Transient electromagnetic (TEM) detection has been widely used in the fields of mineral resources exploration, hydrogeological survey and engineering survey, but electromagnetic interference can lead to late signal distortion, so it has become an urgent problem to suppress the electromagnetic noise of TEM signal and improve the interpretation accuracy of TEM signal. For the first time, this paper introduces the approach of variational mode decomposition (VMD) into the field of TEM signal-noise reduction. The half homogeneous space model and the three-layer earth model were constructed to compare the noise reduction effect of the empirical mode decomposition (EMD) approach and the VMD approach on the three main noises (random noise, power frequency noise, and sferics noise) in the TEM signal. The results are compared with the wavelet threshold denoising approach to verify the superiority of the VMD approach relative to the EMD approach. The results show that the VMD approach is better than the decomposition result of the EMD approach in the signal-noise separation of TEM signals. In addition, the VMD approach is applied to the measured TEM data in a region in southern Shanxi Province, which effectively improves the quality of TEM signals. This indicates that the VMD approach is expected to be used for signal interference suppression in the field of TEM detection in the future.

中文翻译：

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基于经验模式分解和变分模式分解的瞬态电磁信号降噪对比研究

瞬态电磁（TEM）探测已广泛应用于矿产资源勘探、水文地质调查和工程勘察等领域，但电磁干扰会导致后期信号失真，因此抑制TEM信号的电磁噪声和提高TEM信号的解释精度。本文首次将变分模式分解（VMD）方法引入到TEM信号降噪领域。构建半均匀空间模型和三层地球模型，比较经验模态分解（EMD）方法和VMD方法对三种主要噪声（随机噪声、工频噪声和sferics噪声）的降噪效果在 TEM 信号中。将结果与小波阈值去噪方法进行比较，以验证 VMD 方法相对于 EMD 方法的优越性。结果表明，VMD方法在TEM信号的信噪分离方面优于EMD方法的分解结果。此外，将VMD方法应用于山西南部某地区实测TEM数据，有效提高了TEM信号的质量。这表明VMD方法有望在未来TEM检测领域用于信号干扰抑制。将VMD方法应用于山西南部某地区实测TEM数据，有效提高了TEM信号的质量。这表明VMD方法有望在未来TEM检测领域用于信号干扰抑制。将VMD方法应用于山西南部某地区实测TEM数据，有效提高了TEM信号的质量。这表明VMD方法有望在未来TEM检测领域用于信号干扰抑制。