Comparison of the results of digital filters in forward modeling of time-domain electromagnetic data

Authors

Abstract

In electromagnetic data forward and inverse modeling, digital filters are used. A fast digital filter with millions of repeatable calculations is required for two- and three-dimensional modeling. Henkel's transformations are frequently used to model frequency-domain electromagnetic data. In time-domain electromagnetic data modeling, the Henkel, sine and cosine integrals complicate digital filter calculations. The purpose of this paper is to investigate different methods of digital filters for solving time-domain or transient electromagnetic (TDEM or TEM) problems. All common methods were fully coded in "MATLAB" software package, and the outcomes were examined. Then, their modeling results were compared with direct analytical solution and layered earth models, and finally, with the results of the "CR1MD" modeling software. This study shows that while the outputs of digital filtering methods usually overlap, increasing the number of coefficients does not necessarily increase calculation accuracy. The 61 coefficients of the "Kong" method produce better results compared to other digital filtering methods investigated in this research work. The results have also shown that the fast sine transformation method is not suitable for forward and inverse modeling due to its poor end-channel results. However, the numerical sine transformation method and "Key" digital filters can be used in TDEM data modeling.  

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References

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Volume 8, Issue 4
October 2030
Pages 273-286

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