Echo canceling system for a bit pump and method of operating the same

• US 20060039550A1
• Filed: 08/05/2005
• Published: 02/23/2006
• Est. Priority Date: 08/29/2000
• Status: Abandoned Application

• Current Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Milisavljevic, Mile, Chadha, Mandeep Singh, McCaslin, Shawn Robert
• Application Number:
  US11/198,686
• Publication Number:
  US 20060039550A1
• Time in Patent Office: Days
• US Class Current: 379/406.90
• CPC Class Codes: H04B 3/23 using a replica of transmitted signal in the time domain, e.g. echo cancellers

Abstract

An echo canceling system, method of attenuating echo, and a bit pump and transceiver employing the system and method. The echo canceling system is couplable between a transmit and receive path of the bit pump and receives and attenuates the echo in a receive signal propagating along the receive path. In one embodiment, the echo canceling system includes a slave echo canceling stage that employs a filter coefficient to attenuate the echo. The echo canceling system also includes a separation circuit, coupled to the slave echo canceling stage, that generates data representing a residual echo substantially exclusive of the receive signal. The echo canceling system still further includes a master echo canceling stage, coupled to the separation circuit, that receives the data and modifies the filter coefficient based thereon.

Claims

1. An echo canceling system couplable between a transmit and receive path of a bit pump and adapted to receive and attenuate an echo in a receive signal propagating along said receive path, comprising:

a slave echo canceling stage configured to employ a filter coefficient to attenuate said echo;

a separation circuit, coupled to said slave echo canceling stage, configured to distinguish a residual echo from said receive signal and generate data representing said residual echo; and

a master echo canceling stage, coupled to said separation circuit, configured to receive said data and modify said filter coefficient based thereon.

2. The echo canceling system as recited in claim 1 wherein said master and slave echo canceling stages are configured to receive a transmit signal from said transmit path, said transmit signal being delayed to said master echo canceling stage.

3. The echo canceling system as recited in claim 1 wherein said separation circuit comprises an equalizer/slicer stage configured to determine a symbol associated with said receive signal.

4. The echo canceling system as recited in claim 3 wherein said separation circuit further comprises an estimator stage, coupled to said equalizer/slicer stage, configured to employ said symbol and develop an estimated receive signal.

5. The echo canceling system as recited in claim 4 wherein master echo canceling stage is configured to generated an echo canceling signal and said separation circuit is configured to generate said data representing said residual echo as a function of said estimated receive signal, said echo canceling signal and a delayed receive signal.

6. The echo canceling system as recited in claim 1 wherein said master and slave echo canceling stages each comprise finite impulse response filters and infinite impulse response filters.

7. The echo canceling system as recited in claim 1 wherein said master and slave echo canceling stages each comprise a DC canceller.

8. For use with a bit pump having a transmit and receive path, a method of attenuating an echo in a receive signal propagating along said receive path, comprising:

employing a filter coefficient to attenuate said echo;

distinguishing a residual echo from said receive signal;

generating data representing said residual echo; and

receiving said data and modifying said filter coefficient based thereon.

9. The method as recited in claim 8 further comprising receiving a transmit signal from said transmit path.

10. The method as recited in claim 8 wherein said generating comprises determining a symbol associated with said receive signal.

11. The method as recited in claim 10 wherein said generating further comprises employing said symbol to develop an estimated receive signal.

12. The method as recited in claim 11 further comprising generating an echo canceling signal and said generating said data representing said residual echo is a function of said estimated receive signal, said echo canceling signal and a delayed receive signal.

13. The method as recited in claim 8 further comprising generating said filter coefficient.

14. The method as recited in claim 8 wherein said modifying said filter coefficient is performed by finite impulse response filters and infinite impulse response filters.

15-28. -28. (canceled)