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In 2005, artificial targets were placed on a flat sandy seabed, with
a low rocky reef at a depth of 9-10m in a sheltered location
within Plymouth Sound (the area already has an artificial target, a
5m long boat, in place). The targets were surveyed using a Scout ultra
short base line (USBL) acoustic positioning system with assistance from
Sonardyne Ltd.
Sonardyne website.
The targets comprised a range of
object shapes and material types
that could be found on marine archaeological sites within
aggregate extraction areas, including modern intrusive material.
The empirical sidescan experiment conducted jointly by the Universities
of St Andrews and Ulster in 2002 (Quinn et al 2005) has provided
a useful methodological parallel.
For further details of the types of targets being used, please see
the project design document in the library section of this site:
Library.
Surveys were then undertaken from the survey vessel Xplorer, and utilised a
dual head Reson SeaBat 8125 and Submetrix 2000 multibeam systems,
as well as a Klein 3000 sidescan.
The use of a control site in this way is allowing evaluation of the effectiveness
of multibeam and sidescan sonar systems in data gathering, measured against industry standard
SBL acoustic methods, while
the identification of target signatures provided by an array of geophysical
equipment should help the project develop mathematical algorithms and documentation to aid interpretation
of remote sensing data in the future.
Above right: Map of Plymouth Sound, showing areas surveyed
in advance of this project (coloured).
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You can evaluate the efficacy of the two principle techniques
employed - sidescan and multibeam - for yourself, in our interactive
feature based on the survey results:
Interactive feature showing 2005 results.
Back to results/other sites.
References
Quinn R., Dean, M., Lawrence, M., Liscoe,S., and Bolan,D., 2005,
Backscatter responses and resolution considerations in archaeological side-scan
sonar surveys: a control experiment. Journal of Archaeological Science 32 pp. 1252-1264
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Plymouth Sound - overview
