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 26, 1982 |
| Grant date | Jul 23, 1985 |
| Priority date | — |
| Expiry date | Jul 26, 2002 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B3/1083
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A remote alarm system provides a transmitter having an audio frequency signal generator circuit, a modulator circuit forming a current source modulated by the audio frequency signal and a radio frequency oscillator circuit modulated by the current source, and a receiver having a super-regenerative detector, an amplifier connected thereto, a notch filter for selectively filtering the audio frequency signal, an alternating current rectifier for rectifying the audio frequency signal, a delay circuit for delaying activation of an alarm signal until a signal from the rectifier circuit is present for a predetermined amount of time and for determining a period of time for activation of an alarm signal, and an alarm means for generating an alarm signal in response to the output of the delay circuit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.