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Enclosure-Induced Interference Effects in a Miniaturized Sidescan Sonar

Jonsson, Jonas; Lekholm, Ville; Kratz, Henrik; Almqvist, Monica LU and Thornell, Greger (2012) In IEEE Journal of Oceanic Engineering 37(2). p.236-243
Abstract
On, for instance, the miniaturized submersible explorer, Deeper Access, Deeper Understanding (DADU), only 20 cm in length and 5 cm in diameter, the sidescan sonar needs to be tightly mounted in the hull. Finite element analysis (FEA) as well as physical measurements were used to investigate the effects of beam interaction with acoustically nearby rigid boundaries. Computer simulations showed the first major dip in the beam shape to vary in strength, size, and position with the enclosure wall height, from a position of 47 degrees at 0.0-mm wall height to 32 degrees at 3.0-mm wall height. Hydrophonic measurements on the manufactured test device confirmed these values to within 9%, varying between 47 and 29 degrees. In addition, Schlieren... (More)
On, for instance, the miniaturized submersible explorer, Deeper Access, Deeper Understanding (DADU), only 20 cm in length and 5 cm in diameter, the sidescan sonar needs to be tightly mounted in the hull. Finite element analysis (FEA) as well as physical measurements were used to investigate the effects of beam interaction with acoustically nearby rigid boundaries. Computer simulations showed the first major dip in the beam shape to vary in strength, size, and position with the enclosure wall height, from a position of 47 degrees at 0.0-mm wall height to 32 degrees at 3.0-mm wall height. Hydrophonic measurements on the manufactured test device confirmed these values to within 9%, varying between 47 and 29 degrees. In addition, Schlieren imaging was proposed and used as a noninvasive means of qualitative beam shape characterization. A field test was performed with the enclosure height set to 0 and 3 mm. With the latter height, a dark band, corresponding to a sonar sensitivity dip at about 30 in the beam, appeared in the sonar image. It was found that the beam shape is sensitive to small mounting errors, in this case where the wavelength of the sonar is on the same size scale as the enclosure. Furthermore, it was found that FEA models can be used to accurately predict enclosure effects on sonar beam shapes, and Schlieren imaging can be used to visually detect the shape deformations in mounted sonar devices. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Beam shape, finite element analysis (FEA), miniaturize, Schlieren, sidescan sonar
in
IEEE Journal of Oceanic Engineering
volume
37
issue
2
pages
236 - 243
publisher
IEEE--Institute of Electrical and Electronics Engineers Inc.
external identifiers
  • wos:000303326500007
  • scopus:84859910356
ISSN
0364-9059
DOI
10.1109/JOE.2012.2188160
language
English
LU publication?
yes
id
e3d72ff8-7d32-45a5-9e79-6d93cb743cad (old id 2570346)
date added to LUP
2012-06-01 13:43:57
date last changed
2017-01-01 06:27:09
@article{e3d72ff8-7d32-45a5-9e79-6d93cb743cad,
  abstract     = {On, for instance, the miniaturized submersible explorer, Deeper Access, Deeper Understanding (DADU), only 20 cm in length and 5 cm in diameter, the sidescan sonar needs to be tightly mounted in the hull. Finite element analysis (FEA) as well as physical measurements were used to investigate the effects of beam interaction with acoustically nearby rigid boundaries. Computer simulations showed the first major dip in the beam shape to vary in strength, size, and position with the enclosure wall height, from a position of 47 degrees at 0.0-mm wall height to 32 degrees at 3.0-mm wall height. Hydrophonic measurements on the manufactured test device confirmed these values to within 9%, varying between 47 and 29 degrees. In addition, Schlieren imaging was proposed and used as a noninvasive means of qualitative beam shape characterization. A field test was performed with the enclosure height set to 0 and 3 mm. With the latter height, a dark band, corresponding to a sonar sensitivity dip at about 30 in the beam, appeared in the sonar image. It was found that the beam shape is sensitive to small mounting errors, in this case where the wavelength of the sonar is on the same size scale as the enclosure. Furthermore, it was found that FEA models can be used to accurately predict enclosure effects on sonar beam shapes, and Schlieren imaging can be used to visually detect the shape deformations in mounted sonar devices.},
  author       = {Jonsson, Jonas and Lekholm, Ville and Kratz, Henrik and Almqvist, Monica and Thornell, Greger},
  issn         = {0364-9059},
  keyword      = {Beam shape,finite element analysis (FEA),miniaturize,Schlieren,sidescan sonar},
  language     = {eng},
  number       = {2},
  pages        = {236--243},
  publisher    = {IEEE--Institute of Electrical and Electronics Engineers Inc.},
  series       = {IEEE Journal of Oceanic Engineering},
  title        = {Enclosure-Induced Interference Effects in a Miniaturized Sidescan Sonar},
  url          = {http://dx.doi.org/10.1109/JOE.2012.2188160},
  volume       = {37},
  year         = {2012},
}