Abstract
To better retain useful weak low-frequency magnetotelluric (MT) signals with strong interference during MT data processing, we propose a SVM-CEEMDWT based MT data signal-noise separation method, which extracts the weak MT signal affected by strong interference. First, the approximate entropy, fuzzy entropy, sample entropy, and Lempel-Ziv (LZ) complexity are extracted from the magnetotelluric data. Then, four robust parameters are used as the inputs to the support vector machine (SVM) to train the sample library and build a model based on the different complexity of signals. Based on this model, we can only consider time series with strong interference when using the complementary ensemble empirical mode decomposition (CEEMD) and wavelet threshold (WT) for noise suppression. Simulation results suggest that the SVM based on the robust parameters can distinguish the time periods with strong interference well before noise suppression. Compared with the CEEMDWT, the proposed SVM-CEEMDWT method retains more low-frequency low-variability information, and the apparent resistivity curve is smoother and more continuous. Moreover, the results better reflect the deep electrical structure in the field.
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This research was funded by the National Key R&D Program of China (No. 2018YFC0603202), the National Natural Science Foundation of China (No.41404111), Natural Science Foundation of Hunan Province (No.2018JJ2258) and Hunan Provincial Science and Technology Project Foundation (No. 2018TP1018).
Li Jin, Doctor, Associate Professor, he received his Bachelor’s degree and Master’s degree from Hunan Normal University in 2003 and 2006, respectively. In 2012, he received a Doctor’s degree in Earth Exploration & Information Technology from Central South University. He is interested in magnetotelluric noise suppression and signal-noise identification.
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Li, J., Cai, J., Tang, JT. et al. Magnetotelluric signal-noise separation method based on SVM–CEEMDWT. Appl. Geophys. 16, 160–170 (2019). https://doi.org/10.1007/s11770-019-0760-7
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DOI: https://doi.org/10.1007/s11770-019-0760-7