Unmanned Aerial Vehicle Aeromagnetic Positioning Method for Nearshore Submarine Cables Based on Power Frequency Magnetic Characteristics

Aiming at the technical bottleneck of high-precision detection and positioning of the “last mile” of nearshore submarine cables, this study proposed a comprehensive unmanned aerial vehicle(UAV) aeromagnetic detection method integrating the analysis of power frequency magnetic field characteristics. Firstly, a forward model of the power frequency magnetic field of submarine cables was established, and the propagation and attenuation law of the power frequency magnetic characteristic signal of the cables was revealed through numerical simulation. Secondly, an innovative frequency-domain signal extraction algorithm based on power frequency magnetic characteristics was constructed, effectively improving the recognition accuracy of weak magnetic signals in the background of strong environmental noise. Then, a reverse analytical positioning method combined with the geomagnetic direction was proposed to achieve the meter-level spatial inversion of the direction of submarine cables. The experiment adopted the self-developed ultra-low-altitude(flight altitude of 1 meter) rotorcraft UAV magnetic detection system to conduct actual measurement and verification in the coastal waters of Wenzhou City. The results show that the system effectively conducts aerial magnetic detection operations of power frequency magnetic characteristics under the complex terrain conditions of the intertidal zone. Through comparative analysis, it is found that the power frequency characteristic positioning method has significant advantages over the conventional magnetic anomaly positioning method in the nearshore shallow water area. Its positioning error does not exceed 1.8 meters, and it can accurately track the cable burial path. This research provides a new technical paradigm for the inspection and positioning of submarine cable projects.