Hybrid phase-shift/time-delay digital beamforming

Abstract

Digital phase-shift beamforming of narrow-band signals from uniform colinear hydrophone arrays may be accomplished by computationally efficient algorithms which exploit the functional regularity of the required phase-shift operations. However, phase-shift beamforming is a valid approximation to delay-and-sum steering over only a limited bandwidth whose value depends on array aperture and steering angle. This paper describes a multiple-beam digital beamforming structure which is a phase-shift/time-delay hybrid and which an be designed for operating bandwidths in excess of the phase-shift limit. Much of the computational efficiency of colinear array phase-shift beamforming is retained in this approach, and it can offer substantial advantage over the alternative of delay steering by digital interpolation. This will be demonstrated by examples.