Based On Emd When The Frequency Analysis And Filtering

The time-frequency analysis methods, which are applied in non-linear and non-stationary signal processing and analysis quickly and efficiently, have become a hot topic of modern signal processing methods study field. It gradually shows that there are many advantages of EMD (Empirical Mode Decomposition) in the field of non-linear and non-stationary signal processing. EMD decomposes a complex signal into a finite number of IMF (Intrinsic Mode Functions), and EMD is a high frequency resolution and adaptive method. In this paper, the entire theoretical systems of empirical mode decomposition have been researched deeply, focused on the filtering methods based on EMD and EMD application of time-frequency analysis. Furthermore, a new filtering method—HHT spectrum filtering method based on wavelet threshold filtering preprocessing is proposed. The main contents are illustrated as follows:(1) The concept of instantaneous frequency is introduced firstly. Then, the basic concepts of IMF and principles of EMD decomposition algorithm are discussed, and the characteristics of the EMD algorithm are analyzed. Combined with IMF, it is given that the physical meaning of the Hilbert marginal spectrum and the Hilbert spectrum are formulated, and the theories of the whole time-frequency analysis are discussed in detail. Besides, the problem of EMD time-frequency method is also analyzed, including modes mixing, end effect, sifting stop condition and so on.(2) Compared to traditional time-frequency analysis methods and used to analyze time-frequency characteristics of numerical results of classical nonlinear equation system and signal singularity detection, The theoretic analysis and simulation experiment results show that EMD spectrum has perfect time-frequency concentration, and high time-frequency resolution characteristics.(3) The three filtering methods: the EMD filtering, wavelet threshold filtering based on EMD and the Hilbert spectrum filtering, are discussed for their advantages and shortcomings. A new filtering method—HHT spectrum filtering method based on wavelet threshold filtering preprocessing is proposed. Through simulation experiments, comparing with EMD filtering, empirical mode decomposition based on the wavelet threshold filtering, wavelet threshold filtering and the Hilbert spectrum filtering, the proposed method is verified its validity and superiority.