Homodyne automatic frequency control circuit
US4006429A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 26, 1975 |
| Grant date | Feb 1, 1977 |
| Priority date | — |
| Expiry date | Sep 26, 1995 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03C3/09
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
Homodyne automatic frequency control circuitry maintains the mean or center output frequency of a controlled oscillator, e.g., the output of a voltage controlled oscillator effecting frequency modulation, equal to the output frequency of a reference oscillator. The composite AFC circuitry employs ganged sampling switches and a common mode error obviating common frequency detector (e.g., a discriminator) to alternately store voltages representative of the reference and controlled oscillator frequencies in capacitors connected to the inputs of a difference amplifier. The difference amplifier acts through an integrator to supply any necessary correction potential to the control port of the controlled oscillator when the signals stored in the two capacitors differ, signalling that the mean output frequency of the controlled oscillator has departed from that of the reference oscillator.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.