A fast beamforming algorithm

The paper describes a new algorithm for fast beamforming (FBF) on wide-band signals. Conventional delay-sum beamforming (DSBF) is a computationally intensive operation requiring on the order of N² delay/sum operations per sample period, where N is the number of sensor elements. The FBF algorithm requires on the order of NlogN operations, which can result in considerable savings for large values of N. The algorithm defines multiple stages of processing. In the first FBF stage, DSBF is done for multiple subarrays with a limited number of beams. At each successive stage, the beams from pairs of subarrays are combined and additional beam steering directions are developed. The sidelobe level performance of FBF is found to be a function of beam spacing. The computational requirements of FBF are evaluated and compared to DSBF. The savings grow rapidly with array size, though can still be appreciable for as little as 32 elements. A simulated example of the algorithm on a wide-band signal is shown