A bi-axial velocity-sensor colocated with a pressure-sensor—Direction-finding imprecision due to the incident source’s directional spreading

This paper investigates the direction-finding precision, when the incident source suffers spatial/direction spreading, obtainable from a triad consisting of a biaxial velocity-sensor colocated with a pressure-sensor. Such a planar array has a low physical profile, thus easing affixation onto a mobile platform. The three component-sensors' spatial colocation mathematically decouples the incident wavefield's time-frequency dimensions from the polar-azimuthal directional dimensions. The statistical measure of direction-finding precision here is the Cramer-Rao lower bound of any unbiased estimate's variance.