Signal denoising based on improved wavelet packet thresholding function

A new wavelet packet thresholding function is proposed for signal denoising in the wavelet domain. The new threshold function has the same characteristic of continuity with the soft-thresholding function, and also overcomes the defects. Wavelet packet transformation is a method for analysis of relations between time and frequency. It is much better than wavelet transformation in analyzing signals of medium and high frequencies and is applied to the signal denoising analysis. To remedy drawbacks identified in the traditional hard and soft threshold for signal denoising, an improved threshold quantization method be proposed, which applies new threshold function to achieve the continuity and differentiability. The application of this method not only removes the ring effect from the signal, but also keeps the signal details. The experimental results show that the performance of the proposed method is superior to that of conventional denoising approaches.