Underwater source localization using unsynchronized passive acoustic arrays

Abstract

Localizing sources of underwater sound is a well studied field that is utilized by several scientific and naval communities. The scope of localization might differ dramatically, from the necessity to localize targets with a sub-meter accuracy to estimation of the position of an object on a kilometer scale. Advances in data storing capabilities during the last decade now allow multi-year deployments of autonomous passive acoustic monitoring arrays for which past-recovery time synchronization cannot be guaranteed. For localization of transient signals, like marine mammal vocalization, arrival time based localization schemes are currently the prevalent method. Applying arrival time based methods to non-synchronized multi station arrays eventually leads to large localization uncertainties. Here, we present a backpropagation based localization scheme that overcomes the necessity to synchronize between array stations for localization purposes. It utilizes waveguide dispersion measured within distributed arrays for simultaneous source localization and time synchronization. Numerical examples are presented to demonstrate that localization uncertainty significantly improves compared to arrival time based methods.