Azimuth-elevation direction finding using one four-component acoustic vector-sensor spread spatially as a parallelogram array

An acoustic vector-sensor (a.k.a. a vector hydrophone) consists of three uni-axial velocity-sensors (which are oriented perpendicularly with regard to each other) and one pressure-sensor. Song and Wong have demonstrated how to space these four component-sensors apart in three-dimensional space, in order to extend the overall spatial aperture spanned by them, while improving the accuracy in estimating the azimuth-elevation direction-of-arrival of an acoustic emitter incident from the far field. This paper will focus on a special spatial geometry—where the four component-sensors occupy the four corners of a parallelogram in three-dimensional space.