Underwater Acoustic Source Positioning by Isotropic and Vector Hydrophone Combination

Abstract

Acoustic vector hydrophones are well-known for their ability in estimating the direction of arrival (DOA) of incoming signals. Moreover, despite its directivity, a vector hydrophone is capable of providing information about the received signal strength (RSS), just as an isotropic hydrophone. In this paper, a heterogeneous positioning system consisting of an isotropic and a vector hydrophone is considered and, then, a novel positioning algorithm for localization of an acoustic underwater source located in the near field is developed. In this context, a new efficient algorithm is proposed for DOA estimation by performing the space-frequency processing on the vector hydrophone's data. Then, the range estimation problem is formulated in terms of the Lambert W function by considering the estimated DOA and employing the RSS measurements. In the case where the source is located nearer to the vector hydrophone than to the isotropic hydrophone, a solution for the source range is derived. Furthermore, the estimated range is significantly improved through a novel procedure which eliminates the power of background noise in the measured RSS. Moreover, the effects of shadowing, colored noise, multipath propagation, and mismatch in the channel parameters on the proposed method are investigated. Simulation results indicate reasonable improvement in terms of DOA accuracy compared to the prototype eigenstructure-based algorithm.