Marine controlled-source electromagnetics-based technology for generating arbitrary-frequency waveforms
WANG Jie1(), WANG Meng1,2(), REN Zhi-Bin1, WANG Chen-Tao1, WANG Hui-Min1
1. School of Geophysics and Information Technology, China University of Geosciences (Beijing), Beijing 100083, China 2. Key Laboratory of Intraplate Volcanoes and Earthquakes, Ministry of Education, China University of Geosciences (Beijing), Beijing 100083, China
Marine controlled-source electromagnetics (MCSEM) is used to explore resources such as oil and gas hydrates, as well as deep geological structures, by revealing resistivity differences below the seabed. Different excitation frequencies correspond to varying detection depths. To enhance the resistivity imaging of targets beneath the seabed, this study investigated the MCSEM-based technology for generating arbitrary-frequency waveforms to flexibly alter the excitation frequency and improve the exploration effectiveness and efficiency. Using the direct digital frequency synthesis (DDS) chip AD9833 and the joint control of a microcontroller and a complex programmable logic device (CPLD), this study achieved the generation of arbitrary-frequency waveforms with limited precision. The test results indicate that this technology can effectively enhance the spectral adaptability and flexibility of MCSEM.
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