The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 26, 2000
Filed:
Dec. 13, 1995
Ying Wu, Grass Valley, CA (US);
3Com Corporation, Rolling Meadows, IL (US);
Abstract
An Acoustic Echo Control (AEC) device operates to reduce acoustic echo feedback in a speakerphone. An adaptive echo canceller responds to a far-end speech signal to generate an estimated echo which is subtracted from a near-end speech signal, to generate a compensated near-end speech signal. An Echo Return Loss (ERL) estimator provides an accurate but gradually adjusted estimate of the ERL of the echo canceller. A non-linear processor responds to the ERL estimation and provides additional attenuation to maintain the overall system ERL. The AEC device also incorporates dual talking mode detectors, one for the adaptive filter and one for the non-linear processor, to detect a plurality of talking modes, which are used to control the adaptation of the adaptive filter and the attenuation provided by the non-linear processor. A convergence indicator responds to the sudden echo path changes, and quickly corrects the ERL estimation; thereby adjusting the talking mode detector and the non-linear processor accordingly to maintain the overall system ERL and stability.