Direct Pole/Zero Estimation for Adaptive Echo Cancellation

• Main Authors: Jou, Jau Jeng, 周昭政
• Other Authors: S. F. Hsieh
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/06757695918764883217

碩士 === 國立交通大學 === 電信工程研究所 === 86 === The problem of long filter length in adaptive FIR filters not onlyslows down the convergent speed but also increases the hardware cost.Adaptive IIR filters seem appropriate because they can provide infinitelylong response to approximatethe room impulse responses. But two disadvantages limitthe adaptive IIR filter to be widely used. One is the filter stability andthe other is local optimum in the error surface.Based on recursive prediction error algorithmwe will develop the state-based direct pole/zero (SBDPZ) estimation method.Unlike the traditional coefficients estimation method, SBDPZ canmonitor the poles' locations directly without finding the rootsof the denonimator polynomial.However, matrix operation is a serious computation load, so we deriveda simplified gradient method to reduce the computation complexity.Nonminimum phase system will also be investigated by further computationof the error gradient stage by stage.Finally, we use the combined method of the conventional NLMS and direct poleestimation to predict the zeros and poles, respectively, for acoustic echo cancellation.Therefore, we can not only keep the easier stability checkproperty but also reduce the computation complexity.