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:
Jul. 27, 2004
Filed:
Feb. 05, 2001
Youhong Lu, Vernon Hills, IL (US);
3Com Corporation, Santa Clara, CA (US);
Abstract
Methods and systems for echo cancellation are provided. According to one method, when a far end signal with an echo having a major body and a pure delay portion is received, a filter having a finite length is provided. Once the finite length filter covers a portion of an echo path, the method includes determining whether at least a portion of the echo major body is within the filter. In one embodiment, the filter is divided into a plurality of sub-windows, and the step of determining whether the filter covers the major body of the echo path includes using filter coefficients of the first sub-window. According to one embodiment, the major body of the echo path is detected by comparing a maximum value coefficient in the first sub-window with a predetermined threshold value. If the maximum value coefficient is greater than the threshold value, the major body is detected. If the major body is not detected in the first sub-window, the filter is shifted towards the major body portion of the echo path, and the step of determining whether the filter covers the echo major body is repeated.