Directly-Mean EMD Of Four-Midpoint Estimation Method And Research On Hilbert Spectrum Of Waves Signal

EMD/HSA method is established by Huang suitable for non-stationary, nonlinear signal.Indigital signal processing,it is more efficient than traditional signal processing method.It canreflect the signal more local nature.It is now in the waves signal, seismic signal, biomedical signaletc a wide range of applications.EMD/HSA method includes two parts, empirical mode decomposition(EMD) and hilbertspectrum analysis(HSA). Among them, the empirical mode decomposition method is thefoundation of the hilbert spectrum analysis. The sifting process is used in the EMD method.In thesifting process,it has to calculate the mean of upper and lower envelope. It needs two cubic splineline to get upper and lower envelope. However,the directly-mean EMD method by Zhongcalculate the mean of upper and lower envelope directly by midpoints.It can reduce computecapacity and improve compute accuracy.However,the directly-mean EMD method is just a good idea.It did not give method to treatboundary effect,and it did not give method to treat signal which has less extreme points. Thisarticle gets a new method,the directly-mean EMD of four-midpoint estimation method,by addingfour midpoints based on directly-mean EMD method.Because of expands the xcoordinate ofsignal in decomposite process, it removes boundary effect of EMD completely.This article alsogives methods to treat signal which has less than four extreme points.This method can be usedconveniently.Use directly-mean EMD of four-midpoint estimation method on waves signal etcdecomposition, it decomposite the signal quickly,and the intrinsic mode functions(IMF) has noboundary effect, and has no confusion phenomenon.So this decomposition method is practicabilityand effectiveness. After decomposite by the directly-mean EMD of four-midpoint estimationmethod,this article does hilbert spectrum analysis.It can easily analyze the signal on frequency andvibration of the time.This paper also compare this method with FFDSI method of Zhang. Use two methods todecomposite the same waves signal,do the same hilbert spectrum analysis,it gets the difference ofthese two methods.User can depend on its purpose to choose suitable method. This paper also usec sharp and matlab to build a software,which can do EMD/HSA easily.