In situ assessment of a single underwater acoustic vector sensor for direction-of-arrival estimation over multiple ranges
Abstract
Underwater acoustic vector sensors (AVSs) are widely used for direction-of-arrival (DOA) estimation in underwater surveillance and marine bioacoustics applications. Compared with conventional hydrophone arrays, a single compact AVS offers greater flexibility and simpler deployment while enabling DOA estimation using the acoustic active-intensity method (AIM). However, the in situ performance of AVSs for DOA estimation using
Aim
has been investigated only to a limited extent. To address this, we conducted field experiments using a commercial AVS deployed on the seabed off the coast of Norway. A sound projector suspended from a research vessel transmitted a 600 Hz tonal signal over ranges of 1–6 km from the AVS, providing full 360° azimuthal coverage at 1 km and single azimuth measurements at 2, 4, and 6 km. The vessel maintained its position during acoustic transmissions using a dynamic positioning system, and the DOA estimates obtained from
Aim
were compared with ground-truth bearings derived from GPS data. Results showed that
Aim
effectively estimated DOA under multipath propagation conditions, particularly at long ranges, although temporal variability in the acoustic field led to increased estimation errors. This study underscores the potential of underwater AVSs for long-range marine sound source localization and target tracking, including marine mammal monitoring.