Developments in sonar and array technologies

Sonar and Array Technologies have been developed over more than 100 years. This paper will give an exposition of this development with emphasis on the most recent one. However, tracks to earlier sonar types will be illuminated. Demands to sonar and arrays will be discussed, and an exposition will be given of the state-of-the-art in single-beam and multi-beam sonar, in side-scan and in synthetic aperture sonar, in ADCP, in sonobuoys and in variable depth sonar. Array types like the SURTASS-LFA and the towed array will also be enphasized. Applications of sonar and arrays for underwater activities will be discussed like for instance seafloor excavation, laying of cables and tubes, off-shore oil-, gas- and mineral-production, hydrography and bathymetry, underwater archaeology, fishery and biomass studies, naval applications like ASW, mine- and torpedo-hunting, studies of underwater structures in harbours and investigations of wrecks. Finally, a brief exposition will be given of today´s threat picture in harbours and in waterways, of the countermeasures and the technologies related to WaterSide Security. The paper will finish with a short presentation of the-state-of-the-art in sonar based on the parametric acoustic array principles.