Process and device for adaptive identification and adaptive echo

Details Process and device for adaptive identification and adaptive echo Process and device for adaptive identification and adaptive echo

1996-08-29

1998-03-31

Zele, Krista

Telephonic communications

Subscriber line or transmission line interface

Network interface device

379406, 379411, H04M 900

Patent

active

057347158

ABSTRACT:
To estimate the response of a system to an input signal, on the one hand the input signal and on the other hand an observation signal, a component of which is said response to the input signal, are received, an error signal is determined by subtracting from the observation signal the input signal filtered by an identification filter representative of the response of said system, and the coefficients of the identification filter are adapted by taking into account the input signal and the error signal. If the adaptation takes into account an adaption stepsize .mu..sub.t, the latter is varied according to: .mu..sub.t =a/(c+d. P2.sub.t /P1.sub.t), where a, c and d denote positive constants, P1.sub.t denotes an estimate of the power of the input signal and P2.sub.t denotes an estimate of the power of the observation signal or of a disturbance component of said observation signal. The variable .mu..sub.t can also be employed to adapt the gains of an echo canceller with adaptive gains.

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Patent Abstracts of Japan, vol. 17, No. 69 & JP-A-04 271622 (NEC Corp), Sep. 28, 1992.
H. Perez Meana et al., "A Time Varying Step Size Normalized LMS Echo Canceller Algorithm", Proc. of Eusipco-94, pp. II-249-II-252, Edimburg, Scotland, Sep. 1994.
Dirk T.M. Slock, "On the Convergence Behavior of the LMS and the Normalized LMS Algorithms", IEEE Trans. on Signal Processing, vol. 41, No. 9, pp. 2811-2825, Sep. 1993.
K. Ozeki et al., "An Adaptive Algorithm Using an Orthogonal Projection to an Affine Subspace and Its Properties", Electronics and Communications in Japan, vol. 67-A, No. 5, pp. 19-27, 1984.

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