System and method for avoiding false convergence in the presence of tones in a time-domain echo cancellation process
US5592548A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 31, 1995 |
| Grant date | Jan 7, 1997 |
| Priority date | — |
| Expiry date | May 31, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B3/23
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A system and method for detecting convergence in an echo canceller prevent false convergence from occurring as a result of receiving only tones in an input signal. An adaptive filter is used in an echo canceller to estimate an echo signal produced by an unknown echo channel. The estimated echo signal is subtracted from the return signal to remove the echo produced by the unknown echo channel. To prevent the echo canceller from falsely converging on a signal which contains only tones a system and method are provided for detecting the presence of tones in the absence of other frequencies. Filter taps of the adaptive filter are filtered to produce a filtered signal. The amount of energy in the filtered signal is compared to the amount of energy in the unfiltered filter taps to determine whether only tones have been present. If only tones have been present, the echo canceller is not allowed to reduce the adaptation step size of the adaptive filter.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.