The University of Southampton
University of Southampton Institutional Repository

Studies into the detection of buried objects (particularly optical fibres) in saturated sediment. Part 2: design and commissioning of test tank

Leighton, T.G. and Evans, R.C.P. (2007) Studies into the detection of buried objects (particularly optical fibres) in saturated sediment. Part 2: design and commissioning of test tank , Southampton, UK University of Southampton 70pp. (ISVR Technical Report, 310).

Record type: Monograph (Project Report)

Abstract

This report is the second in a series of five, designed to investigate the detection of
targets buried in saturated sediment, primarily through acoustical or acoustics-related
methods. Although steel targets are included for comparison, the major interest is in
targets (polyethylene cylinders and optical fibres) which have a poor acoustic
impedance mismatch with the host sediment. This particular report details the
construction of a laboratory-scale test facility. This consisted of three main
components. Budget constraints were an over-riding consideration in the design.
First, there is the design and production of a tank containing saturated sediment. It
was the intention that the physical and acoustical properties of the laboratory system
should be similar to those found in a real seafloor environment. Particular
consideration is given to those features of the test system which might affect the
acoustic performance, such as reverberation, the presence of gas bubbles in the
sediment, or a suspension of particles above it. Sound speed and attenuation were
identified as being critical parameters, requiring particular attention. Hence, these
were investigated separately for each component of the acoustic path.
Second, there is the design and production of a transducer system. It was the intention
that this would be suitable for an investigation into the non-invasive acoustic
detection of buried objects. A focused reflector is considered to be the most costeffective
way of achieving a high acoustic power and narrow beamwidth. A
comparison of different reflector sizes suggested that a larger aperture would result in
less spherical aberration, thus producing a more uniform sound field. Diffraction
effects are reduced by specifying a tolerance of much less than an acoustic
wavelength over the reflector surface. The free-field performance of the transducers
was found to be in agreement with the model prediction. Several parameters have
been determined in this report that pertain to the acoustical characteristics of the water
and sediment in the laboratory tank in the 10 – 100 kHz frequency range.
Third, there is the design and production of an automated control system was
developed to simplify the data acquisition process. This was, primarily, a motordriven
position control system which allowed the transducers to be accurately
positioned in the two-dimensional plane above the sediment. Thus, it was possible for
the combined signal generation, data acquisition and position control process to be coordinated
from a central computer.
This series of reports is written in support of the article “The detection by sonar of
x
difficult targets (including centimetre-scale plastic objects and optical fibres) buried
in saturated sediment” by T G Leighton and R C P Evans, written for a Special Issue
of Applied Acoustics which contains articles on the topic of the detection of objects
buried in marine sediment. Further support material can be found at
http://www.isvr.soton.ac.uk/FDAG/uaua/target_in_sand.HTM.

PDF Pub9297.pdf - Version of Record
Download (848kB)

More information

Published date: April 2007

Identifiers

Local EPrints ID: 46559
URI: http://eprints.soton.ac.uk/id/eprint/46559
PURE UUID: 9c532855-ee0e-4327-8b9f-2a1f73b3c9c4
ORCID for T.G. Leighton: ORCID iD orcid.org/0000-0002-1649-8750

Catalogue record

Date deposited: 12 Jul 2007
Last modified: 17 Jul 2017 15:06

Export record

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×