• Title/Summary/Keyword: Variable Time Step Size

Search Result 57, Processing Time 0.022 seconds

An algebraic step size least mean fourth algorithm for acoustic communication channel estimation (음향 통신 채널 추정기를 이용한 대수학적 스텝크기 least mean fourth 알고리즘)

  • Lim, Jun-Seok
    • The Journal of the Acoustical Society of Korea
    • /
    • v.35 no.1
    • /
    • pp.55-62
    • /
    • 2016
  • The least-mean fourth (LMF) algorithm is well known for its fast convergence and low steady-state error especially in non-Gaussian noise environments. Recently, there has been increasing interest in the least mean square (LMS) algorithms with variable step size. It is because the variable step-size LMS algorithms have shown to outperform the conventional fixed step-size LMS in the various situations. In this paper, a variable step-size LMF algorithm is proposed, which adopts an algebraic optimal step size as a variable step size. It is expected that the proposed algorithm also outperforms the conventional fixed step-size LMF. The superiority of the proposed algorithm is confirmed by the simulations in the time invariant and time variant channels.

Stability and accuracy for the trapezoidal rule of the Newmark time integration method with variable time step sizes (가변시간간격을 갖는 Newmark 시간적분법의 사다리꼴법칙에 대한 안정성과 정확도)

  • Noh, Yong-Su;Chung, Jin-Tae;Bae, Dae-Seong
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.21 no.10
    • /
    • pp.1712-1717
    • /
    • 1997
  • Stability and accuracy for the trapezoidal rule of the Newmark time integration method are analyzed when variable time step sizes are adopted. A new analytic approach to stability and accuracy analysis is also proposed for time integration methods with variable time step sizes. The trapezoidal rule with variable time step sizes has the "actual" unconditional stability which is the same as that of the method with constant time step sizes. However, the method with variable time step sizes is first-order accurate while the method with constant time step sizes is second-order accurate. accurate.

A Study on Variable Step Size LMS Algorithm using estimated correlation (추정상관값을 이용한 가변 스텝사이즈 LMS 알고리듬에 관한 연구)

  • 권순용;오신범;이채욱
    • Proceedings of the IEEK Conference
    • /
    • 2000.11d
    • /
    • pp.115-118
    • /
    • 2000
  • We present a new variable step size LMS algorithm using the correlation between reference input and error signal of adaptive filter. The proposed algorithm updates each weight of filter by different step size at same sample time. We applied this algorithm to adaptive multip]e-notch filter. Simulation results are presented to compare the performance of the proposed algorithm with the usual LMS algorithm and another variable step algorithm.

  • PDF

Modified Asymmetrical Variable Step Size Incremental Conductance Maximum Power Point Tracking Method for Photovoltaic Systems

  • Tian, Yong;Xia, Bizhong;Xu, Zhihui;Sun, Wei
    • Journal of Power Electronics
    • /
    • v.14 no.1
    • /
    • pp.156-164
    • /
    • 2014
  • The power-voltage (P-V) characteristic of a photovoltaic (PV) array is nonlinear and time varying with the change in atmospheric conditions. As a result, the maximum power point tracking (MPPT) technique must be applied in PV systems to maximize the generated energy. The incremental conductance (INC) algorithm, one of the MPPT strategies, is widely used for its high tracking accuracy, good adaptability to rapidly changing atmospheric conditions, and easy implementation. This paper presents a modified asymmetrical variable step size INC MPPT method that is based on the asymmetrical feature of the P-V curve. Compared with conventional fixed or variable step size method, the proposed method can effectively improve tracking accuracy and speed. The theoretical foundation and design principle of the proposed approach are validated by the simulation and experimental results.

I/Q Gain and Phase Imbalances Compensation Algorithm by using Variable Step-size Adaptive Loops at Direct Conversion Receiver (가변 스텝 적응적 루프를 이용한 직접 변환 방식 수신기에서의 이득 및 위상 불일치 보상 알고리즘)

  • 송윤정;나성웅
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
    • /
    • v.14 no.10
    • /
    • pp.1104-1111
    • /
    • 2003
  • The paper presents an algorithm for the compensation of gain and phase imbalances to exist between I-phase and Q-phase signal at direct conversion receiver. We propose a gain and phase imbalances blind equalization compensation algorithm by using variable step-size adaptive loop at direct conversion receiver. The blind equalization schemes have trade-off between convergence speed and jitter effect for the compensation of gain and phase imbalance. We propose the variable step-size adaptive loop method, which varies the loop coefficients according to errors, for recovering these problem. By using variable step-size adaptive loops, we propose to speed up the convergence process and reduce the jitter effect and simulation results show that the algorithm compensates signal loss and speeds up convergence time.

