2019_programme: PROOF OF CONCEPT OF RAPID ENVIRONMENT ASSESSMENT BY DISCRETE ACOUSTIC TOMOGRAPHY

• Session: 24. Inversion methods in underwater acoustics
  Organiser(s): N/A
• Lecture: PROOF OF CONCEPT OF RAPID ENVIRONMENT ASSESSMENT BY DISCRETE ACOUSTIC TOMOGRAPHY
  Paper ID: 946
  Author(s): Chavanne Robert, Gallou Roger, Folegot Thomas, Stéphan Yann, Kinda Bazile
  Presenter: Chavanne Robert
  Presentation type: oral
  Abstract: Authors: Robert CHAVANNE (), Roger GALLOU (), Thomas FOLEGOT (), Quiet-Oceans 525 Avenue Alexis de Rochon 29280 Plouzané, France;\nYann STEPHAN (), Bazile KINDA (), Service hydrographique et océanographique de la marine (SHOM) CS 92803 29228 BREST CEDEX 2\n\nRapid Environment Assessment (REA) can be used to predict environmental parameters and estimate sonar performance. Among the parameters of importance for sonar, the bottom sediment properties strongly influence the propagation. There are different kind of interesting information on the sediment from its type (hard / soft) to accurate parameter estimation. Inversion methods based on free active acoustical emission have successfully been developed to estimate acoustic properties of the sediment. For several years, SHOM is working on similar methods for discrete REA in shallow water. In this case, both the acoustical emissions and the used devices must not be detected. Hence the proposal to use natural acoustic sources (passive REA) or signals that mimic some of those sources (discrete REA).\n\nFollowing this theoretical work, ERATO16 is a proof of concept project that aims to validate/invalidate those methods. A first campaign took place in 2016 during which a hydrophone was deployed for a whole month recording ship traffic noise. A second campaign was lead in may 2018 and June 2018. It relied on the use of two light autonomous underwater vehicles (AUV) and several buoys that enable an accurate positioning of the AUV. Both vehicles can emit different kind of emissions, record and follow some predefined pattern.\n\nThe data acquired are now processed through a dedicated platform developed by Quiet-Oceans that implements inversion methods including ship noise modeling with Quonops, active methods based on the knowledge of emissions and passive methods applying to natural signal (e.g. modulation) or ship’s passage. The final contribution will first introduce the different methods and the experiments that have been done with more details. Then, the results obtained so far will be shown and a comparison with the actual knowledge of the area will be made leading to some concluding remarks.
• Corresponding author: Dr Chavanne Robert
  Affiliation: Quiet-Oceans
  Country: France
  e-mail: