Time-varying array shape estimation by mapping acoustic field directionality

Abstract

This paper introduces a towed-array shape estimation technique that exploits the directional structure of the time-varying acoustic field. Unlike conventional array shape estimation methods that use discrete sources of opportunity, the proposed approach does not assume knowledge of the number of sources in the field or their estimated directions. Instead, the entire time-varying field directionality map is used. Additionally, maneuverability of the array is exploited to improve endfire resolution and left/right discrimination for a nominally linear array. The algorithm forms an approximate joint maximum-likelihood estimate of time-varying field directionality and array shape using an iterative Expectation-Maximization (EM) approach. Simulations are given to evaluate the array shape estimation error during a maneuver. In a simulated multi-source scenario, the proposed method is shown to be more robust than methods that rely on direction-of-arrival estimation when the full field around the array is considered.