Focussed partially adaptive broadband beamforming via spatial resampling

Summary form only given. A focusing technique that can reduce each wideband interferer in multigroup scenarios to essentially a rank-one representation without preliminary estimates of the group locations has been developed. The method is based on adjusting the spatial sampling rate or spatially resampling the array outputs, as a function of temporal frequency. Resampling has the effect of rescaling the spatial frequency axis at each temporal frequency. For proper focusing, the rescaling factors are selected so that the spatial frequency of each wideband arrival in the resampled sequences is the same for all temporal frequencies in the receiver band. A linear shift-variant transformation that can perform the required resampling operation has been designed. The array gain of the focused minimum variance distortionless response (MVDR) beamformer has been compared with its fully adaptive counterpart in some common broadband interference-dominated scenarios