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Author: search.filters.author.Takahashi, Nobuaki

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    Stabilized fast adaptive high-speed noise canceller with parallel block structure
    (2004-01-01)
    Benjangkaprasert, Chawalit
    ;
    Takahashi, Nobuaki
    ;
    Takebe, Tsuyoshi
    This paper proposes a new implementation of an adaptive noise canceller based upon a parallel block structure, which aims to raise the processing and convergence rates and to improve the steady-state performance. The procedure is as follows: First, an IIR bandpass filter with a variable center angular frequency using adaptive Q-factor control and two adaptive control signal generators are realized by the parallel block structure. Secondly, a new algorithm for adaptive Q-factor control with parallel block structure is proposed to improve the convergence characteristic. In addition, the steady-state performance of the filter is stabilized by using the variable step size parameter in adaptive control of the center frequency and the speed up of the convergence rate is achieved by adopting a normalized gradient algorithm for adaptive control. Finally, simulation results are given to demonstrate the convergence performance.
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    High speed adaptive noise canceller with parallel block structure using input for stability
    (1998-12-01)
    Benjangkaprasert, Chawalit
    ;
    Anantrasirichai, Noppin
    ;
    Janchitrapongvej, Kanok
    ;
    Takahashi, Nobuaki
    In this paper, a new adaptive algorithm of high speed adaptive noise canceller with parallel block structure is proposed. First, an IIR bandpass filter with a variable center angular frequency using adaptive Q-factor control is shown in which the bandpass filter and the adaptive control signal generator are composed of parallel block structures. Secondly, if we use a large step size parameter of the adaptive updating algorithm for fast processing, the large step size parameter may cause a large variation after convergence of the adaptive algorithm. In order to reduce the variation after convergence of the adaptive algorithm, we propose a new adaptive updating algorithm in which is used the input for stability. This method has essentially the same convergence performance as the previous algorithm. However the variation after convergence of the new adaptive updating algorithm is always smaller than the one of the previous algorithm. The new algorithm has a small increment in computational complexity. Finally, the simulation results are given to demonstrate the convergence performance.
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    Simplified fast stabilized adaptive noise canceller with parallel block structure
    (1997-12-01)
    Benjangkaprasert, Chawalit
    ;
    Janchitrapongvej, Kanok
    ;
    Saingaroon, Ornlarp
    ;
    Takahashi, Nobuaki
    In this paper, a new simplified adaptive algorithm with parallel block structure using an IIR bandpass filter to improve the processing and convergence rates of adaptive noise canceller are proposed. The procedure is as follows Firstly, an IIR bandpass filter with a variable center angular frequency using adaptive Q-factor control by the parallel block structure. Secondly, the output signals of filter and generators with parallel block structure are analyzed by the use of a new simplified adaptive algorithm. In order to reduce the computational complexity, two generators are realized by using parallel block structure. In addition, the characteristics after the convergence of filter is then stabilized, and the speed up of the convergence rate has been achieved by means of a variable step size parameter which is in inversely to Q-factor. Finally, the simulation results are given to demonstrate the convergence performance.
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    High-speed adaptive noise canceller with parallel block structure
    (1996-01-01)
    Maruyama, Kiyoyasu
    ;
    Benjangkaprasert, Chawalit
    ;
    Takahashi, Nobuaki
    ;
    Takebe, Tsuyoshi
    An adaptive algorithm for a single sinusoid detection using IIR bandpass filier with parallel block structure has been proposed by Nishimura et al. However, the algorithm has three problems: First, it has several input frequencies being impossible to converge. Secondly, the convergence rate can not be higher than that of the scalar structure. Finally, it has a large amount of computation. In this paper, a new algorithm is proposed to solve these problems. In addition, a new structure is proposed to reduce the amount of computation, in which the adaptive control signal generator is realized by the parallel block structure. Simulation results are given to illustrate the performance of the proposed algorithm.