Multiswath multibeam echosounder for efficient seabed backscatter imaging and classification

MULTISWATH MULTIBEAM ECHOSOUNDER FOR EFFICIENT SEABED BACKSCATTER IMAGING AND CLASSIFICATION

1. Didier Charlot⁽¹⁾,Philippe  Alain⁽¹⁾, Géraldine Duffait⁽²⁾ ,Olivier Lerda⁽²⁾, Guillaume Matte⁽²⁾

 (1) iXBlue Sonar System Division, 256 rue Rivoalon, 29200 Brest,  France

(2) iXBlue Sonar System Division, 46 Quai F. Mitterrand, 13600 La Ciotat, France.

 

               Managing marine resources and habitats require a classification system to identify and characterized seabed properties. Acoustic systems are recognized to be remote sensing tools that measure efficiently sediment properties and seabed morphology [1].Single beam, multibeam echosounder and sidescan sonar systems are commonly used to characterize seabed type by respectively analyzing echo strength returns, backscatter (BS) angular response, and texture analysis. Multibeam  (and interferometric sidescan ) systems  have the great advantage to measure the bottom bathymetry hence the true grazing angle at least in the across track direction. But there are still some challenges to face to get a robust calibrated BS value. 

First, standard multibeam systems  do not measure directly the full BS backscatter angular response on each soundings. This can be accomplished by using a dual axis multibeam to record the BS in the along track direction[2]. The BS angular response is  a powerful metric to characterize the sediment type. 

Second, the BS response is sensitive to the insonification direction (azimuth) and this dependency should also be considered to improve calibration procedure.  Recently, a full 3D steerable high resolution multibeam system has been developed [3]. First investigation ([3],[4]) have shown the high potential of multiswath multibeam system. With the 3D steerable swath capability, the bidirectional BS angular response can be recorded on each insonified soundings. This presentation will emphasize recent advances in processing using the  full multiswath multibeam capabilities.

 

References:

[1] John T. Anderson, Editor,”Acoustic Seabed Classification of Marine Physical And biological Landscapes”, ICES Report N° 286, August 2007

[2]M.  Gutberlet and H. W. Schenke ,“HYDROSWEEP : New Era in High precision bathymetric Surveying in Deep and Shallow water” , Marine Geodesy,1989, Vol13,pp1-23

[3] F. Mosca & al., “Scientific potential of a new 3D multibeam echosounder in fisheries and ecosystem research”, Fisheries Research 178 pg. 130-141, 2016.

[4] Nguyen, Trung Kiên , Charlot D. , Boucher  J.-M , Le Chenadec G.,  Fablet R., “Seabed classification using a steerable multibeam echo sounder”. Oceans 2016 MTS/IEEE 2016,Monterey

[5] Nguyen, Trung Kiên, ”Seafloor classification with a multi-swath multi-beam echo sounder”, PhD thesis 2017, IMT Atlantique; http://www.theses.fr/2017IMTA0035