RANGE-DEPENDENT REVERBERATION AND TARGET ECHO CALCULATIONS USING THEDRDC ATLANTIC CLUTTER MODEL

摘要

A shallow water reverberation model based on normal modes has been developed and refined at DRDC Atlantic over the years [Ellis, 1985; 1995]. Originally, the model handled range independent boundary reverberation in monostatic or bistatic geometries, including source and receiver beam patterns for comparison with measured data, and was later extended to handle target echo. The formulation was extended to range-dependent environments using adiabatic normal modes [Ellis et al., 2008]. The computations presented at that time used a Matlab/Fortran hybrid model with modes evaluated on a rectangular grid. While the scattering strength and echo at any point on the grid could be arbitrary, a constant water depth was still required. In 2009 a range-dependent Matlab/Fortran code was developed for monostatic reverberation calculations along a single radial [Kwan and Ellis, 2010]. In 2010, a model (implemented in Fortran 95) was developed to handle both sloping bathymetry, and towed array beam patterns in bistatic geometry on a 2-D grid. The model is computationally efficient and its capabilities are evolving. Work is in progress to implement it into jAMI [Brooke et al., 2010], as well as the DRDC Atlantic System Test Bed and Pleiades System which is sometimes used by the Canadian Forces. Model-data comparisons of towed array clutter data obtained on the Malta Plateau are underway, as well as comparisons with several range-dependent problems from the ONR Reverberation Modeling Workshop [Thorsos and Perkins, 2008], and the UK Institute of Acoustics workshop on Validation of Sonar Performance Assessment Tools [Zampoli et al., 2010].