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:
Feb. 16, 1999
Filed:
Mar. 31, 1997
Gerard Richter, Saint Jeannet, FR;
International Business Machines Corporation, Armonk, NY (US);
Abstract
A process for computing the coefficients C(i) of an adaptive filter (206) used in an echo-cancellation structure for a telecommunication apparatus. The process is based on the Least Mean Squared (L.M.S.) or gradient algorithm for computing the coefficients of the filter in accordance with the formula: ##EQU1## where e(i) is the estimation error and .alpha. is the step size used for performing an adjustement of the convergence of the filtering process. The process uses two different estimations of the power of the analog signal, a former short-term estimation and a latter long-term estimation in order to derive the appropriate value of the stepsize .alpha. which is used for computing the new coefficients. In the preferred embodiment the value of .alpha. is determined by dividing a constant .alpha..sub.0 being slightly lower than the maximum value ensuring stability of the convergence process by the greater of the two different estimations of the power of the analog signals.