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:
Dec. 05, 1995
Filed:
Feb. 01, 1994
Harbhajan S Virdee, Richardson, TX (US);
Tandy Corporation, Forth Worth, TX (US);
Abstract
The length (or the number of taps) of an adaptive finite impulse response (AFIR) filter is continuously modified to produce optimal echo cancellation. In accordance with one illustrative embodiment, this modification is performed by increasing or decreasing the number of delayed samples which are used to generate an echo estimate. More specifically, the number of samples used to generate the echo estimate is determined by selecting a trial number of samples and operating the filter for a sufficient length of time to allow the tap weights in the filter to stabilize. The tap weights are then examined to determine whether the taps at the end on the filter contribute at least a first threshold amount to the echo estimate. If not, the number of samples used in the filter is reduced and the process repeated. If the taps at the end of the filter contribute more than a second threshold amount, the number of samples is increased and the process is repeated.