• Title/Summary/Keyword: filtered-X LMS

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Optimization of Cancellation Path Model in Filtered-X LMS for Narrow Band Noise Suppression

  • Kim, Hyoun-Suk;Park, Youngjin
    • Transactions on Control, Automation and Systems Engineering
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    • v.1 no.1
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    • pp.69-74
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    • 1999
  • Adaptive algorithms based on gradient adaptation have been extensively investigated and successfully joined with active noise/vibration control applications. The Filtered-X LMS algorithm became one of the basic feedforward algorithms in such applications, but is not fully understood yet. Effects of cancellation path model on the Filtered-X LMS algorithm have investigated and some useful properties related to stability were discovered. Most of the results stated that the error in the cancellation path model is undesirable to the Filtered X LMS. However, we started convergence analysis of Filtered-X LMS based on the assumption that erroneous model does not always degrade its performance. In this paper, we present a way of optimizing the cancellation path modern in order to enhance the convergence speed by introducing intentional phase error. Carefully designed intentional phase error enhances the convergence speed of the Filtered X LMS algorithm for pure tone noise suppression application without any performance loss at steady state.

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Implementation of Active Noise Canceller via Filtered-X LMS Algorithm (Filtered-X LMS 알고리즘을 사용한 적응 잡음 제거기의 구현)

  • Ahn, Doo-Soo;Kim, Jong-Boo;Lee, Tae-Pyo;Choi, Seung-Wook
    • Proceedings of the KIEE Conference
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    • 1996.07b
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    • pp.1066-1068
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    • 1996
  • This paper concerns about the active noise canceller via filtered-X LMS algorithm. There are various kinds of algorithms to implement a active noise canceller. Traditional LMS algorithms are not enough to implement a sharp noise cancellation characteristics. We simulates a filtered-X LMS algorithm and implements an algorithm to the TMS320C5x DSP processor and shows that result.

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Experimental Study on Bi-directional Filtered-x Least Mean Square Algorithm (양방향 Filtered-x 최소 평균 제곱 알고리듬에 대한 실험적인 연구)

  • Kwon, Oh Sang
    • Journal of Korea Society of Digital Industry and Information Management
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    • v.10 no.3
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    • pp.197-205
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    • 2014
  • In applications of adaptive noise control or active noise control, the presence of a transfer function in the secondary path following the adaptive controller and the error path, been shown to generally degrade the performance of the Least Mean Square (LMS) algorithm. Thus, the convergence rate is lowered, the residual power is increased, and the algorithm can become unstable. In general, in order to solve these problems, the filtered-x LMS (FX-LMS) type algorithms can be used. But these algorithms have slow convergence speed and weakness in the environment that the secondary path and error path are varied. Therefore, I present the new algorithm called the "Bi-directional Filtered-x (BFX) LMS" algorithm with nearly equal computation complexity. Through experimental study, the proposed BFX-LMS algorithm has better convergence speed and better performance than the conventional FX-LMS algorithm, especially when the secondary path or error path is varied and the impulsive disturbance is flow in.

Analysis of Bi-directional Filtered-x Least Mean Square Algorithm (양방향 Filtered-x 최소 평균 제곱 알고리듬에 대한 해석)

  • Kwon, Oh Sang
    • Journal of Korea Society of Digital Industry and Information Management
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    • v.10 no.4
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    • pp.133-142
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    • 2014
  • The least mean square(LMS) algorithm has been popular owing to its simplicity, stability, and availability to implement. But it inherently has a problem of slow convergence speed, and the presence of a transfer function in the secondary path following the adaptive controller and the error path has been shown to generally degrade the stability and the performance of the LMS algorithm in applications of acoustical noise control. In general, in order to solve these problems, the filtered-x LMS (FX-LMS) type algorithms can be used and the bi-directional Filtered-x LMS(BFXLMS) algorithm is very attractive among them, which increase the convergence speed and the performance of the controller with nearly equivalent computation complexity. In this paper, a mathematical analysis for the BFXLMS algorithm is presented. In terms of view points of time domain, frequency domain, and stochastic domain, the characteristics and stabilities of algorithm is accurately analyzed.

Effects of Error Path Delay on Stability of the Filtered-x/Constrained Filtered-x LMS Algorithm

  • Na, Hee-Seung
    • The Journal of the Acoustical Society of Korea
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    • v.17 no.3E
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    • pp.43-46
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    • 1998
  • Many of the active noise control system utilize a form of the least mean square(LMS) algorithm. This paper discusses the dependence of the convergence rate on the acoustic error path in the popular algorithm which is conventional "filtered-x LMS" and introduces new algorithm "constrained filtered-x LMS". The proposed method increase the convergence region regardless of the time-delay in the acoustic error path. In the algorithms, coefficients of the controller are adapted using the residuals of constrained structure which are defined in such a way that the control process become stationary. Advantages of constrained filtered-x LMS algorithm is illustrated by convergence analysis in the mean sense.