A New LMS Algorithm for Improved Convergence Time in Active Noise Control (수렴속도 개선을 위한 새로운 LMS 알고리즘)

  • Park, Kyoung-Ho;Kim, Il-Hwan
    • Journal of Institute of Control, Robotics and Systems
    • /
    • v.7 no.3
    • /
    • pp.276-279
    • /
    • 2001
  • Many industrial processes that are operated by rotating machines and large air-moving fans are excellent examples to which the single channel ANC systems can be applied. In these environments, the active noise control techniques are most popular nowadays. In this paper, a modified LMS algorithm(EAC, Error Amplitude Compared) is proposed. The algorithm is a kind of variable step-size LMS-type algorithm. Computer simulations show that the proposed EAC algorithm achieves a better convergence time than a conventional VS(Variable Step-Size) algorithm, Also, this algorithm has been implemented by using and experimental duct system.

  • PDF

CNC Tool Path Planning for Free-Form Sculptured Surface with a New Tool Path Interval Algorithm (새로운 공구경로간격 알고리듬을 이용한 자유곡면에서의 CNC 공구경로 계획)

  • Lee, Sung-Gun;Yang, Seung-Han
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.18 no.6
    • /
    • pp.43-49
    • /
    • 2001
  • A reduced machining time and increased accuracy for the sculptured surface are very important when producing complicated parts. The step-size and tool-path interval are essential components in high speed and high resolution machining. If they are small, the machining time will increase, whereas if they are large, rough surfaces will be caused. In particular, the machining time, which is key in high speed machining, is affected by the tool-path interval more than the step-size. The conventional method for calculating the tool=path interval is to select a small parametric increment of a small increment based on the curvature of the surface. However, this approach also has limitations. The first is that the tool-path interval can not be calculated precisely. The second is that a separate tool-path interval needs to be calculated in each of the three cases. The third is that the conversion from Cartesian domain to parametric domain or vice versa must be necessary. Accordingly, the current study proposes a new tool-path interval algorithm that do not involve a curvature and that is not necessary for any conversion and a variable step-size algorithm for NURBS.

  • PDF

An time-varying acoustic channel estimation using least squares algorithm with an average gradient vector based a self-adjusted step size and variable forgetting factor (기울기 평균 벡터를 사용한 가변 스텝 최소 자승 알고리즘과 시변 망각 인자를 사용한 시변 음향 채널 추정)

  • Lim, Jun-Seok
    • The Journal of the Acoustical Society of Korea
    • /
    • v.38 no.3
    • /
    • pp.283-289
    • /
    • 2019
  • RLS (Recursive-least-squares) algorithm is known to have good convergence and excellent error level after convergence. However, there is a disadvantage that numerical instability is included in the algorithm due to inverse matrix calculation. In this paper, we propose an algorithm with no matrix inversion to avoid the instability aforementioned. The proposed algorithm still keeps the same convergence performance. In the proposed algorithm, we adopt an averaged gradient-based step size as a self-adjusted step size. In addition, a variable forgetting factor is introduced to provide superior performance for time-varying channel estimation. Through simulations, we compare performance with conventional RLS and show its equivalency. It also shows the merit of the variable forgetting factor in time-varying channels.

Research about Adjusted Step Size NLMS Algorithm Using SNR (신호 대 잡음비를 이용한 Adjusted Step Size NLMS알고리즘에 관한 연구)

  • Lee, Jae-Kyun;Park, Jae-Hoon;Lee, Chae-Wook
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.33 no.4C
    • /
    • pp.305-311
    • /
    • 2008
  • In this paper, we proposed an algorithm for adaptive noise cancellation (ANC) using the variable step size normalized least mean square (VSSNLMS) in real-time automobile environment. As a basic algorithm for ANC, the LMS algorithm has been used for its simplicity. However, the LMS algorithm has problems of both convergence speed and estimation accuracy in real-time environment. In order to solve these problems, the VSSLMS algorithm for ANC is considered in nonstationary environment. By computer simulation using real-time data acquisition system(USB 6009), VSSNLMS algorithm turns out to be more effective than the LMS algorithm in both convergence speed and estimation accuracy.

An Efficient Time-Domain Electromagnetic Solution Using the Time-Domain Variable Resolution Concept (가변 시간 분해능 시간 영역 전자파 해석법)

  • Kim Hyung-Hoon;Park Jong-Il;Kim Hyeong-Dong
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
    • /
    • v.17 no.9 s.112
    • /
    • pp.890-894
    • /
    • 2006
  • To make the best use of known characteristics of the alternating-direction-implicit finite-difference time-domain (ADI-FDTD) method such as unconditional stability and modeling accuracy, an efficient time domain solution with variable time-step size is proposed. Numerical experiment shows that a time-step size for a given mesh size can be increased preserving a desired numerical accuracy over frequencies of interest. The proposed method can be used to analyze electromagnetic problems with reduced computation time.