Dual mode tuner for co-existing digital and analog television signals
US6725463B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Aug 1, 1997 |
| Grant date | Apr 20, 2004 |
| Priority date | — |
| Expiry date | Aug 1, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N21/426
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A dual mode tuner/receiver is disclosed in which both analog and digital signals can be received and processed. A low pass filter allows all channels below a selected frequency enter the circuit. A precisely controlled dual conversion circuit creates an intermediate frequency (IF) signal. An automatic carrier detection circuit monitors the IF signal and determines whether the signal is of analog or digital format and intermediate frequency filters are adjusted based upon the type of signal detected. A coherent oscillator circuit generates in-phase and quadrature reference signals that are used by video and audio detectors for further processing of the IF signal. In-phase and quadrature outputs are provided for digital signals and composite video and audio outputs are provided for analog signals.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.