AFC System for a synthesizer tuning system
US4208741A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 2, 1978 |
| Grant date | Jun 17, 1980 |
| Priority date | — |
| Expiry date | Nov 2, 1998 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L7/24
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A voltage-controllable reference oscillator for a synthesized receiver. In one mode of operation the reference oscillator is injection locked to a crystal-controlled oscillator so that the receiver's local oscillator frequency is a rational multiple of the crystal oscillator frequency. In another mode of operation the reference oscillator is isolated from the crystal-controlled oscillator and its operating frequency is determined by the voltage applied at its tuning control terminal. The control voltage is selectively provided by a manually variable fine tuning circuit or by an AFC circuit. An acquisition delay circuit develops a pulse when a channel is selected or when the source of tuning voltage is changed, thereby assuring that the reference oscillator is operating in the injection-locked mode until the synthesizer phase-locked loop has achieved acquisition.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.