Filtered transmit cancellation in a full-duplex modem data access arrangement (DAA)
US6751202B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Apr 30, 1999 |
| Grant date | Jun 15, 2004 |
| Priority date | — |
| Expiry date | Apr 30, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B3/23
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
An improved data access arrangement device for use in full-duplex two-wire communication systems having a transmission impedance characteristic. The DAA includes a transmit amplifier and a receive amplifier adapted for connection to a two-wire line, a codec connected to the transmit amplifier for generating a transmit signal, a summation device connected to the receive amplifier, an echo cancellation path including a variable gain amplifier, where the path extends between the codec and the summation device, and wherein the variable gain amplifier is adjusted in accordance with the transmission impedance characteristic. The variable gain amplifier may include a gain register that is programmed by a microprocessor, or may have the gain set by user-configurable switches. The summation device is preferably an operational amplifier.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.