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摘要
The amount of information that the different Cu2+ contents in soil are mapped to the soil spectra is very weak, and the noises in the hyperspectral data are also very difficult to avoid. Thus the sky point of the research would be how to extract the weak Cu2+ information from the complex noise environment of soil spectra. The empirical mode decomposition (EMD) algorithm can effectively remove the noise in hyperspectral data. Further more, the EMD is the premise of Hilbert transform that is a kind of time-frequency analysis on nonlinear and unstable signal. Therefore the time-frequency analysis algorithm on Hilbert-Huang transform (HHT) could be used for de-noise processing and information extracting of the soil spectra after the Huang transform is introduced. In this paper, through the HHT was applied in time-frequency to analyze the soil spectra polluted by different Cu2+ concentrations, and the information mining of Cu2+ pollution in soil spectra was achieved based on the curves such as envelope, modulation signal and frequency spectrum of each intrinsic mode IMF) component that could be decomposed out from the original soil spectra by EMD. The study results showed that, the analyzing results of soil spectra were identical based on the time-frequency HHT when the soil was polluted by same Cu2+ concentrations, but non-identical when polluted by different Cu2+ concentrations, so that the Cu2+ content in soil can be also retrieved based on the IMF components. Accordingly, the HHT analysis in time-frequency provides a new method and idea for information extracting, spectral diagnosing and Cu2+ content retrieving of soil spectra.
- 出版日期2018-2
- 单位中国矿业大学（北京）
