Research on Properties of Hilbert Spectrum

Hilbert-Huang transform (HHT) is a new method of processing non-stationary signals. The method consists of two parts: the empirical mode decomposition (EMD), and the Hilbert spectral analysis. HHT method is introduced. Some properties of it are presented. Firstly, Hilbert spectrum is linear, and it satisfies the principle of superposition without the cross-term interferences which exist in Wigner-Ville distribution. Secondly, Hilbert spectrum has local property, and compared to wavelet analysis, it has excellent time-frequency conglomeration. In addition, Hilbert spectrum has real number property. Finally, it has the adaptive frequency multi-resolution property. Examples from simulation experiment are given to demonstrate the power of the properties. These properties are of great importance to its application in measurement data processing.