Underwater sensor systems for harbour and base protection - final report

This report is the final report of the R&D project "Underwater sensor systems for harbour and base protection" that has been carried out during the years 2007 to 2009. The work in the project has been focused on detection of small underwater threats using a network of underwater sensors in harbours or naval bases. Specifically, we have studied how passive trip-wires equipped with hydrophones and electrode sensors could be used as a complement to active sonar systems. A constrain is that the systems should be usable both for surveillance in at home as well as during international operations. Hence, the studied systems should be flexible and easily deployable in order to meet multiple threats in various areas. We have studied methods for passive detection, classification and tracking. It has also been investigated how fusion methods can be used to form unified decisions of the whole system, which have potential to become both more accurate and more robust compared with decisions based on single sensors. Detection depths for a lidar system against shallow underwater targets have also been investigated. Finally, the field of active sonar systems for harbour surveillance has been monitored in order to gain knowledge about capabilities and limitations of such systems.