TVRO receiver system with tracking filter for rejection of image frequencies
US5060297A · kind A · utility
Inventors
Key dates
| Filing date | Apr 4, 1988 |
| Grant date | Oct 22, 1991 |
| Priority date | — |
| Expiry date | Apr 4, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B1/18
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A TVRO receiver for the reception of frequency modulated satellite broadcast signals is provided with the capability of efficiently rejecting image frequencies generated as the received signals undergo intermediate frequency translation. A TVRO tuner, which includes a super-heterodyne circuit having a voltage-controlled oscillator (VCO), means for supplying a controlling tuning voltage to the VCO, and a mixer for combining incoming 1st IF signals with the output frequency of the VCO to reduce the frequency of the 1st IF signals to a selected 2nd IF frequency, is provided with a tracking filter which is adapted to pass only the incoming 1st IF signals and effectively reject any image frequencies generated at the received signal frequencies. The tracking filter comprises at least one low-pass filter section and has a cut-off frequency which is controlled by the same tuning voltage used to regulate the output frequency of the VCO in such a way that the filter rejects frequencies exceeding the VCO output frequency. The filter is designed so that image frequencies, which are generated during the intermediate frequency translation stage as the sum of a given VCO output frequency and the …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.