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. 23, 1996
Filed:
Feb. 09, 1995
Yoichi Haneda, Tokyo, JP;
Shoji Makino, Tokyo, JP;
Masashi Tanaka, Tokorozawa, JP;
Yutaka Kaneda, Tokorozawa, JP;
Nippon Telegraph and Telephone Corporation, Tokyo, JP;
Abstract
In an echo cancelling method of a p-order fast projection algorithm which subtracts an estimated echo signal y(k) from a microphone output signal u(k) to obtain an error signal e(k), adaptively calculates a pre-filter coefficient .beta.(k) from the auto-correlation of a received speech signal x(k) and the error signal, generating an intermediate variable z(k) updated by a coefficient s(k) obtained by smoothing the pre-filter coefficient, convolutes the received speech signal x(k) and the intermediate variable z(k), calculates the inner product of the auto-correlation of the received speech signal and the smoothed pre-filter coefficient s(k) and adding the inner product and the convoluted output to obtain the estimated echo signal, the magnitudes of the received speech signal x(k) and the error signal e(k) are compared and when the result of comparison satisfies a predetermined condition, a reset signal is generated to set the pre-filter coefficient .beta.(k) to zero for at least a period of time p, thereby preventing the accuracy of estimated echo characteristics from lowering during double-talk or send single-talk.