Automatic frequency control system
US4032858A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 3, 1976 |
| Grant date | Jun 28, 1977 |
| Priority date | — |
| Expiry date | Jun 3, 1996 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L7/04
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A controllable oscillator is maintained at a center frequency f.sub.o by the inventive system. The oscillator signal is directly coupled to one input of a diode detector via a first path, and is alternately coupled, at a clock signal rate, to the second detector input via second or third paths. The second path has a selected transfer characteristic such that when it passes the oscillator signal the diode detector output is at a null. The third path includes a resonator whereby the oscillator signal passed therethrough results in a null at the detector output only when the oscillator is tuned to f.sub.o. The diode detector output is then phase detected with the clock signal thus producing an output correction signal which, when integrated, is fed back to the oscillator for precise control thereof. Since the system correction is dependent solely on an AC signal, errors due to the DC characteristics of the components, e.g. the detector diodes, may be eliminated.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.