关键词: 小波包变换, 改进希尔伯特—黄变换（HHT）, 分段插值, 混合插值, 特征提取

Abstract: As a new theory for adaptive time-frequency analysis，the Hilbert-Huang Transform（HHT） is considered to be experiential method，it’s necessary to be consummated.When curve fitting for envelope or mean with cubic spline interpolation，it’s easily to come into contact with overshoot and undershoot problems.To solve the disfigurement，the subsection interpolation arithmetic based on B spline curve and mixed interpolation curve arithmetic are proposed.Furthermore，it’s the effective technique to avoid the aliasing phenomena.An effective analysis method for non-stationary signal based on improved HHT and the Wavelet Packets Decomposition（WPD） is presented in this paper.The proposed method can not only solve the shortcoming in HHT，but also decrease the unnecessary noise influence，and improves the veracity of the signal feature extraction.The results of experiment indicate the proposed method is effective in feature extraction.

Key words: wavelet packet transform, improved Hilbert-Huang Transform, subsection interpolation, mixed interpolation, feature extraction