Frequency domain processing of Doppler signals in a traffic monitoring system
US5912822A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 15, 1996 |
| Grant date | Jun 15, 1999 |
| Priority date | — |
| Expiry date | Oct 15, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S13/92
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Frequency domain processing is used to determine rapidly whether false signals are present, and to improve the accuracy of speed measurements by rejecting speed measurements that could be inaccurate due to the presence of false signals. A Doppler signal responsive to speed of a moving vehicle is generated by a Doppler radar transceiver. A digital computer transforms the Doppler signal into a frequency domain signal such as an energy spectrum, and the speed of the moving vehicle is computed from the weighted arithmetic mean of the energy spectrum. The mean value, however, is rejected as an indication of speed if the variance of the energy spectrum from the mean exceeds a threshold, or if a differential of the spectrum with respect to frequency exceeds a threshold. The frequency domain processing of the present invention can also be used to reject certain bands of frequencies in the Doppler signal, such as bands of frequencies that differ from the mean value by more than a threshold, and the mean value can then be recomputed to provide an even better indication of the speed of the moving vehicle. Moreover, speed samples computed from successive frames of spectrum can be averaged, and…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.