Channel selection system for an electronic tuner
US4438528A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 3, 1982 |
| Grant date | Mar 20, 1984 |
| Priority date | — |
| Expiry date | Aug 3, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03J7/065
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
In a channel selection system using a PPL frequency synthesizing method in which the local oscillation frequency of a tuner is frequency-divided and compared with the frequency and the phase of a reference oscillator thereby to control the tuning voltage of a tuner, a channel selection system disclosed by this invention comprises a controller, a variable frequency divider the frequency division ratio of which is controlled by the above controller, an AFC circuit connected to this tuner, a first comparator having a first threshold voltage for detecting an H level of the inverted S character output of the AFC circuit, a second comparator having a second threshold voltage for detecting an L level of the inverted S character output, and a delay circuit connected to the output of at least one of the first and second comparators and delaying the rising edge of the comparison output.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.