Discussion On The Application Of Decomposing-frequency Hilbert-Huang Transform To Non-stationary Signal

Hilbert-Huang transform(HHT) is a new time-frequency analytic method to analyzethe nonlinear and non-stationary signal. The key step of this method is the empiricalmode decomposition(EMD) method with which any complicated data set can be decom-posed into a finite and often small number of intrinsic mode functions(IMF). Using Hilberttransform to those IMF components can yield instantaneous frequency. The final presen-tation of this results is an energy-frequency-time distribution,designated as the Hilbertspectrum.The EMD method is adaptive and highly e?cient, meanwhile, this method mayrun into di?culties when the data contain intermittence which will cause mode mixing.This paper invokes the wavelet filter technology into the EMD, constructs decomposing-frequency EMD method. With the application of the wavelet filter and EMD methodto the shifting process can yield di?erent scale frequency decomposition of signal, whichis decomposing-frequency intrinsic mode functions. The decomposing-frequency EMDmethod can e?ciently overcome the mode mixing.The combination of the decomposing-frequency EMD and the Hilbert spectrummethod sets up the decomposing-frequency Hilbert-Huang transform, which can providemore physically meaningful interpretation of nonlinear and non-stationary processes thanwavelets transform.This paper demonstrates the use of decomposing-frequency Hilbert-Huang trans-form method to analyze the earthquake motion. By using the method, time-frequencycharacteristics of the earthquake ground motions are analyzed. Compared to using thewavelets transform method to the same time-series, those results can clarity the advanceand e?cient of the decomposing-frequency Hilbert-Huang transform method.