Passive diver detection and localization using hydrophones suspended under a boom
conference paper
A boom is a line of floats that constitutes a physical barrier for providing abovewater stopping power. However, it does not provide any situation awareness. In order to overcome this shortcoming, an integrated “booms and sensors” solution using passive sonar was conceived and tested experimentally by suspending hydrophones under a boom. The conducted study investigated the self-noise of the boom assembly, the motion of the boom and of the hydrophones, and the detectability of divers and boats. Experiments were conducted in late 2011 / early 2012 in Den Helder and in the Port of Rotterdam. The self-noise investigation showed that the boom produces transient signals that dominate the ambient noise on the hydrophone and limits the range of diver detection to about 100 m. This is sufficient to enable detection of an intrusion (i.e. a diver passing under the boom). Mitigation measures were implemented during the deployment of a 96 m boom equipped with 8 suspended hydrophones. The mitigation measures were effective and more than doubled the detection range. Two fixed acoustic sources were used to track the hydrophones motion and allowed localization of divers at 200 m. Tracking of the hydrophones was required to account for their large motion under the boom (up to several meters in a few seconds). A follow up study also demonstrated that the hydrophone tracking can be achieved with the requested accuracy using (surface) RTK GPS, thus enabling a fully acoustically passive operation of the system.
TNO Identifier
483509
Source title
Proceedings of 1st International Conference on Underwater Acoustics (UAC), 23-28 June 2013, Corfu, Greece
Pages
1003-1010
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