Optimal Frequency Design of Marine Electromagnetic Detection System for Small Underwater Targets

Efficient detection of near-seafloor metallic targets poses significant challenges for conventional underwater inspection methods. In this paper, the optimal detection frequency of the marine electromagnetic detection technology for detecting small targets such as unexploded ordnance (UXO), iron pipes, and aluminum pipes on the seabed is simulated and analyzed using the Monte Carlo method. This analysis is based on the electromagnetic response law of the target and the attenuation law of the electromagnetic field in the seawater medium in marine electromagnetic detection technology. The optimal detection frequency band is obtained to be [1807, 5365] Hz. Selecting a single frequency point in this frequency band to construct a series resonant circuit can provide the optimal radiant efficiency of the transmitter. On this basis, a remotely operated vehicle (ROV)-based magnetic detection system was designed, using a coil as the transmitter and a fluxgate as the receiver. The system was verified through sea trials, and the detection distance of small aluminum pipe targets can reach over 1.5 m.