2019_programme: ALMA 2015 : STUDY AND MODELING OF THE IMPULSE RESPONSE VERTICAL DE-COHERENCE OF A FLUCTUATING SHALLOW CHANNEL

• Session: 10. Design of new experimental facilities to address future problems in underwater acoustics
  Organiser(s): Sessarego Jean-Pierre, Fattaccioli Dominique, Real Gaultier
• Lecture: ALMA 2015 : STUDY AND MODELING OF THE IMPULSE RESPONSE VERTICAL DE-COHERENCE OF A FLUCTUATING SHALLOW CHANNEL
  Paper ID: 869
  Author(s): Bennaceur Iannis, Cristol Xavier, Chalindar Bruno, Real Gaultier, Fattaccioli Dominique
  Presenter: Bennaceur Iannis
  Presentation type: oral
  Abstract: Before reception by a sonar array, acoustic signals of interest are strongly altered during propagation through the unstationary inhomogenous random sea. Some configurations, like shallow waters, are particularly impacted by strong stochastic fluctuations of the sea features and much work is still needed to understand, model and mitigate the effects of random acoustic propagation on the sonar performance. \nAcoustic propagation in shallow water is investigated using signals collected by the “ALMA” (Acoustic Laboratory for Marine Applications) system deployed in 2015 by DGA Naval Systems, in the Mediterranean Sea. The 2015 instrument configuration combined an acoustic source transmitting different types of wide- and narrow-band pulses over the 2 to 11 kHz band, and a 10 meter high receiving vertical array of 64 hydrophones. The main topic of this article is the experimental study of the vertical loss of coherence of the received signals, which would have an impact on sonar performance. The first step of the work was to evaluate the impulse response and a vertical coherence characteristic length using the pulses propagated through the stochastic fluctuating channel in a relatively calm-sea configuration. Then, the observed impulse responses and the coherence scales are simulated with the in-house stochastic numeric tool NARCISSUS and compared to the experimental measurements. \n
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• Corresponding author: Dr Bennaceur Iannis
  Affiliation: THALES Defense Mission Systems FRANCE
  Country: France
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