Intrusion detector system
US4166273A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 19, 1977 |
| Grant date | Aug 28, 1979 |
| Priority date | — |
| Expiry date | Sep 19, 1997 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B25/008
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
An intrusion detector system for detecting the presence of moving targets in one or more surveillance zones and activated either by the presence of the moving target or directly by some positive action for transmitting an alarm signal causing the provision of a predetermined number of pulses having predetermined time periods. A tone generator and control circuitry receiving the timed pulses, generates a combination of multiple tones of discreetly different frequencies during the timed pulses, the combination of multiple tones of each timed pulse being of different frequencies than the combination of multiple tones of each other timed pulse, to provide a tone-coded message that is transmitted to a receiver. Control circuitry of the processor, in response to the initial reception of the tone-coded message, provides a predetermined number of pulses having predetermined time periods compatible with the pulses of a valid tone-coded message so as to have substantially coincident time frames in which appropriate multiple tones can be present, and is operative in response to a particular combination of multiple tones present in each time frame in sequence to provide an output alarm indicat…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.