RUMBLE-2 Project : Rapid Environment Assessment of Sea Bottom Parameters Using an Operational Active Low-Frequency Sonar

This paper presents the European Defence Agency project called “RUMBLE 2” carried out with contribution of several European organizations: TUS in France, TNO in the Netherlands, KDS and FFI in Norway, FOI in Sweden. The objective was to assess the capability of an operational Low Frequency Active Sonar (LFAS) to estimate bottom parameters in shallow water necessary to predict LFAS performance. An inversion method based on the observation of broadside beam reverberation power decay received on a towed array was developed by TNO and applied to experimental results obtained in the North Sea. The result of the inversion is a real time mapping of sea bed parameters, used for improving the prediction of the sonar performance. A demonstrator has been realized, mounted onboard a new Norwegian frigate, using a CAPTAS triplet array sonar and tested at sea. Satisfying agreement with ground truth has been obtained over the set of investigated data. Experimental results lead to a good description of the sea bed reverberation parameters in real time resulting in improved sonar performance predictions. During sea trials, the demonstrator has shown its capability to be used during standard missions of the frigate.