Abstract. Marine controlled-source electromagnetic method has more and more applications in ocean resources exploration. Electromagnetic transmitter sends electromagnetic wave to the underground, the receiver located on the seafloor receives the electromagnetic wave which carries the information of the geosphere. And the underground structure is obtained by inversion calculation. Data quality of electromagnetic transmitter and seafloor receivers is the most important part of this method. The quality level of transmitting current directly affects the signal-to-noise ratio (SNR) of the electromagnetic field data, as received by a multi-component electromagnetic receiver from the seabed. Although the transmitting current stability is sufficient under normal circumstances, the SNR of the received signal can change owing to factors such as outside noise. In some emergency cases such as instrument failure or a sudden increase in electromagnetic interference that we are not aware of, the frequency and properties of the transmitting current may change, such as its size and waveform. The traditional current monitoring and data playback tools fail to detect and evaluate the anomalies well and in a timely manner, which introduces considerable errors in the later data processing procedure. Pertaining to these issues, this paper proposes a comprehensive quality evaluation method for the transmitting current. The proposed algorithm, based on the analytic hierarchy process, is first used to analyse five current stability parameters: current frequency, positive amplitudes, negative amplitudes, discrepancy of ideal waveform, and waveform repetition and then to define the harmonic energy and calculate the quality of transmitting current (QTC) index of the final data to assess the quality of the transmitting current comprehensively. The results of a marine experiment performed in 2016 show that the algorithm can identify abnormal current data and quantitatively evaluate the current conditions. Under normal circumstances, the QTC index is within 2 %. However, after the simulation of anomalous mutations of the various attributes, the QTC index synchronized mutations to more than 4 % and some curvilinear features were observed. These results will provide a positive, significant guide for the evaluation and monitoring of transmitting current data in marine experiments.
Research on Quality Evaluation Method of TRD Cement-soil Continuous Wall Based on Analytic Hierarchy Process
