Study On Hilbert-Huang Transform And Its Application

The Hilbert-Huang Transform (HHT) with important theoretical value and broad prospects for application, a new nonlinear and non-stationary signal analysis method developed by N.E.Huang 1998. The key part of this method is the empirical mode decomposition (EMD) method with which any complicated signal can be decomposed into a finite and often small number of intrinsic mode function (IMF). Using Hilbert transform to those IMF components can yield instantaneous frequency;the final presentation of this result is an energy-frequency-time distribution, designated as the Hilbert spectrum.As a new signal analysis theory, HHT has gradually applied to seismic signal analysis, mechanical failure diagnosis, hydrodynamics, medical signal processing, voice signal processing, and so on. Since HHT is still in the preliminary stages of development. Thus there are a number of issues need to be studied and improved. Therefore, this paper analysis and discuss the problems of the HHT, and study on the application of HHT, the results are as follows:1. This paper analyzes HHT with the sampling frequency, termination guidelines, curve fitting, border processing, mode mixed, and so on. And based on the concept of time characteristic scale, a new approach to border processing named extension method based on boundary local characteristic scale is proposed. The approach improves better the impact of boundary effect on EMD.2. HHT is used for the signal processing of power system. And based on the performance of signal break detection under HHT, a fault location method for EHV transmission lines is proposed. Simulation experiments showed that the approach can do better to achieve good positioning and ranging.3. HHT is applied to radar signal processing. An intra-pulse analytical method of radar signal is proposed. Simulation experiments showed HHT is a multi-signal processing method;it can accurately describe the change of instantaneous frequency;and can distinct the intra-pulse modulation types clear between various types of radar signals;and easy to estimate the modulation parameters.