Hull-mounted acoustic vector-sensor processing

We consider the direction-of-arrival (DOA) estimation problem using arrays of acoustic vector-sensors located at a solid-liquid boundary. We formulate a measurement model and derive an expression for the Cramer-Rao bound (CRB) of a single source. The CRB is used to analyse the case of rigid and pressure-release surfaces in detail and comparison is made with pressure-sensor arrays. In particular, we show that a pressure-sensor array needs to be somewhat less than a quarter wavelength from a pressure-release surface to have comparable performance to an array of velocity sensors mounted at the surface.