School of Electronic, Electrical and Systems Engineering

Title:	Sediment Identification for Geotechnics by Marine Acoustics (SIGMA) Sediment Identification for Geotechnics by Marine Acoustics (SIGMA) Reflection from Bottom, Echo Classification and Characterisation of Acoustical propagation (REBECCA)
Duration:	15 months from December 2009
Sponsor:	Sponsor : European Commission, MAST-II & III Programme 3 yr EU project SIGMA (MAST-III contract PL96-1111) 3 yr EU project REBECCA  (MAST-II contract MAS2-CT91-0002)
Keywords:	Sediment Identification, non-linear acoustics, parametric sonar

The aim of the SIGMA and REBECCA projects were to investigate the relations between the acoustic parameters of marine sediments (reflection coefficient, sound velocity, attenuation, dispersion, etc.) and their geophysical and geotechnical properties (sediment type, grain size distribution, cohesion, gas content, etc.).  This directly lead from the development of a parametric array in the REBECCA project.
The acoustic parameters are estimated from wide band measurements, using a steerable parametric sonar array combined with a towed array of hydrophones. This array is mounted in a tow-fish whose pitch and roll can be monitored constantly. The sonar beam can be directed at different angles to the sea bed, depending on the requirement of any specific measurement, with real time compensation for the motion of the tow-fish. Forward-scattered signals from the sea-bottom interface and sub-bottom layers are detected by the hydrophone array. In addition, a high resolution, shear wave seismic chirp source will be used. The approach is to treat the marine environment as a complex Multiple Input/Multipe Output (MIMO) system as a means of determining the sea bed characteristics.

The theoretical aspects of the project include direct and inverse techniques for estimating geotechnical parameters, including the adaptation of a Maximum Likelihood Estimator (MLE). Another feature of the project is to carry out modelling experiments in small tanks to validate the results obtained during sea trials. Ground truth information will be obtained by conventional sea bed equipment, such as corers and improved geophysical and geotechnical module. The final task of the project is to compile a Geographical Information System (GIS). 

 

 

SIGMA
Vrije Universiteit, Brussels (Belgium) –coordinator
LU Loughborough University (UK)
CPE-Lyon (France)
CNRS/LMA (France)
Technical University of Denmark (Denmark)
Foundation of Research and Technology (Greece)
GEODIA (France)
IFREMER (France)

REBECCA
ICPI Lyon LASSO (France) - coordinator
CNRS/LMA (France)
IFREMER (France)
GEODIA (France)
Technical University of Denmark (Denmark)
Foundation of Research and Technology (Greece)
LU Loughborough University (UK)

 

P.A.Lepper & B. Woodward
''The feasibility of remotely sensing marine sediments using a parametric array'', , International Journal Society of Underwater Technology,Vol. 28, No.0, 2008.

P.A.Lepper & B. Woodward
“Real-time correction of transmission platform instabilities using a parametric array”
28th Scandinavian Symposium on physical acoustics, Ustaoset, Norway, 23-26 January 2005.

Woodward B., Lepper P. A., Vyas A. L., Balaji-Raj V. S., Taroudakis M. I. and Papadakis P. J.
“Acoustic Characterisation of Undersea Sediments To Initiate Commercial Applications (ACUSTICA); “
Proceedings of the 4th European Conference on Underwater Acoustics, 21-25 September 1998, Rome, Italy, 1998.

Cook J. C., Goodson A. D., Lepper P. A. and Woodward B.
“The design and evaluation of a phase steered parametric sonar system intended for sediment characterisation;”
Journal of the Society for Underwater Technology, Vol. 22, No 2, Winter 1996-1997, pp. 43-54; ISSN 0141 0814, 1997.

Lepper P. A. and Woodward B.
“Technique for achieving dynamic stabilisation of a sonar array platform;”
Proceedings Acoustics Society India Silver Jubilee National Symposium on Acoustics(NSA-95), 21-23 December 1995, New Delhi, India; in journal of the Acoustical Society of India, Vol. XXIII, No 4, pp. 181-186, 1995.

Woodward B., Cook J. C., Goodson A. D. and Lepper P. A.
“The REBECCA project: Acoustical remote sensing with a parametric sonar; “
Proceedings of the 2nd MAST Days and EUROMAR Market, 7-10 November 1995, Sorrento, Italy, 1995.

Cook J. C., Goodson A. D., Lepper P. A. and Woodward B.
“The Loughborough University parametric sonar system; “
Proceedings of the 1st European Workshop on Parametric Arrays, April 1995, C.P.E Lyon, Lyon, France, pp. 35-38, 1995.

Woodward B., Cook J. C., Goodson A. D. and Lepper P. 
“A phase steered  parametric array for sub-bottom profiling;”
Proceedings of the 6th International Conference on Electronic Engineering in Oceanography, Cambridge, UK, 19-21 July 1994, IEE Conference Publication No 394, pp. 77-82, 1994.

Woodward B., Goodson A. D., Cook J. C. and Lepper P. A.
“Sea bed characteristics using non-linear acoustics; “
Proc. 2nd European Conference on Underwater Acoustics, Copenhagen, Denmark, 4-8 July 1994, Edited by Bjorno L, Elsevier Science Publishers BV, ISBN 92-826-8000-2, ISSN 1018-5593, pp. 875-880, 1994.

Woodward B, Goodson AD, Cook JC and Lepper PA.

(1994b). Sea-bed characteristics using non-linear acoustics. Proc. 2nd European Conference on Underwater Acoustics, Copenhagen, Denmark, 875–880.