Traffic radar and apparatus therefor
US4020490A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 20, 1974 |
| Grant date | Apr 26, 1977 |
| Priority date | — |
| Expiry date | Nov 20, 1994 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S13/92
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Apparatus is provided for determining the frequency of unknown periodic input signals and primarily generally sinusoidal signals which may be accompanied by substantial noise. More particularly a unique traffic radar or doppler radar is provided employing such frequency measuring apparatus. The apparatus includes a phase locked loop in which a frequency multiplier effect is produced and in which a frequency 12 times the periodic input signal being subjected to measurement is employed for taking two independent samples of the input signal and providing a synthetic representation of that signal. The two samples are centered about quadrature time references and are preferably conterminous. This signal can be measured and utilized for speed measuring purposes and other purposes where the accurate measurement of a periodic signal accompanied by noise is desired. The system includes two sampling gates to control the frequency of a variable controlled oscillator in a manner which accurately matches the oscillator output to a harmonic of the input and selects portions thereof to eliminate harmonic ambiguities. Circuit means is also provided for signal verification and for improved long-ter…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.