Equalization and decision-directed loops with trellis demodulation in high definition TV
US6775334B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 3, 1999 |
| Grant date | Aug 10, 2004 |
| Priority date | — |
| Expiry date | Nov 3, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N11/24
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Improved decision feedback equalizer and decision directed timing recovery systems and methods suitable for use in connection with a dual mode QAM/VSB receiver system are disclosed. A trellis decoder operates in conjunction with a decision feedback equalizer circuit on trellis coded 8-VSB modulated signals. The trellis decoder includes a 4-state traceback memory circuit outputting a maximum likelihood decision as well as a number of intermediate decisions based upon the maximum likelihood sequence path. Any number of decisions, along the sequence, may be provided as an input signal to timing recovery system loops, with the particular decision along the sequence chosen on the basis of its delay through the trellis decoder. Variable delay circuitry is coupled to the other input of the timing recovery system loops in order to ensure that both input signals bear the same timestamp. Final decisions are output from the trellis decoder to a DFE in order to enhance the DFE's ability to operate in low SNR environments. A decision sequence estimation error signal is also generated and used to drive the tap updates of both the DFE and an FFE portion of the equalizer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.