Method of initializing a filter in an echo canceller and communication system using said method
US4593161A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 22, 1984 |
| Grant date | Jun 3, 1986 |
| Priority date | — |
| Expiry date | Jun 22, 2004 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B3/238
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A method of initializing a filter in an echo canceller as used in a telephone system that includes hybrid transformers for connecting unidirectional lines to bidirectional lines and vice versa. Said method includes the steps of successively transmitting sequences of real and imaginary components of a signal exhibiting an uniform amplitude (i.e. flat) spectrum; receiving and storing sequences of echoes of each of said sequences of components; calculating the fast Fourier transform of complex sequences obtained from the stored sequences of echoes; rotating the terms of the Fourier transform; calculating the inverse transform of the sequence obtained by rotating said terms; and sorting the terms of the inverse transform to derive therefrom the values of the initial coefficients of said filter in said echo canceller.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.