基于EMD与小波阈值的爆破震动信号去噪方法
A method for blasting vibration signal denoising based on empircal mode decomposition and wavelet threshold

针对小波阈值法去噪效果有限和EMD低通法去噪存在信号失真问题，综合EMD方法分解、重构方便和小波阈值法灵活、可调的优点，提出一种EMD-小波阈值爆破震动信号去噪方法. 基于某矿地表实测数据，借助EMD的自适应分解特性，在原始信号分解的基础上，识别属于高频噪声的IMF1和IMF2分量，并对其进行小波阈值去噪处理，提取淹没在噪声中的有用特征信息MF1和MF2，最后，将MF1、MF2与剩余IMF分量及余量R进行重构，得到干净信号. 通过频谱和小波包能量分析知： EMD-小波阈值法既能有效去除噪声，又能很好保留真实信号，还可避免EMD分解的端点震荡效应，是一种高效的爆破震动信号去噪方法.
Given the undesirable effect of wavelet threshold denoising as well as signal distortion existing in EMD low-pass denoising，a new method for blasting vibration signal denoising based on EMD-wavelet threshold is proposed in the dissertation，integrating the convenience of decomposition and reconstruction of EMD method together with the flexible and adjustable features of wavelet threshold method. To start with，on the basis of recorded field data in the surface of a mine，identify IMF1 and IMF2，two high-frequency noise components from the decomposed original signal taking advantage of EMD’s adaptive decomposition property. Then，denoise IMF1 and IMF2 with wavelet threshold method before collecting useful characteristics information of MF1 and MF2 drowned in the noise. At last，reconstruct MF1，MF2 with the remanent IMF components and residue R to get the clear signal. Upon analysis on frequency spectrum and wavelet packet energy，it could be concluded that the EMD-wavelet threshold denoising is a proven efficient method for blasting vibration signal de-noising as it can effectively wipe off the noise，protect the real signal while avoiding the endpoint shock effect of EMD decomposition