Broadband signal simulation in shallow water
Today's minimum requirements for ocean acoustic models are to be able to simulate broadband signal transmissions in 2D varying environments with an acceptable computational effort. Standardapproaches comprise ray, normal mode and parabolic equation techniques. In this report we comparethe performance of four broadband models (GRAB, PROSIM, C-SNAP and RAM) on a set of shallowwatertest environments with propagation out to 10 km and a maximum signal bandwidth of 10-1000 Hz. It is shown that a computationally efficient modal approach as implemented in the PROSIM model is much faster than standard, less optimized models such as C-SNAP and RAM. However, thehandling of range dependency in the adiabatic approximation is not always sufficiently accurate, and itis suggested that a mode coupling approach be adopted in PROSIM. Moreover, the interpolation ofmodal properties in range could lead to a further significant speed-up of mode calculations in range-dependent environments. It is concluded that coupled modes with wavenumber interpolation in both frequency and range remain the most promising wave modeling approach for broadband signal simulations in range-dependent shallow water environments. At higher frequencies (> 1 kHz) there is currently no alternative to rays as a practical signal simulation tool.
Jensen, Finn B.;
Ferla, Carlo M.;
Nielsen, Peter L.;
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Ferla, Carlo M.; Jensen, Finn B. (NATO. SACLANTCEN, 1999/08)A set of AESS propagation-loss predictions has been generated for typical operational scenarios in both deep and shallow water, for two sonar frequencies (500 and 3500 Hz) and for several source-receiver combinations. ...
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