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| Le Gall, Yves; Pacault, Anne; Saint-laurent, Xavier; Viaene, Jean-michel; Mosca, Frédéric; Greninguey, Gilles; Vial, Marcel; Aissa, Jean Claude. |
| Acoustical techniques for ultra-deep sub-bottom exploration are still little investigated. IXSEA and IFREMER have launched in 2006 the development of a new deep-sea low-frequency sub-bottom profiler, working up to 6000 meters depth. Based on the Janus-Helmholtz broadband technology, two acoustic sources have been modelled, achieved and in-tank and at-sea measured : a single transducer working in the [1.8, 6.2 kHz] frequency band, and a three-transducer array operating in the [2, 8 kHz] frequency band. In both cases, vertical resolution is better that 20 cm. Comparison between finite element modelling and in-tank measurements is presented, together with the specific constraints linked to very-deep water and AUV mounting. Power electronics and impedance... |
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| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/00127/23836/21764.pdf |
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| Theuillon, Gwladys; Stephan, Yann; Pacault, Anne. |
| Subbottom profilers are commonly used to explore the first sediment layers below the seafloor. Recent narrowbeam profilers achieve improved performances in terms of signal-to-noise ratio (SNR) and resolution. Thus, the potential of these systems for near real-time geoacoustic characterization of sediments is high and is worth being specifically explored. This paper presents several methods to estimate geoacoustic parameters such as the absorption, the reflectivity, and the impedance contrast. These procedures are tested against real data collected with the SBP 120 subbottom profiler during the CALIbration MEthodology for Recognition of the Ocean bottom (CALIMERO) experiment. It is shown that the absorption and impedance contrast estimates are fully... |
| Tipo: Text |
Palavras-chave: Subbottom profiler; Spectral ratio; Impedance contrast; Geoacoustic inversion; Eckart's model; Absorption. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-6159.pdf |
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