基于经验模态分解的瞬变电磁信号的属性提取与分析解释

摘要

瞬变电磁法仅用时域资料进行分析与解释是不充分的,应该将信号的频率成分也综合利用起来进行分析解释.将Hilbert-Huang变换引用到瞬变电磁信号的分析中,将含噪的瞬变电磁信号通过经验模态分解成若干个固有模态函数,对每个固有模态函数进行Hilbert-Huang变换,获得瞬时幅度和瞬时频率,将每个测点的瞬时属性组合起来绘制瞬时振幅剖面图和瞬时频率剖面图,不同构造形态的地质体在两者的剖面图中均有明显的异常反映.各种模型和实例计算表明:用Hilbert-Huang时频分析方法提取瞬变电磁信号的瞬时属性意义明确而且分辨率高,明显优于传统分析解释方法.%Only time domain TEM analysis and interpretation of data are not sufficient,frequency components of the signal should be also utilized for analysis and interpretation.This article introduces the Hilberlt-Huang transform analysis of transient eletromagnetic signals.The noise of the transient electromagnetic signal decomposes into a number of intrinsic mode function through EMD,then extracts from intrinsic mode function of the instantaneous amplitude and instantaneous frequency.Each measuring point of the instantaneous attributes combines instantaneous amplitude drawing and instantaneous frequency section profile.Different structural features of geological in profile are obviously abnormal amplitude and frequency of anomalies.A variety of models and practical examples of the calculations show that HHT method can extract instantaneous attributes of transient electromagnetic signals with clear and high resolution,significantly better than conventional TEM analysis and interpretation.