Range-dependent matched-field source localization and tracking in shallow water on a continental slope

Abstract

This paper describes matched-field source localization and tracking of a sound source towed over a continental slope off the western coast of Vancouver Island. The data were collected using a multielement vertical line array (MEVA) as part of the PACIFIC SHELF sea trial carried out during September 1993. The MEVA is a 16-element array with sensors evenly spaced at depths between 90 and 315 m. The target was towed along a linear radial track over a steep slope out to ranges of 5.5–6 km from the array, and then along a navigational arc in water depths from 250 m at the array to 750 m. The target emitted three continuous wave tones in the band 45–72 Hz. In order to model the environment as accurately as possible, the replica fields were calculated using an adiabatic normal-mode approximation which accounted for elastic wave propagation in the bottom. In addition, a bathymetric database was compiled from various echo-soundings of the area. Using conventional linear MFP based on two-dimensional replica fields to determine ambiguity surfaces for any target radial from the array, the target was tracked in range, depth, and bearing along the entire experimental track, with Bartlett processor values as large as 0.87.