Application of the fast Fourier transform to broadband beamforming

Abstract

The processing of broadband signals using an array of sensors is normally carried out in a time domain using a tapped delay line filter or in a frequency domain where each frequency channel is weighed by complex weights and no tapped delay line filter is required. The time domain implementation of the broadband structure is important in the area of communication where the frequency domain implementation may not be suitable due to its associated delay. This paper derives relationships between the weights, the array correlation matrices, and the constraints on the weights of the two structures to produce identical results. These relationships are then used to update the weights of the tapped delay line filter structure using narrow-band techniques. The method has potential for computational saving to estimate weights of the broadband structure, for a large bandwidth signal requiring a long tapped delay line filter.