Echo canceller having an adaptive filter with a dynamically...

Details Echo canceller having an adaptive filter with a dynamically... Echo canceller having an adaptive filter with a dynamically...

2005-09-27

2005-09-27

Ngo, Chuong D (Department: 2193)

Electrical computers: arithmetic processing and calculating

Electrical digital calculating computer

Particular function performed

C379S406010

Reexamination Certificate

active

06950842

ABSTRACT:
The present invention is directed to an echo canceller adapted for use in a communication system that includes a hybrid circuit. The echo canceller comprises an adaptive digital filter that generates an estimated echo signal {circumflex over (z)}[k] in response to: (i) a sampled input data sequence x[k] and (ii) an error signal sequence e[k] indicative of the difference between a near end signal sequence y[k] and the estimated echo signal {circumflex over (z)}[k]. The adaptive digital filter computes filter coefficients based upon the error signal sequence e[k] using a stochastic quadratic descent estimator, such as for example a least mean square (LMS) estimator, that employs a dynamically adjustable step size vectorμ[k]. The adaptive digital filter computes the dynamically adjustable step size vectorμ[k] of the formμ_⁡[k+1]=μ_⁡[k]+α⁢ ⁢ϕ_⁡[k]·x_⁡[k]⁢e⁡[k]⁢|μminμmax,whereφ[k+1]=φ[k]•(1−μ[k]•x2[k])+e[k])+e[k]x[k] and α is a scalar. In an open loop embodiment, the dynamically adjustable step size vectorμ[k] equals toμ[k]=μ[k]1, that is, all elements of the vector take the same value collapsing to the particular case of a scalar. The step size is computed using an expression of the form μ[k+1]=μ[k]+ξ[k], where ξ[k] is an empirically derived set of values.

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Simon Haykin,Adaptive Filter Theory, 3rdEdition, 1996, pp. 4-5.
Simon Haykin,Adaptive Filter Theory, 1986, pp. 1-43 and 195-219.

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