ASA 127th Meeting M.I.T. 1994 June 6-10

3aSAb8. Phase space footprints of truncated periodicity: Frequency domain wave-oriented data processing.

L. B. Felsen

L. Carin

T.-T. Hsu

D. Kralj

Dept. of Electrical Eng., Polytechnic Univ., 6 MetroTech Ctr., Brooklyn, NY 11201

An asymptotic theory for frequency and time domain acoustic scattering due to truncated periodicity modeled by filamentary scatterers has been presented recently [L. B. Felsen and L. Carin, J. Acoust. Soc. Am. 95, 638--649 (1994)]. The solution is parametrized in ray-acoustic forms which contrast individual scattering events with collectively restructured events over the equivalent Bragg-modulated aperture distribution covering the extent of the array; the resulting scattered fields involve truncated Bragg beams and Bragg-modulated edge diffractions. Wave-oriented processing is now applied to the frequency domain scattering data to extract the ray-acoustic phenomenologies. The setting is the (x,z,k[sub x],k[sub z])[sub (omega)] phase space where k[sub x] and k[sub z] are the spatial spectral wave numbers corresponding to the x and z coordinates, with the frequency (omega) as a parameter. The phase space footprints are extracted by windowed and global transforms that yield various local and global distributions displayed by alternative visualizations. Of special interest are the footprints pertaining to the structurally dispersive Bragg modes. Discussion includes linkage of phase space footprints with the scattering configuration. [Work supported by AFOSR.]