1aAO9. Multimodal dispersion identification.

Session: Monday Morning, May 13

Time: 10:20

Author: James Poplawski
Author: Ted Birdsall
Location: Dept. of Elec. Eng. and Comput. Sci., Univ. of Michigan, 1301 Beal, Ann Arbor, MI 48109


Geometric dispersion in the deep ocean sound channel causes wideband modal arrivals to be spread significantly in time at long ranges. This results in a low modal peak signal-to-noise ratio and interference due to multiple overlapping arrivals. These effects make the identification of individual modal arrivals difficult without the use of a vertical receiving array. The time compression of modal arrivals using phase-only filters is examined as a method for locating and identifying arrivals from a reception at a single depth. A search display, dubbed the dispersion diagnostic display, has proved its worth in computer simulations using a 60 mode range invariant model of SLICE89 propagation. The DD display simultaneously shows a raylike (no dispersion) structure and a patterned modal structure with strongly dispersed early arrivals and lightly dispersed terminal arrivals. [Work supported by ATOC.]

from ASA 131st Meeting, Indianapolis, May 1996