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Multipath Reduction of Shaft Tower Monitoring with GPS in Mine

Safe shaft tower operation is an important guarantee for mine production. It’s necessary for monitoring to develop more effective techniques because the traditional measurements are inadequate for the purpose. For this reason, GPS kinematic positioning (RTK) technique was presented to accomplish the task, meanwhile, the main error sources (multipath error) was systematically analyzed. In addition, the Empirical Mode Decomposition (EMD)-Wavelet model was proposed for extracting multipath model. To eliminate the systematic errors, the EMD decomposes the time series to high-frequency part and low-frequency part with the standards of scale selection, which is given in terms of the mean of the accumulated standardized modes, and the tendency of high-frequency part is extracted by Wavelet. Then low-frequency part and the tendency of high-frequency are reconstructed based on EMD theory and the systematic errors mitigation model is demonstrated as well. The scheme of the multipath error reduction based on the EMD-Wavelet is suggested. The experiment shows that the proposed scheme dramatically improves the precision of dynamic coordinate series about 40-70% after multipath error mitigation.