Computer Simulation Study On Hilbert-Huang Transform Technology

Signal analysis is a necessary part in scientific research and practical applications. In recent years, as a new hot point of signal processing, more and more people put emphasis on Time-frequency analysis method. In this paper, as a new method, the Hilbert-Huang Transform Technology (HHT) has been introduced. Starting from the concept of the instantaneous frequency, the intrinsic mode functions which made the instantaneous frequency meaningful, and the way how to realize the Empirical Mode Decomposition (EMD) has been introduced. The final presentation of HHT result is in 3D of time-frequency-energy/amplitude distribution, which defined as the Hilbert spectrum. Hilbert spectrum has been compared with the Fourier spectrum. The definition of time scale have been discussed, which make us to understand that HHT is based on the local nature of the signals; there are two ways to reduce the end effects, one is the prediction of the end points, another is the calculation of the instantaneous frequency. Some methods have been tried to solve the end problems.The application of HHT is in the last part of the paper. The analog modulating signals have been analyzed using HHT, including the amplitude modulation and angular modulations. The nonlinear system defined by the duffing equation has also been analyzed, a comparison between the way that the system has outside force and the way otherwise. Moreover, the data from experiments has also been studied by using HHT. As a comparison, all the examples in the paper have also been analyzed by the Morlet wavelet method. Comparison results show that HHT is more effective and precise in analysis of time and frequency.