Asymmetric duplex modem utilizing narrow band echo cancellation
US5579305A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 9, 1994 |
| Grant date | Nov 26, 1996 |
| Priority date | — |
| Expiry date | Feb 9, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L5/143
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A full-duplex modem having improved transmission speeds over voice grade telephone circuits that extends the concepts of asymmetric transmission to include echo cancellation techniques. The preferred modem has a high speed forward channel and an overlapping low speed back channel and is capable of transmitting or receiving over either of the channels, depending on the relative data rates. A narrow band echo canceler substantially cancels all or part of reflected transmit signals. Because the echo cancellation technique employed is narrow band, there is a significant reduction in the complexity and computational requirements for the modem.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.