Channel selection apparatus having automatic frequency compensation for transmission frequency error
US4817195A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 23, 1987 |
| Grant date | Mar 28, 1989 |
| Priority date | — |
| Expiry date | Dec 23, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03J7/065
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A channel selection apparatus having a double superhet tuner section (15) for converting one of a plurality of television channels contained in an input signal to a fixedly predetermined channel, includes an AFC circuit (11) for producing a frequency control voltage to execute closed-loop frequency control of the second local oscillator (5) of the tuner section while an AFC switch (16) is set in a first condition, whereas when the AFC switch is set in a second condition, a fixed frequency control voltage is applied to the second local oscillator and the frequency control voltage is applied to adjust the oscillation frequency of the first local oscillator (2) of the tuner section such as to compensate for any offset in the transmission frequency of a currently selected channel.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.