Apparatus for and method of doppler motion detection with standing wave drift compensation
US4580249A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 26, 1984 |
| Grant date | Apr 1, 1986 |
| Priority date | — |
| Expiry date | Nov 26, 2004 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B13/1627
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Drift of the standing wave pattern in an acoustic doppler intrusion detection system with radiating and receiving transducers in a confined space is compensated by changing the operating frequency of the carrier wave generator when the magnitude of the received carrier wave is less than a predetermined threshold level. The magnitude of the received carrier wave is continuously monitored and compared to the threshold level. The generator frequency is incrementally increased until the carrier wave magnitude is optimum. This invention comprehends the apparatus for and method of optimizing signal strength at the receiving transducer by this technique.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.