ASA 124th Meeting New Orleans 1992 October

4pUW6. Selective implementation of the sector-focusing matched-field processor for improved robustness in a mismatched shallow-water environment.

H. A. Chandler

C. Feuillade

G. B. Smith

Naval Res. Lab., Stennis Space Center, MS 39529-5004

In matched-field processing (MFP) inaccurate or incomplete knowledge of the environmental and system parameters required for the propagation model (referred to as modeling ``mismatch'') can lead to degradation or loss of the signal peak, and predicted estimates of the source parameters which are at wide variance with the truth. Much recent work in MFP has been concerned with the development and investigation of algorithms which provide improved stability in the presence of environmental mismatch and other modeling errors. In this study, the performance of various implementation strategies of the sector-focusing algorithm (SF) for application to a mismatched shallow-water environment is investigated. The SNAP propagation model was used to generate the replica acoustic pressure field for the water channel with a depth variable sound-speed profile. It was also used to simulate a ``detected'' field due to an acoustic source in the presence of modal noise. These were then correlated using the algorithm for selected degrees of mismatch of the water sound-speed profile. SF allows considerable flexibility in its mode of implementation. The method under investigation here employs the use of a ``sliding'' sector that contains the replica of the search point as well as those of the surrounding points. Simulation results indicate that this SF technique is highly robust against mismatch and that the sector size, shape, and dimensionality required to give optimal performance of the algorithm, for a specific degree of mismatch, is dependent upon the location of the search point within the waveguide. Numerical studies have been performed and results will be presented. [This work was supported by the Office of Naval Research, Program Element 61153N, with technical management provided by the Naval Res. Lab., Stennis Space Center, MS.]