Improvements to the Acoustic Multistream Propagation Program.
ARMY RESEARCH LAB WHITE SANDS MISSILE RANGE NM
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The Acoustic Multistream Propagation Program AMPP makes use of repeated calls to the Fast Field Program FFP to calculate the sound pressure level from a combination of sources and scatterers in a horizontally stratified atmosphere. Although FFP treats only isotropic sources, AMPP has been used to produce dipole type fields by coherent summation of the sound pressures of appropriately positioned sources and scatterers. In addition, scatterers can be positioned to scatter the sound pressure of the incoming field into a shadow zone, which may be useful for non-line-of-sight acoustic detection problems. The basic characteristics of AMPP have been described elsewhere. This report discusses modifications made to AMPP since April 1993, in support of, and including, the coherent summation subroutine. An example is given on how to use AMPP to model anisotropic scatterers, and graphical output from this example is included. Finally, some remarks are included regarding the limitations of AMPP.