Hilbert-Huang变换在瞬变电磁去噪中的研究与应用

Study on transient electromagnetic method of denoising based on Hilbert-Huang transform

瞬变电磁法(TEM)是电法勘探的一个重要分支,具有受地形影响小、工作效率高、对低阻体分辨率高纯异常测量等优点.在野外数据采集过程中,瞬变电磁数据容易受到周边环境噪声的干扰.由于瞬变电磁的晚期信号能量弱,极易被噪声淹没,使得数据处理过程中出现假异常.为了更好地减弱噪声的影响,剔除假异常,得到真实的地下介质信息.本文把Hilbert-Huang变换(Hilbert-Huang Transform,简称HHT)方法应用到瞬变电磁数据处理中,通过对含有噪声的瞬变电磁仿真数据进行经验模态(Empirical Mode Decomposition,EMD)分解、重构,得到了真实的电磁信号,证明HHT方法在瞬变电磁去噪中可行.最后对TEM实测数据进行EMD分解、重构,结果表明该方法能够有效的压制噪声的干扰,突出TEM真实信号,较好的识别异常体的位置,提高TEM解译结果的准确性.

As an important branch of electrical prospecting,Transient Electromagnetic Method(TEM)has the advantages of small topographic influence,high efficiency,high resolution for low resistivity body and pure abnormal measurement.However,during the acquisition process of measured data,TEM is also vulnerable to all kinds of noise interference,especially for later-times data,because of low energy and weak signal,the existence of noise seriously will influence the useful signal,therefore,easy to cause false anomalies in the data processing.In order to weaken the influence of noise and eliminate the false anomalies,at the same time,obtain real underground medium information.In this paper,Hilbert-Huang Transform(HHT)is introduced into TEM data processing and proved feasible through Empirical Mode Decomposition(EMD)decomposition and reconstruction of TEM data to obtain real electromagnetic signal.Finally,through EMD decomposition and reconstruction of measured TEM data,it is proved that this method can effectively suppress the interference of TEM noise,identify the location of abnormal body and improve the accuracy of the results.