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Feasibility of signal enhancement with multiple grounded‐wire sources for a frequency‐domain electromagnetic survey
Author(s) -
Zhou Haigen,
Yao Yao,
Liu Changsheng,
Lin Jun,
Kang Lili,
Li Gang,
Zeng Xinsen
Publication year - 2018
Publication title -
geophysical prospecting
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.735
H-Index - 79
eISSN - 1365-2478
pISSN - 0016-8025
DOI - 10.1111/1365-2478.12596
Subject(s) - signal (programming language) , computer science , frequency domain , noise (video) , signal processing , regional geology , field (mathematics) , current source , electronic engineering , acoustics , telecommunications , electrical engineering , geology , physics , engineering , current (fluid) , hydrogeology , artificial intelligence , mathematics , radar , geotechnical engineering , metamorphic petrology , pure mathematics , image (mathematics) , computer vision , programming language
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 provides guidance to the application of multiple sources in field surveys when the survey environment is complex and rigorous.