Research on VMD Detection Method of Underwater Ferromagnetic Targets Based on Industrial Frequency Electromagnetic Fields

Today, many countries around the world attach great importance to the exploitation of underwater resources and the economic significance of underwater shipwreck detection technology. The common targets for detecting underwater ferromagnetic targets that exist underwater and in the ocean include artificial reefs, submarine pipelines, and underwater metallic mineral resources, etc. The means for detecting these targets are generally sonar detection, satellite positioning, optical detection, radar, and geomagnetic anomalies. The means of detecting these targets are generally: sonar detection, satellite positioning, optical detection, radar and geomagnetic anomaly detection. However, as the water depth increases, the underwater pressure increases, the signal of these targets will be affected by the interference of the marine medium to make its attenuation distortion, and at the same time, the underwater geological environment, temperature, ocean currents and other factors will make the signal become very weak. These traditional means of detection is difficult to detect these weak signals, such as acoustic detection to arrange a large number of detection arrays. Radar detection is ineffective in penetrating water, making it difficult to detect underwater targets that are too deep. Optical detection requires fibre optic cables that are relatively difficult to construct underwater. In order to solve these problems, more efficient means of detection need to be found.. Now all countries in the world have built different large-scale power transmission networks, these transmission networks will radiate different frequencies of industrial frequency electromagnetic fields and industrial frequency electromagnetic waves to space, generally 50 Hz or 60Hz. the frequency of industrial frequency electromagnetic waves are not easy to be affected by seawater and other environmental media attenuation. Therefore, this property can be exploited for the detection of underwater ferromagnetic targets. This paper focuses on whether the characteristics of VMD decomposition can be changed when the interaction between the industrial frequency electromagnetic field and the underwater ferromagnetic target occurs. According to the experiments, it is shown that the characteristic of VMD changes obviously, so this characteristic is used to successfully extract the target signal of underwater ferromagnetic objects from the signals collected in the external field experiment, which provides a new method for the detection of underwater ferromagnetic target signals by the industrial frequency electromagnetic field.