强干扰区含噪电磁场的时空分布特征

Spatial and Temporal Distribution Characteristics of Electromagnetic Fields in Strong Noise Area

噪声是限制电磁勘探应用效果的瓶颈之一,明确含噪电磁场数据的特征是强干扰区开展电磁法研究的首要问题。本文依据庐枞矿集区的干扰源调查及大量实测数据,通过对比不同条件、多种类型的电磁场数据,归纳了强干扰区电磁噪声源的主要类型,并总结了含噪电磁场数据的时间域、频率域及空间分布特征。结果表明:强干扰区噪声源可按多种形式进行分类;含噪电磁场数据在时间域常具有显著的形态、振幅、结构及相关性特征;时频谱常表现出不同的时间分段及频率分带特征;频域响应常呈分频带畸变特征,以"近源"型畸变最为典型;噪声影响的空间分布与场源类型、观测方位及地下结构等因素相关。

Noise is one of the bottlenecks that restrict the application effect of electromagnetic prospecting. Understanding the characteristics of electromagnetic fields is primary for an electromagnetic research in strong noise areas. Based on the investigation of interference sources and a large amount of measured data in Lu-Zong ore concentration area, we summarized the main types of electromagnetic noise sources in strong noise areas, and the distribution characteristics of the noise-containing electromagnetic fields in time, frequency,and space domain by comparing and analyzing various types of electromagnetic field data with different conditions. The results show that the noise sources in Lu-Zong area can be classified into different forms;the data of the noisy electromagnetic fields often have significant morphological, amplitude, structural, and correlative characteristics in time domain;the spectrum figures often show different time and frequency band characteristics;the frequency domain responses often show distortion in certain frequency bands, and the "near source" distortion is the most typical one. The spatial distribution of noise influence is related to the types of field sources, observation orientations, and underground structures. According to the characteristics of noise data, the pertinent processing algorithm or research direction is pointed out, which provides a reference for the application of electromagnetic methods in strong noise areas.