David Sean Farrell

US Patent:

6516063, Feb 4, 2003

Filed:

Mar 24, 2000

Appl. No.:

09/535305

Inventors:

David S. Farrell - Lisle IL
Tianfang Liu - De Kalb IL

Assignee:

Tellabs Operations, Inc. - Naperville IL

International Classification:

H04M 908

US Classification:

37940608, 37940601

Abstract:

A non-linear processor for use in an echo canceller is set forth. The non-linear processor includes a center clipping digital filter receiving an echo compensated signal. The non-linear processor provides a center clipped output signal having non-linear thresholds at values of +T and -T. The value of T is dynamically dependent, at least in part, on echo return loss measurements. To limit the processors susceptibility to corruption from double-talk conditions, the non-linear processor inhibits the dynamic setting of the T value when a double-talk condition is present. Additionally, or in the alternative, the non-linear processor locks the value of the echo return loss measurement after a predetermined number of consecutive echo return loss measurements have values falling within a predetermined range of one another. Such locking further reduces the susceptibility of the non-linear processor to corruption from double-talk conditions.

US Patent:

6614907, Sep 2, 2003

Filed:

Jan 18, 2000

Appl. No.:

09/484947

Inventors:

Kenneth P. Laberteaux - South Bend IN
Richard C. Younce - Wakarush IN
Bruce E. Dunne - Naperville IL
David S. Farrell - Lisle IL

Assignee:

Tellabs Operations, Inc. - Naperville IL

International Classification:

H04M 100

US Classification:

37940603, 37940608

Abstract:

An echo canceller circuit for use in an echo canceller system is set forth that provides sensitive double-talk detection. The echo canceller circuit comprises a second digital filter having adaptive tap coefficients to stimulate an echo response occurring during the call. The adaptive tap coefficients of the second digital filter are updated over the duration of the call using a Least Mean Squares process having an adaptive gain a. A channel condition detector is used to detect channel conditions during the call. The channel condition detector is responsive to detected channel conditions for changing the adaptive gain a during the call. For example, the channel condition detector may detect the presence of a double-talk condition and set the adaptive gain a to zero. Similarly, the channel condition detector may detect the occurrence of a high background noise condition and set the adaptive gain a to a level less than 1 that is dependent on the detected level of the background noise. Other similar channel conditions and corresponding adaptive gain settings may likewise be utilized.

US Patent:

7020278, Mar 28, 2006

Filed:

Oct 15, 2002

Appl. No.:

10/271189

Inventors:

David S. Farrell - Lisle IL, US
Tianfang Liu - De Kalb IL, US

Assignee:

Tellabs Operations, Inc. - Naperville IL

International Classification:

H04M 1/00

US Classification:

37940605, 37940601, 37940604, 37940608

Abstract:

A non-linear processor for use in an echo canceller is set forth. The non-linear processor includes a center clipping digital filter receiving an echo compensated signal. The non-linear processor provides a center clipped output signal having non-linear thresholds at values of +Tand −T. The value of Tis dynamically dependent, at least in part, on echo return loss measurements. To limit the processor's susceptibility to corruption from double-talk conditions, the non-linear processor inhibits the dynamic setting of the Tvalue when a double-talk condition is present. Additionally, or in the alternative, the non-linear processor locks the value of the echo return loss measurement after a predetermined number of consecutive echo return loss measurements have values falling within a predetermined range of one another. Such locking further reduces the susceptibility of the non-linear processor to corruption from double-talk conditions.

US Patent:

7200222, Apr 3, 2007

Filed:

Jun 23, 2003

Appl. No.:

10/602949

Inventors:

Kenneth P. Laberteaux - South Bend IN, US
Richard C. Younce - Wakarush IN, US
Bruce E. Dunne - Naperville IL, US
David S. Farrell - Lisle IL, US

Assignee:

Tellabs Operations, Inc. - Naperville IL

International Classification:

H04M 1/00

US Classification:

37940606, 37940609, 37940608, 37940605

Abstract:

An echo canceller circuit for use in an echo canceller system is set forth that provides sensitive double-talk detection. The echo canceller circuit comprises a second digital filter having adaptive tap coefficients to simulate an echo response occurring during the call. The adaptive tap coefficients of the second digital filter are updated over the duration of the call using a Least Mean Squares process having an adaptive gain a. A channel condition detector is used to detect channel conditions during the call. The channel condition detector is responsive to detected channel conditions for changing the adaptive gain a during the call. For example, the channel condition detector may detect the presence of a double-talk condition and set the adaptive gain a to zero. Similarly, the channel condition detector may detect the occurrence of a high background noise condition and set the adaptive gain a to a level less than 1 that is dependent on the detected level of the background noise. Other similar channel conditions and corresponding adaptive gain settings may likewise be utilized.

