Experimental Study on Optoelectronic Submarine Cable Used for Ship Radiation Noise Detection

In this study, we connected the DAS (distributed acoustic sensing) system to a 69-km optoelectronic submarine cable located in Hainan, China. A continuous four-day data collection was conducted to assess its potential for monitoring ship radiation noise. The sea depth range of the submarine cable is from 0 to 170 m. By connecting the DAS system, the submarine cable is equivalent to 13,800 strain sensors, with a spatial resolution of 5 m. During the experiments, two 100-ton fishing boats were leased and navigated near the submarine cable using various strategies continuously for more than 24 hours. We combine the data provided by the AIS (Automatic Identification System) to process and analyze the radiation noise signals collected from leased fishing boats and other ships. Experimental results indicate that the submarine cable DAS system can effectively and stably capture the line spectrums of radiation noise from various types of ships, provide a basis for identifying ship types. Furthermore, taking a container ship as an example, we studied the sensing range of submarine cables and the intensity of radiation noise at various frequencies, and used beamforming algorithms to estimate the bearing of the container ship. The root mean squared absolute error of the bearing estimation is 4.29°.