Acoustic Echo Canceller System Materialized with a 16-bit Fixed Point Processing Type DSP

Jun'ichi SAKAGUCHI  Tsutomu HOSHINO  Kensaku FUJII  Juro OHGA  

Publication
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E82-A   No.12   pp.2818-2821
Publication Date: 1999/12/25
Online ISSN: 
DOI: 
Print ISSN: 0916-8508
Type of Manuscript: LETTER
Category: Acoustics
Keyword: 
acoustic echo canceller,  INLMS algorithm,  quantized-x algorithm,  block length adjustment,  fixed point processing,  

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Summary: 
This paper introduces an acoustic echo canceller system materialized with a 16-bit fixed point processing type DSP (Analog Devices, ADSP-2181). This experimental system uses the tri-quantized-x individually normalized least mean square (INLMS) algorithm little degrading the convergence property under the fixed point processing. The experimental system also applies a small step gain to the algorithm to prevent the double-talk from increasing the estimation error. Such a small step gain naturally reduces the convergence speed. The experimental system compensates the reduction by applying the block length adjustment technique to the algorithm. This technique enables to ceaselessly update the coefficients of the adaptive filter even when the reference signal power is low. The experimental system thus keeps the echo return loss enhancement (ERLE) high against the double-talk.