Method and echo canceller for echo cancellation with a number of cascade-connected adaptive filters
US5428605A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 13, 1994 |
| Grant date | Jun 27, 1995 |
| Priority date | — |
| Expiry date | May 13, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B3/23
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
Echo-cancellation with the aid of a number of cascade-connected adaptive filters, wherein each filter forms an output signal for cancelling its respective part of an echo signal appearing on a line included in a four-wire loop. The filters will preferably be able to converge rapidly, at least for relatively short impulse responses, and to provide effective echo-cancellation for different kinds of impulse response. Those filters which are required for the echo cancellation at that moment in time are ascertained by calculating a special quality measurement for each filter. There is formed an echo-reduced signal which is equal to the difference between the original, echo-included signal and the sum of the output signals from those filters that are needed for the echo-cancellation. These filters are updated with the echo-reduced signal, whereas the remainder of the filters are updated with signals formed as the difference between the echo-reduced signal and the output signal of respective filters.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.