HYDROGRAPHIC SURVEY
Fig. 1. SAS improves on the range, resolution and positioning of conventional SSS by advanced digital signal processing.
Operating synthetic aperture sonar
Dominic Koe reports on the advtanges of using synthetic aperture sonar.
S
ynthetic aperture sonar (SAS) improves on the range, resolution and positioning of conventional SSS by
advanced digital signal processing. iXSurvey has purchased a SHADOWS SAS (synthetic aperture sonar) system manufactured by IXSEA SAS. Resolution approaches 500kHz quality but at up to 300m range with sub-metre positional accuracy. A real time georeferenced ‘mosaic’ of the seabed is
produced. A forward looking ‘Gap Filler’ sonar is used to image directly beneath the fish, negating the need for 200 per cent coverage and halving survey time. Te ability of a of a conventional SSS to
resolve a discrete seabed target is controlled by beam width and pulse length; add to this uncertainty in the position, heading, roll and pitch of the towfish and errors increase still further. To illustrate, a conventional sidescan with
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