System and method for eliminating offset echo in a data connection over a cellular cordless telephone service
US5953658A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 8, 1997 |
| Grant date | Sep 14, 1999 |
| Priority date | — |
| Expiry date | Jan 8, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B3/238
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A system and method is discloded for training echo cancelers during a training sequence of a data connection between a first modern connected to a cellular cordeless phone and a second modem, wherein the cellular cordless phone in operating a microcellular mode as opposed to a cellular mode. In such circumstances, where an intermittent two-wire channel interconnects the microcell base station and a central office associated with the public switched telephone network (PSTN), an offset echo will occur in the remote echo of the second modem and the local echo of the first modem. The offset echoes can be attributed to a radio frequency (RF) delay between the cellular cordless phone and the microcell base station. The first modem can make accommodations for the RF delay by increasing the delay time utilized in setting its near-end echo canceler. The second modem can be spoofed into setting its taps for its far-end echo canceler accuratly, despite the RF delay the first modem, by reducing its preset delay when responding to the ranging signal of the second modem. Thus, in accordance with the features of the invention, only the first modem need be configured to overcome offset echo.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.