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OPTIMIZATION OF ERROR PATH MODEL IN FILTERED-X LMS ALGORITHM FOR NAROW BAND NOISE SUPPRESSION

  • Kim, Hyoun-Suk;Park, Youngjin
    • 제어로봇시스템학회:학술대회논문집
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    • 1995.10a
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    • pp.43-46
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    • 1995
  • Adaptive algorithms based on gradient adaptation have been extensively investigated and successfully jointed with active noise/vibration control applications. The Filtered-X LMS algorithm became one of the basic feedforward algorithms in such applications, but still is not fully understood. The error path model effect on the Filtered-X LMS algorithm has been under the investigation and some useful properties related stability has been discovered. We are interested in utilizing the fact that the model error caused by the way optimizing the error path model in a view point of convergence speed of Filtered-X LMS algorithm for pure tone noise suppression application without any performance loss at steady state.

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Active Noise Control using Constrained Filtered-x LMS Algorithm (제한 Filtered-x LMS 알고리즘을 이용한 능동 소음제어)

  • 나희승;박영진
    • Journal of KSNVE
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    • v.8 no.3
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    • pp.485-493
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    • 1998
  • Many of the adaptive noise control systems utilize a form of the least mean square (LMS) algorithms. In the active control of noise, it is common practice to locate an error microphone far from the control source to avoid the near-field effects by evanescent waves. Such a distance between the control source and the error microphone makes a certain level of time-delay inevitable and, hence, may yield undesirable effects on the convergence properties of control algorithms such as filtered-x LMS. This paper discusses the dependence of the convergence rate on the acoustic error path in these popularalgorithms and introduces new algorithms which increase the convergence region regardless of the time-delay in the acoustic error path. Performances of the new LMS algorithms are presented in comparison with those by the conventional algorithms based on computer simulations and experiments.

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A Study on the Co-LMS Algorithm Characteristics of Real-time Applicants for Road Environment Calming (도로환경 정온화의 실시간 적용을 위한 Co-LMS 알고리즘의 특성 고찰)

  • Moon, Hak-Ryong;Shon, Jin-Geun
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.63 no.3
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    • pp.157-162
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    • 2014
  • The active noise control(ANC) method for noise problems solution generally uses filtered-X LMS algorithms. However, Filtered-X LMS algorithms were mainly used but these had a limitation that had to measure a transfer function of secondary noise path. However, newly proposed correlation-LMS algorithms have slightly much calculation and are minutely behind performance, these have a advantage not in measuring transfer function onerously so that we can easily adapt these in real time. Thus Co-LMS algorithm was developed to improve the real-time implementation performance under the variable input noise such as road noise environment. In this paper, the performance of the Co-LMS is presented in comparison with that of the Filtered-X LMS algorithm. Simulation results show that active noise control using Co-LMS have slightly much calculation and are minutely behind performance, these have a advantage not in measuring transfer function onerously so that we can easily adapt these in real time.

Characteristics of Filtered-X LMS Algorith for Two Tone Noise (두 정현파 소음에 대한 Filtered-X LMS 알고리즘의 특성연구)

  • 김현석;박영진
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1994.04a
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    • pp.16-21
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    • 1994
  • For the systems such as ANC(Active Noise Control) systems having auxiliary path after FIR type adaptive filter, Filtered-X LMS algorithm is effective. However behaviors of this algorithm has not been fully understood. The convergence property of this algorithm depends on not only cross correlation matrix between the filtered signals through model and real auxiliary path state solution of weight vector in Filtered-X LMS algorithm is investigated for under-determined case, over-determined case, and nonsingular case. Also, the convergence speed in case of two tone noise is investigated based on the eigenvalue spread of cross correlation matrix.

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Convergence of the Filtered-x LMS Algorithm for Canceling Multiple Sinusoidal Acoustic Noise (복수정현파 소음제거를 위한 Filtered-x LMS 알고리듬의 수렴 특성에 관한 연구)

  • Lee, Kang-Seung;Lee, jae-Chon;Youn, Dae-Hee;Kang, Young-Suk
    • The Journal of the Acoustical Society of Korea
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    • v.14 no.2
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    • pp.40-49
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    • 1995
  • Application of the filtered-x LMS adaptive filter to active noise cancellation requires to estimate the transfer charactersitics between the output and the error signal of the adaptive canceler. In this paper, we derive the filtered-x adaptive noise cancellation algorithm and analyze its convergence behavior when the acoustic noise consists of multiple sinusoids. The results of the convergence analysis of the filtered-x LMS algorithm indicate that the effects of the parameter estimation inaccuracy on the convergence behavior of the algorithm are characterized by two distinct components : Phase estimation error and estimated gain. In particular, the convergence is shown to strongly affected by the accuracy of the phase response estimate. Simulation results are presented to support the theoretical convergence analysis.

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