A Heterogeneous, Autonomous Passive Network for Underwater Surveillance: Experimental Results With Real Data Collected at Sea

This article describes a sea trial conducted by the Centre for Maritime Research and Experimentation in the coastal waters of La Spezia, Italy. It presents a selection of the most significant results achieved using the field data collected with an underwater surveillance network of fixed and mobile platforms equipped with advanced passive acoustics sensors. The surveillance network consists of autonomous, long-endurance, low-power, smart sensor nodes capable of automatically generating sonar contacts from acoustic data in real time and of sharing these contacts with the other nodes of the network through acoustic modems. The sonar contacts bring information on time stamp, azimuth, elevation, and frequency of each detected noise source (target). This article focuses on real-time passive detection, localization, and tracking of artificial targets and vessels of opportunity as well as on cooperative autonomy among the mobile assets of the network.