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Estimation of bottom geo-acoustic parameters by inversion of beam reverberation - Impact on sonar performance prediction in shallow water

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Author: Jenserud, T. · Plaisant, A. · Ainslie, M.A.
Type:article
Date:2005
Institution: TNO Defensie en Veiligheid
Source:Papadakis, J.S.Bjorno, L., Proceedings of the 1st International Conference Underwater Acoustic Measurements: Technologies & Results , 28th June - 1st July 2005, Heraklion, Crete, Greece
Identifier: 222176
Keywords: Sonar · Active low frequency sonar · Bottom parameters · Inversion · Performance prediction

Abstract

This paper presents results obtained during the EUCLID project RTP 10.16 called “RUMBLE” carried out with contribution of several European organisations: TUS in France, TNO-FEL in the Netherlands, KDA, FFI and NGU in Norway. The objective was to assess the capability of an Active Low Frequency Sonar to estimate bottom parameters in shallow water necessary to predict ALFS performance. An inversion method based on the observation of beam reverberation power decay received on a towed array was developed by TNO-FEL and applied to experimental results obtained in the Norwegian Sea. The result of the inversion was a mapping of a set of parameters: Lambert parameter, sediment sound speed, attenuation and density, describing an equivalent bottom. The paper is focussed on the benefits brought by the inversion in terms of sonar performance predictions. For this purpose, a sonar performance model developed by TUS called “VENUS” is used to predict beam reverberation. The paper describes the experiment, the inversion results compared to ground truth measurements and the performance model VENUS. Then the model predictions using firstly a standard knowledge of bottom properties coming out from existing databases and secondly the predictions using bottom parameters obtained from RUMBLE inversion are compared with measurements in order to assess the improvement due to the inversion. The improvement is quantified, depending on the a priori knowledge of the bottom topography and geo-acoustic parameters.