### 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.]