Apparatus and method for adapting a filter of an analog modem
US6600780B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 22, 1999 |
| Grant date | Jul 29, 2003 |
| Priority date | — |
| Expiry date | Jun 22, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2025/0377
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
Analog modems are enabled to better learn the slicing levels employed at the interface to a digital transmission network by reducing the effects of the various noise sources. Initially a training sequence is received to preliminarily adjust the analog modem's equalizer. Thereafter, a special training sequence, protected against intersymbol interference, is employed to collect samples of each slicing level, to ascertain the least mean squared value of each slicing level from the received samples and to obtain the channel's impulse response at each slicing level. Depending on the means squared error (MSE) between the input and the output of the slicer, the slicer tables continue to be updated, and the feed-forward and feed-backward equalizer filters are selectively adjusted in accordance with the channel impulse response ascertained at each of the slicing levels.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.