Linda L King

US Patent:

62630784, Jul 17, 2001

Filed:

Jan 7, 1999

Appl. No.:

9/226530

Inventors:

Hugh J. McLaughlin - Mountain View CA
Linda J. King - San Jose CA
Tamara L. Logan - Cupertino CA

Assignee:

SignalWorks, Inc. - Mountain View CA

International Classification:

H04B 323

US Classification:

379411

Abstract:

An echo canceller system and a method of filtering an outgoing signal utilize a volume compensator that operates in tandem with a primary adaptive filter to cancel echo due to a change in echo response of the system within a broadcasting environment. In particular, the volume compensator is designed to quickly adapt to a change in echo response due to an increase or decrease in the broadcast volume of a loudspeaker of the system. The echo canceller system may be incorporated into a personal computer system for a full-duplex speakerphone application. The volume compensator includes a supplementary adaptive filter that operates in parallel with the primary adaptive filter to cancel echo. The primary adaptive filter operates on the outgoing signal to cancel echo that may have been introduced into the outgoing signal along with speech of a near-end caller. The supplementary adaptive filter operates in parallel to but in conjunction with the primary adaptive filter to also cancel the echo in the original outgoing signal.

US Patent:

62691619, Jul 31, 2001

Filed:

May 20, 1999

Appl. No.:

9/315774

Inventors:

Hugh J. McLaughlin - Mountain View CA
Linda J. King - San Jose CA
Tamara L. Logan - Cupertino CA

Assignee:

SignalWorks, Inc. - Mountain View CA

International Classification:

H04M 100

US Classification:

379406

Abstract:

A full duplex speakerphone system and a method of detecting a valid near-end talker component within an outgoing signal utilize a near-talker estimator that produces a near-talker energy estimate using a spectrum analysis. The near-talker energy estimate is indicative of the amount of the valid near-end talker component within the outgoing signal. Depending on the near-talker energy estimate, the system may attenuate the outgoing signal and/or incoming signal and adjust the filter process executed by an adaptive filter of the system in order to provide a clear voice communication between connected parties. In the preferred embodiment, the near-talker estimator operates with at least one processing unit to sample the outgoing signal that has been filtered, or "cancelled," of echo by an acoustic echo canceller of the system. The energy of the echo-cancelled outgoing signal is compared to an echo energy envelope to determine whether a certain portion of the echo-cancelled outgoing signal can be attributed to a valid near-end talker. The echo energy envelope represents a potential echo return of the incoming signal in a worst case scenario that has been increased by several factors, such as an external gain, ERLE, and a preselected uncertainty factor.