UC San Diego

Recently in the field of Ocean Acoustics there has been a movement towards the use of passive, rather than active techniques for localizing acoustic sources and extracting information about the environment. Ships, which can be tracked using the Automatic Identification System (AIS) represent an underutilized acoustic Source of Opportunity that can potentially be used to localize sources, invert for environmental parameters, and extract information about the ocean environment such as the local time dependent Green's Function. This thesis demonstrates an application of using surface ships as a source of opportunity in source localization. Previous passive source localization methods break down due to our inability to model the acoustic environment with sufficient accuracy to create reliable replica signals; this method eliminates the need to model the waveguide by using measured, rather than modeled, replica fields. The method uses AIS ship tracking data to populate a library of replica cross-correlation vectors which are then compared to the cross-correlation of received acoustic signals on two horizontally separated hydrophones in the presence of an unknown acoustic radiator. The coordinates associated with the correlation vector from the library which most closely corresponds to the measured correlation vector must be the location of the unknown acoustic radiator. The theory is described, tested using simulations, and validated with data from a field experiment