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Computation of Averaged Sound-Propagation Losses and Frequency/Space Coherence Functions in Shallow Waters

  • Robert Laval
  • Yvon Labasque
Part of the NATO Conference Series book series (NATOCS, volume 5)

Abstract

In the frequency range covered by active sonars (above 1 kHz) sound propagation in shallow waters is characterized by fast fluctuations of the propagation-loss term as a function of range, source depth, receiver depth, and frequency. These fluctuations may be interpreted as the result of interferences between a very large number of modes. A method is presented that allows the propagation losses to be decomposed into two parts:
  1. 1.

    An averaged propagation-loss term, which takes the form of a slowly-varying function of range, depth and frequency.

     
  2. 2.

    A fluctuation term, which will be assimilated to a random function and will be characterized by its coherence functions in the range, depth and frequency domains.

     

Assumingthat the wavelength is much smaller and the horizontal range much larger than the water depth, some approximations may be introduced that allow the above functions to be expressed by continuous integrals; these integrals can be solved numerically through a rather simple computer program. The method is illustrated by some applications to a number of realistic cases in order to show the relative influence of the various parameters characterizing the bottom and the sound-velocity profile.

Keywords

Propagation Loss Sound Propagation Coherence Function Source Depth Active Sonar 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Plenum Press, New York 1980

Authors and Affiliations

  • Robert Laval
    • 1
  • Yvon Labasque
    • 1
  1. 1.Société d’Etudes et Conseils AEROParisFrance

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