ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

5aUW15. Coregistration of received signals with bathymetry using artist.

Vincent H. Lupien

J. Robert Fricke

Dept. of Ocean Eng., MIT, Rm. 5-435, 77 Massachusetts Ave., Cambridge, MA 02139

As part of the ARSRP, a software package called Acoustical Ray-Tracing Insonification Software (artist) was developed which performs the coregistration of received signals to areas of the seafloor for direct paths. The transmitting and receiving array beampatterns are projected onto the actual seafloor by ray-tracing to yield two insonification patterns. The (x,y) loci of ray contacts with the seafloor are then triangulated and shadow-zone processed so that the interior of each triangle is inside the illuminated region. Using a bivariate interpolator over each triangle of the insonification patterns, an intersection pattern is generated on a rectangular grid, yielding among other parameters: two-way travel times, TL, beampattern values, and grazing angles. Only the points which lie in the illuminated zones of both the receiver and transmitter are kept. By using another bivariate interpolator over each patch of the intersection pattern, pairs of time contours are generated and for each patch intersected by a contour; the fractional area lying inside the time window is calculated. The final step in the coregistration is to select only those patches which are most loudly insonified for each time window. The patches do not have to be adjacent and the amplitude criteria are user-specified. [Work supported by ONR.]