Matched-beam processing: Range tracking with vertical arrays in mismatched environments

Abstract

This paper addresses the problem of range tracking using one or more vertical arrays in certain mismatched shallow-water environments. The objective is to obtain continuous tracking of a target thereby allowing the target to be distinguished from false alarms. It is shown that bottom mismatch can cause large range errors at discrete source ranges as observed in previous experiments. Also, significant range errors (offsets) can result from unknown array tilt. Discrete range errors impede the ability to detect a target by integrating along the target track (track-before-detect) or by a probability based target detection and tracking algorithm. Large range errors impede the ability to localize and track the target from multiple vertical arrays. These problems are addressed using matched-beam processing whereby certain bottom mismatch is minimized by a beam filter and unknown array tilt is estimated by matching the measured beam pattern against the calculated one. Beam filtering and beam matching are simple and convenient methods to implement in practical systems. Comments are also given on other applications using beam domain processing.