Generating a stop signal of an automatic search procedure for a broadcasting station using an available AFC signal
US4941204A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 27, 1989 |
| Grant date | Jul 10, 1990 |
| Priority date | — |
| Expiry date | Jan 27, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03J7/28
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
During an automatic search scan of a broacasting station of a video receiver's tuner, the AFC signal generated by an existing automatic frequency control circuit of the receiver is applied to an input of four comparators. A first, switched threshold comparator commutes when the AFC signal is greater than the two switched threshold values EQU VA'<AFC>VA"; and enables a second comparator with a fixed threshold V1 comprised between the two switched threshold values of the first comparator. When the second comparator commutes causes the generation by an output buffer of a signal suitable for arresting the automatic search scan having thus detected on the AFC characteristic the presence of a carrier. When the automatic search scan is performed in an opposite direction, a similar detecting function is performed by means of a third, switched threshold, comparator commuting when the AFC signal is lower than the two switched threshold values: EQU VB'>AFC<VB"; and enables a fourth comparator, with a fixed threshold V2 which is comprised between the two switched threshold values of the third comparator, and which my commuting causes the generation, by the same output buffer, of the arresting …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.