TVRO earth station receiver for reducing interference and improving picture quality
US4761825A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 30, 1985 |
| Grant date | Aug 2, 1988 |
| Priority date | — |
| Expiry date | Oct 30, 2005 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03J7/065
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A method of reducing terrestrial interference is provided for a TVRO earth station receiver comprising a super-heterodyne circuit including a voltage-controlled oscillator (VCO), a mixer for combining incoming first IF signals with the output of the VCO to reduce the frequency of the first IF signals to a second IF range having a predetermined nominal center frequency, a pass band filter for filtering the second IF signals and having a pass band centered on the nominal second IF center frequency, and a microprocessor for controlling the input voltage to the VCO and for automatically setting the controlling input voltage at prescribed levels in response to a "channel select" command signal, so that the VCO produces an output frequency which centers the received signal for a selected channel on the nominal second IF center frequency. The method includes offsetting the controlling input voltage from the prescribed level for a selected channel to offset the actual second IF center frequency relative to the center of the pass band of the filter, in a direction that removes at least a portion of the terrestrial interference from the pass band.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.