Baoli Wang

Author:

Baoli Wang

ISBN #:

3631465335

US Patent:

20020067824, Jun 6, 2002

Filed:

Dec 4, 2000

Appl. No.:

09/729005

Inventors:

Baoli Wang - Old Bridge NJ, US

International Classification:

H04M001/00
H04M009/00
H04M009/08

US Classification:

379/406060

Abstract:

A two-step training method for the estimation filter in the echo cancellation (EC) path of the analog front-end (AFE) circuit for a modem, such as an asymmetric digital subscriber line (ADSL) modem. During the first step, the transmit (TX) path is turned off and a digital TX signal (e.g., a pseudo white gaussian noise signal) is applied to the EC path essentially bypassing the EC estimation filter. During the second step, the EC path is turned off and a digital TX signal (e.g., the same pseudo white gaussian noise signal) is applied to the TX path. Coefficients for the EC estimation filter are then generated based on the digital RX signals recorded during the two training steps. In particular, the recorded digital RX signals are transformed to the frequency domain, where one is divided into the other. The resulting digital signal is then transformed back to the time domain, where it is used to generate the coefficients for the EC estimation filter. For Digital Multi-Tone (DMT) applications, the two-step training method of the present invention should be able to be implemented using at most four DMT symbols.