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基于卷積型小波包變換的信號(hào)降噪研究
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    摘要:

    提出了一種基于卷積型小波包變換的多尺度降噪方法,。采用卷積型小波包變換,,克服了傳統(tǒng)小波包變換數(shù)據(jù)點(diǎn)數(shù)隨分解尺度的增加而呈指數(shù)減小的問(wèn)題,;改進(jìn)了噪聲方差估計(jì)方法,,較好地保留了信號(hào)的主要細(xì)節(jié),;采用了新的閾值函數(shù),,其表達(dá)式簡(jiǎn)單易于計(jì)算,,同Donoho軟閾值函數(shù)具有相同的連續(xù)性,,且克服了軟閾值函數(shù)中估計(jì)小波系數(shù)與分解小波系數(shù)之間存在著恒定偏差的問(wèn)題。仿真結(jié)果表明,,新的降噪方法有效抑制了在信號(hào)奇異點(diǎn)附近產(chǎn)生的Pseudo-Gibbs現(xiàn)象,,在降噪精度上優(yōu)于傳統(tǒng)的小波包降噪方法。

    Abstract:

    A multi-scale de-noising algorithm based on the convolution type of wavelet packet transformation was presented. This algorithm overcame shortcomings of the classical wavelet packet transformation, in which the length of sequences obtained always decreased by decomposition scales. The new algorithm improved estimated method of white noise standard deviation at each scale and thus kept the main edges of signal well. A new threshold function has been employed in this algorithm, which was simple in expression and as continuous as the Donoho's soft threshold function, and overcame the shortcoming of an invariable dispersion between the estimated wavelet coefficients and the decomposed wavelet coefficients of the soft-threshold method. Simulation results indicated that the new de-noising method suppressed the Pseudo-Gibbs phenomena near the singularities of the signal effectively and achieved better SNR gains than de-noising method based on classical wavelet packet transformation. 

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朱啟兵,李志華,陳立平.基于卷積型小波包變換的信號(hào)降噪研究[J].農(nóng)業(yè)機(jī)械學(xué)報(bào),2007,38(12):160-164.[J]. Transactions of the Chinese Society for Agricultural Machinery,2007,38(12):160-164.

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