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

5pUW1. Single-mode excitation in a laboratory waveguide using feedback control.

John R. Buck

Dept. of Appl. Ocean Phys. and Eng., Woods Hole Oceanogr. Inst., Woods Hole, MA 02543

Res. Lab. of Electron., MIT, 77 Massachusetts Ave., Cambridge, MA 02139-4307

Mark Johnson

James C. Preisig

Josko Catipovic

Woods Hole Oceanogr. Inst., Woods Hole, MA 02543

Previous work formulated an adaptive algorithm for exciting a single mode in a shallow-water waveguide using feedback control [Buck et al., J. Acoust. Soc. Am. 95, 2927(A) (1994)]. This paper presents results obtained using this algorithm in a laboratory waveguide experiment under a variety of conditions. Unlike previous laboratory single-mode excitation experiments [Clay and Huang, J. Acoust. Soc. Am. 67, 792--794 (1980); Gazanhes and Garnier, ibid. 69, 963--969 (1981)], our algorithm does not require a priori environmental knowledge, but only the sound-speed profile at the feedback array. The experiment results to be presented demonstrate the algorithm's convergence behavior and robustness to environmental mismatch. If time permits, present experimental results illustrating the ability of the algorithm to track time variations in the channel will also be presented. [Work supported by ONR and ARPA.]