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

## 3pUW8. Shallow water single mode excitation using feedback control.

**John R. Buck
**

**
Denis Peregrym
**

**
**
*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
*

*
*
**James C. Preisig
**

**
Josko Catipovic
**

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

*
*
This work presents an adaptive algorithm for exciting a single mode in the
shallow water acoustic waveguide. Previous efforts have focused on laboratory
waveguides using pre-computed weights for the source array based on precise
prior knowledge of the channel [Clay and Huang, J. Acoust. Soc. Am. 67,
792--794 (1980), Gazanhes and Garnier, J. Acoust. Soc. Am. 69, 963--969
(1981)]. In contrast to these open-loop systems, the algorithm presented here
uses a reference receiver array to implement a closed-loop feedback control
system. The channel is characterized through an effective coupling matrix
relating the source weights to the coefficients of the excited modes. The
algorithm iterates between estimating the coupling matrix from the reference
observations, and determining the source array weights from the estimated
coupling matrix. Results from detailed simulations using actual sound-speed and
bottom parameters indicate this approach allows the algorithm to adapt and
compensate for environmental mismatch and some time-dependent fluctuations.