2023_programme: Source range estimation using the array invariant in a fluctuating shallow waters environment.

• Session: 11. Prospective underwater acoustics : at-sea experiments
  Organiser(s): Jean-Pierre Sessarego, Dominique Fattaccioli and Gaultier Real
• Lecture: Source range estimation using the array invariant in a fluctuating shallow waters environment. [invited]
  Paper ID: 2014
  Author(s): Beaumont Guillaume, Real Gaultier, Allouche Jean-Marc
  Presenter: Beaumont Guillame
  Abstract: Recent works in the literature demonstrated the possibility to estimate the source-receiver range using the waveguide and array invariants. This method approximates the ellipsoid in the angle-delay space using a least square approach to retrieve the array invariant. An approximation is then made to estimate the source-receiver distance, considering a perfect waveguide propagation. \nThe presence of internal waves and other perturbations in a stratified medium can induce variations of the local celerity and impact a propagated sound wave significantly. Focusing on the case of internal waves, the impact on a propagated signal has been quantified in terms of statistics on phase and amplitude perturbation by the work of Dahsen et al . In particular, internal waves are known to impact directly the travel time and angle of arrival of acoustic paths. \nUsing the quantities defined in this work, we evaluate the impact of the fluctuations on the shape of the ellipsoid in the angle-delay space, hence the impact on the range estimation least square method defined by Song et al.\nThis impact is observed by processing the data from the 2016 ALMA campaign. We here focus on the 1-14 kHz LFM sequence emitted in a shallow waters environment. Comparing non-fluctuating and fluctuating subsets of data, results show the corruption of such fluctuations on the shape of the ellipsoid and the quality of range estimation.
• Corresponding author: Dr Guillaume Beaumont
  Affiliation: DGA Techniques Navales
  Country: France
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