Effects of using inclined parametric echosounding on sub-bottom acoustic imaging and advances in buried object detection.

Schneider von Deimling, Jens, Held, Philipp, Feldens, Peter and Wilken, Dennis (2016) Effects of using inclined parametric echosounding on sub-bottom acoustic imaging and advances in buried object detection. Open Access Geo-Marine Letters, 36 (2). pp. 113-119. DOI 10.1007/s00367-015-0433-3.

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Abstract

This study reports an adaptation of a parametric
echosounder system using 15 kHz as secondary frequency to
investigate the angular response of sub-bottom backscatter
strength of layered mud, providing a new method for enhanced
acoustic detection of buried targets. Adaptions to
achieve both vertical (0°) and non-vertical inclination (1–
15°, 30°, 45° and 60°) comprise mechanical tilting of the
acoustic transducer and electronic beam steering. Data were
acquired at 18 m water depth at a study site characterized by a
flat, muddy seafloor where a 0.1 m diameter power cable lies
1–2 m below the seafloor. Surveying the cable with vertical
incidence revealed that the buried cable can hardly be discriminated
against the backscatter strength of the layered mud.
However, the backscatter strength of layered mud decreases
strongly at >3±0.5° incidence and the layered mud echo pattern
vanishes beyond 5°. As a consequence, the backscatter
pattern of the buried cable is very pronounced in acoustic
images gathered at 15°, 30°, 45° and 60° incidence. The size
of the cable echo pattern increases linearly with incidence.
These effects are attributed to reflection loss from layered
mud at larger incidence and to the scattering of the 0.1 m
diameter buried cable. Data analyses support the visual impression of superior detection of the cable with an up to
2.6-fold increase of the signal-to-noise ratio at 40° incidence
compared to the vertical incidence case.

Document Type: Article
Additional Information: WOS:000372910200003
Keywords: sub-bottom, acoustic imaging, parametric echosounding, seafloor classification, cable tracking, RV Littorina
Research affiliation: OceanRep > The Future Ocean - Cluster of Excellence > FO-R03
OceanRep > The Future Ocean - Cluster of Excellence > FO-R05
Kiel University > Kiel Marine Science
OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Kiel University
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1007/s00367-015-0433-3
ISSN: 0276-0460
Projects: Future Ocean, MaTeP
Date Deposited: 08 Dec 2015 12:43
Last Modified: 06 Feb 2019 11:55
URI: http://oceanrep.geomar.de/id/eprint/30453

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