Acoustic vector-sensor processing in the presence of a reflecting boundary

We consider the passive direction-of-arrival (DOA) estimation problem using arrays of acoustic vector sensors located in a fluid at or near a reflecti ng boundary. We formulate a general measurement model applicable to any pla nar surface, derive an expression for the Cramer-Rao bound (CRB) on the azi muth and elevation of a single source, and obtain a bound on the mean-squar e angular error (MSAE). Wt? then examine two applications of great practica l interest: hull-mounted and seabed arrays. For the Former, we nse three mo dels for the bull: an ideal rigid surface for high frequency, an ideal pres sure-release surface for low frequency, and a more complex, realistic layer ed model. For the seabed scenario, we model the ocean floor as an absorptiv e liquid layer. For each application, we use the CRB, MSAE, bound, and beam patterns to quantify the advantages of using velocity and/or vector sensor s instead of pressure sensors. For the hull-mounted application, me show th at normal component velocity sensors overcome the well-known, low-frequency problem of small pressure signals without the need for an undesirable "sta nd-off" distance, For the seabed scenario, we also derive a fast wideband e stimator of the source location using a single vector sensor.