US Patent:

7450714, Nov 11, 2008

Filed:

Jan 19, 2006

Appl. No.:

11/336348

Inventors:

David S. Farrell - Lisle IL, US
Tianfang Liu - De Kalb IL, US

Assignee:

Tellabs Operations, Inc. - Naperville IL

International Classification:

H04M /08

US Classification:

37940605, 37940602

Abstract:

A non-linear processor for use in an echo canceller is set forth. The non-linear processor includes a center clipping digital filter receiving an echo compensated signal. The non-linear processor provides a center clipped output signal having non-linear thresholds at values of +Tand −T. The value of Tis dynamically dependent, at least in part, on echo return loss measurements. To limit the processor's susceptibility to corruption from double-talk conditions, the non-linear processor inhibits the dynamic setting of the Tvalue when a double-talk condition is present. Additionally, or in the alternative, the non-linear processor locks the value of the echo return loss measurement after a predetermined number of consecutive echo return loss measurements have values falling within a predetermined range of one another. Such locking further reduces the susceptibility of the non-linear processor to corruption from double-talk conditions.

US Patent:

20060115077, Jun 1, 2006

Filed:

Jan 10, 2006

Appl. No.:

11/329597

Inventors:

Kenneth Laberteaux - South Bend IN, US
Richard Younce - Wakarush IN, US
Bruce Dunne - Naperville IL, US
David Farrell - Lisle IL, US

International Classification:

H04M 9/08

US Classification:

379406010

Abstract:

An echo canceller circuit for use in an echo canceller system is set forth that provides sensitive double-talk detection. The echo canceller circuit comprises a second digital filter having adaptive tap coefficients to stimulate an echo response occurring during the call. The adaptive tap coefficients of the second digital filter are updated over the duration of the call using a Least Mean Squares process having an adaptive gain a. A channel condition detector is used to detect channel conditions during the call. The channel condition detector is responsive to detected channel conditions for changing the adaptive gain a during the call. For example, the channel condition detector may detect the presence of a double-talk condition and set the adaptive gain a to zero. Similarly, the channel condition detector may detect the occurrence of a high background noise condition and set the adaptive gain a to a level less than 1 that is dependent on the detected level of the background noise. Other similar channel conditions and corresponding adaptive gain settings may likewise be utilized.

US Patent:

60319089, Feb 29, 2000

Filed:

Nov 14, 1997

Appl. No.:

8/970874

Inventors:

Kenneth P. Laberteaux - South Bend IN
Richard C. Younce - Wakarush IN
Bruce E. Dunne - Naperville IL
David S. Farrell - Lisle IL

Assignee:

Tellabs Operations, Inc. - Lisle IL

International Classification:

H04M 100

US Classification:

379410

Abstract:

An echo canceller circuit for use in an echo canceller system is set forth that provides sensitive double-talk detection. The echo canceller circuit comprises a second digital filter having adaptive tap coefficients to simulate an echo response occurring during the call. The adaptive tap coefficients of the second digital filter are updated over the duration of the call using a Least Mean Squares process having an adaptive gain a. A channel condition detector is used to detect channel conditions during the call. The channel condition detector is responsive to detected channel conditions for changing the adaptive gain a during the call. For example, the channel condition detector may detect the presence of a double-talk condition and set the adaptive gain a to zero. Similarly, the channel condition detector may detect the occurrence of a high background noise condition and set the adaptive gain a to a level less than 1 that is dependent on the detected level of the background noise. Other similar channel conditions and corresponding adaptive gain settings may likewise be utilized.

US Patent:

61988197, Mar 6, 2001

Filed:

Nov 14, 1997

Appl. No.:

8/970639

Inventors:

David S. Farrell - Lisle IL
Tianfang Liu - De Kalb IL

Assignee:

Tellabs Operations, Inc. - Lisle IL

International Classification:

H04M 900

US Classification:

379410

Abstract:

A non-linear processor for use in an echo canceller is set forth. The non-linear processor includes a center clipping digital filter receiving an echo compensated signal. The non-linear processor provides a center clipped output signal having non-linear thresholds at values of +T. sub. NLP and -T. sub. NLP. The value of T. sub. NLP is dynamically dependent, at least in part, on echo return loss measurements. To limit the processor's susceptibility to corruption from double-talk conditions, the non-linear processor inhibits the dynamic setting of the T. sub. NLP value when a double-talk condition is present. Additionally, or in the alternative, the non-linear processor locks the value of the echo return loss measurement after a predetermined number of consecutive echo return loss measurements have values falling within a predetermined range of one another. Such locking further reduces the susceptibility of the non-linear processor to corruption from double-talk conditions.