Spectral electrical impedance tomography (sEIT) is a promising method to image the subsurface complex resistivity distribution in a broad frequency range (i.e. mHz to kHz). However, inductive coupling between cables is known to affect measurement accuracy for frequencies above 50 Hz. Previous studies have proposed correction methods, but these have not been widely adopted yet. In this study, we evaluated the influence of inductive coupling on the measured complex impedance for different electrode and cable configurations. We propose a novel index to evaluate the inductive coupling strength and use it to develop a filter that selects data with limited inductive coupling. In a first step, the inductive coupling strength of a fan-shaped and parallel cable layout were evaluated. It was found that the fan-shaped layout provided more measurements with low inductive coupling strength. Using a synthetic modelling study with a fan-shaped cable layout, we then showed that it is possible to achieve good inversion results without data correction if measurements with high inductive coupling strength are filtered out before inversion. In a final step, we use the novel filtering approach based on inductive coupling strength with actual surface sEIT measurements. The EIT inversion results based on the filtered data corresponded well with inversion results using data corrected for inductive coupling and also showed good spectral consistency. It was concluded that it is possible to achieve reliable inversion results without data correction for inductive coupling when a fan-shaped layout and configurations with sufficiently low inductive coupling strength are used.

中文翻译：

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减少频谱电阻抗层析成像（sEIT）测量中的电感耦合的实验设计

频谱电阻抗层析成像（sEIT）是一种有前途的方法，可以在很宽的频率范围（即mHz至kHz）中成像地下复合电阻率分布。但是，已知电缆之间的电感耦合会影响50 Hz以上频率的测量精度。先前的研究提出了校正方法，但是这些方法尚未得到广泛采用。在这项研究中，我们评估了电感耦合对不同电极和电缆配置下测得的复阻抗的影响。我们提出了一种新颖的指标来评估感应耦合强度，并使用它来开发一个筛选器，该滤波器选择感应耦合受限的数据。第一步，评估了扇形和平行电缆布局的感应耦合强度。发现扇形布局提供了更多的测量，且电感耦合强度较低。使用带有扇形电缆布局的综合建模研究，我们然后表明，如果在反演之前滤出具有高电感耦合强度的测量结果，则无需进行数据校正即可获得良好的反演结果。最后，我们使用基于感应耦合强度和实际表面sEIT测量的新颖过滤方法。基于滤波数据的EIT反演结果与使用经过电感耦合校正的数据的反演结果非常吻合，并且还显示出良好的光谱一致性。