Rapid acquisition, tracking PLL with fast and slow sweep speeds
US4613825A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 20, 1984 |
| Grant date | Sep 23, 1986 |
| Priority date | — |
| Expiry date | Dec 20, 2004 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S331/02
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A tracking phase locked loop circuit in which the frequency of an oscillator portion thereof is varied over a range of frequencies in search of an incoming carrier is disclosed. The varying frequency occurs at two different sweep rates. A faster rate is used until the frequency of the phase locked loop's oscillator nears the frequency of the incoming carrier, and a slower rate is used until the circuit locks onto the carrier. A filter couples between mixer and sweep control circuit portions of the phase locked loop to provide information concerning the difference between oscillator frequency and incoming carrier frequency. The sweep control circuit distinguishes between the carrier and noise and switches rates accordingly.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.