Echo canceller for a long-distance telephone network
US4527020A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 22, 1981 |
| Grant date | Jul 2, 1985 |
| Priority date | — |
| Expiry date | Sep 22, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B3/23
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
An echo canceller for use in a long-distance telephone network having a four-wire circuit and a two-wire circuit in which echoes are inherently produced at the junction of the four-wire circuit and the two-wire circuit. A sample interpolator converts the incoming digital signal into a digital signal having the same sampling rate as that of the outgoing digital signal on the basis of relative positions of sampling time for corresponding imaginary envelopes of the incoming and outgoing digital signals. An echo estimator produces an estimated echo signal responsive to the output of the sample interpolator for cancelling the echo signal. The estimated echo signal is substracted from the unprocessed digital signal to produce an echo-cancelled digital signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.