Feasibility of signal enhancement with multiple grounded‐wire sources for a frequency‐domain electromagnetic survey

作者：Haigen Zhou, Yao Yao, Changsheng Liu, Jun Lin, Lili Kang, Gang Li, Xinsen Zeng · 发表于：Geophysical Prospecting · 年份：2017 · DOI：10.1111/1365-2478.12596 · 被引用次数：28 · 研究领域：Geophysical and Geoelectrical Methods、Geophysical Methods and Applications、Seismic Waves and Analysis

ABSTRACT Frequency‐domain electromagnetic methods with a grounded‐wire source are powerful tools in geophysical exploration. However, the signal may be too weak to guarantee the quality of survey data in complex electromagnetic environments, especially when the receiver is located in the air for the newly developed grounded‐source airborne frequency‐domain electromagnetic method. In this paper, a signal enhancement method with multiple sources is proposed to solve this problem. To evaluate the signal enhancement effect, we compared the signals generated by a single source and multiple sources with equal electric moment. The signal differences caused by synchronisation error and separation distance between source elements were analysed, and the methods to achieve maximum signal were introduced. Besides, we discussed the interaction between adjacent source elements to ensure the system safety, including the changes in output current and the safe distance between two sources using a dual‐source model. Lastly, a comprehensive field experiment was designed and conducted to test the multiple‐source method. The data processing results are comparable for single and dual sources, and the signal‐to‐noise ratio of dual source is higher in the field test. The subsurface resistivity structure at the test site is consistent with the previous controlled‐source audio‐frequency magnetotellurics method. These results show that signal enhancement with multiple sources is feasible. This study pr...