Digital signal seeking tuning system
US3931579A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 1, 1974 |
| Grant date | Jan 6, 1976 |
| Priority date | — |
| Expiry date | Apr 1, 1994 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03J7/28
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A signal recognizing television tuning system employing a varactor tuner and a channel number computer for supplying derived channel numbers and intrachannel fractions, based upon the local oscillator frequency, to a comparator which controls a ramp voltage source for the varactor tuner. A digital counter supplies a selected channel number to the comparator and the ramp voltage is changed until (1) equality exists between both derived and selected channel numbers and (2) the intrachannel fraction is within predetermined limits such that the system is tuned to receive only signals falling within a restricted frequency range. If no signal is recognized, the counter supplies a next adjacent channel number to the comparator. Signal recognition means stop further operation of the counter upon recognition of a signal within the restricted frequency range.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.