Magnetotelluric signal spectrum estimation method based on Hilbert-Huang transform
Cai Jian-hua1,2, Tang Jing-tian2
1. School of Info-physics and Geomatics Engineering, Central south University, Changsha City, Hunan Province, 410083, china;
2. Information Institute, Hunan University of Arts and Science, Changde City, Hunan Province, 415000, China
Abstract：Due to the unstable characteristics of magnetotelluric signal,the spectrum method based on the Fourier Transform could bring in deviation. A marginal spectrum estimation method based on HHT was proposed in this paper the marginal spectrum was obtained by Hilbert spectrum integrating along the time axis,it represents amplitude accumulation effect for the whole signal over the time span. In this paper the linear property of the marginal spectrum was proved,two methods which were used to improve the accuracy of the Hilbert spectrum estimation were discussed in detail.The numerical experiments for simulation MT signal and measured MT signal were conducted. The theory and experiments proved that spectrum estimation method which is based on the HHT fits the MT signal better,it could minimize the estimation deviation which was caused by the unstationarity of the MT signal,it also could restrain strong white noise,its frequency resolution and estimation accuracy are higher than Fourier Transform method.
