Apparatus and method for reducing the risk of undesirable parameter drift of an adaptive filter used for echo cancellation
US5428681A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 7, 1994 |
| Grant date | Jun 27, 1995 |
| Priority date | — |
| Expiry date | Jul 7, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B3/23
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
Apparatus for reducing the risk of undesirable drifting of the parameters, so-called bursting, of an adaptive echo filter which is coupled between a receiving branch and a transmitting branch included in a four-wire loop. A difference signal (E) which contains no echo from the receiving branch is generated in the transmitting branch in a known manner. The apparatus includes an adaptive predictor filter which is coupled between the transmitting branch and the receiving branch and which functions to generate a compensation signal from the difference signal (E) when transmitting narrowband signals from a near-end. The compensating signal is subtracted from a signal which appears in the receiving branch and the predictor filter is updated in a manner to minimize the correlation between the difference signal (E) and the input signal (X') of the echo filter. A relatively small predictor filter is sufficient to essentially eliminate this correlation when transmitting signals which, at maximum, consist of some few single sinusoidal tones.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.