Experimental study of superdirective frequencyinvariant beamforming for a circular hydrophone array

This paper first presents a superdirective frequency-invariant beamforming method for circular sensor arrays. The weighting vector of this method is in close-form, which is derived using the criterion of minimizing the mean square error between the desired and synthesized beampatterns. A detailed experimental study of this superdirective frequency-invariant beamforming method is then followed, which is used to further demonstrate its performance. In the experiment, the superdirective frequency-invariant broadband beamformers with a specific response are designed so that they can be applied to effectively suppress the ambient noise. The experimental data are processed in the time domain in which finite impulse response filters are designed according the obtained superdirective frequency-invariant broadband beamformers. The results show that this superdirective frequency-invariant beamforming method provides good signal-to-noise ratio enhancement.