Reduced complexity equalizer for multi mode signaling
US6426972B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 19, 1998 |
| Grant date | Jul 30, 2002 |
| Priority date | — |
| Expiry date | Jun 19, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2025/03732
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A transmission channel equalizer system may be used to process either signals that have been modulated according to quadrature amplitude modulation (QAM) or vestigial sideband modulation (VSB) to convey digital symbols. The equalizer system includes a sparse digital filter having coefficients which are adaptively updated. The filter system includes a finite impulse response (FIR) filter which processes modulated pass-band RF signals and an infinite impulse response (IIR) filter which processes demodulated base-band signals. At least one of the FIR and IIR filters is implemented as a sparse filter. The filter system is responsive to a control signal to switch between processing QAM and VSB signals. The update algorithm for the equalizer employs a constant modulus algorithm (CMA) to acquire the digital signal and a decision directed (DD) algorithm to track the digital signal. The CMA algorithm used when VSB signals are processed is a single axis CMA (SACMA) algorithm. The filter converts the VSB signal into a pseudo QAM signal before the slicing operation which recovers the symbols from the converted VSB signal. The slicer identifies an encoded VSB symbol by partial trellis decoding …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.