科研之友
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摘要
We propose an adaptive notch filter that realizes the phase shift of the all-pass filter by the expression of Fourier sine series. The method of controlling the weights of the all-pass filter formed by IIR filters is well known. However, these adaptive notch filters have not been put to practical use due to the peculiar stability problems of IIR filters and the problem of determining the degree of the IIR filter. The proposed adaptive notch filter is always stable since the all-pass filter is formed by exponential filters. Furthermore, the adaptive algorithm is a simple gradient-based algorithm and convergence of weights is guaranteed. The degree of the all-pass filter depends only on the required steepness of the elimination characteristic and does not depend on the number of narrowband signals that are to be eliminated. Furthermore, the proposed method is suitable for practical use because the elimination characteristic is hardly influenced by a broadband signal added to the narrowband signal. The analytical results and a rigorous verification of the above features by computer simulation are presented.
- 出版日期2010-5
