Estimating the Shape of a Towed Array of Hydrophones Using Both Acoustic and Non-Acoustic Sensor Techniques

Abstract

A summary of some recent work investigating the shape of a towed array of hydrophones is presented. Two different approaches to the problem of estimating the hydrophone positions are discussed. The first approach uses the outputs of array shape measuring sensors, such as compasses and depth sensors, as the inputs to a Kaiman Filter which recursively estimates the array shape. The second approach uses the acoustic signal received at each hydrophone in a towed array from a narrowband far-field source of opportunity. Within this approach two separate algorithms are presented. The first algorithm is an optimisation technique where a cost function, known as sharpness, is estimated so that when the estimated positions coincide with the actual positions the sharpness attains a maximum. The other acoustic algorithm discussed uses the eigenvector corresponding to the maximum eigenvalue to estimate the relative phases of the signal at each hydrophone and subsequently its position. The performance of each technique is investigated using sea trial data collected with an experimental towed array.