Detection of environmental mismatch in a shallow water waveguide

Performance of source localization, particularly using matched-field processing techniques, is very sensitive to modeling mismatch. This paper presents a novel test for detecting modeling mismatch in a bounded propagation medium, such as shallow water. The test is based on the fact that when there are no model uncertainties, the modal spectrum of the received signal is strictly limited to an a priori known set of modes. Mismatch in the modal eigenfunction of the assumed model causes the modal spectrum out of this band to be nonzero. The proposed test requires no prior knowledge about the radiating sources. The performance of the proposed test is evaluated via computer simulations of a benchmark shallow water channel. It is shown that the test is sensitive to mismatch in the channel depth and in bottom sound speeds. The ability of the test to identify array tilt mismatch is also presented. An application of the test for validation of maximum-likelihood localization results is also discussed.