A time-domain implementation of data-independent robust broadband beamformers with lowfilter order

Broadband data-independent beamforming designs aiming at constant beamwidth lead to superdirective beamformers for low frequencies, if the array size is small relative to the wavelengths. Constraints on delay and complexity often render beamformers with low filter order desirable. Direct control of the robustness of these beamformers is required if they are to be applied successfully in practice. Here, we present a method where beamformers with low filter order are obtained directly from solving a constrained optimization problem which guarantees a distortionless response in the desired look direction and meets the user-defined robustness constraints. The effectiveness of this method in controlling the robustness and providing good spatial selectivity is shown by design examples.