Pruned multi-angle resolution fast beamforming

Delay-and-sum (DS) beamforming is one of the basic beamforming methods, and it is effective for both narrowband and wideband sources. However, DS beamforming exhibits high computational complexity. Recently, a fast multistage approximation of DS beamforming was introduced (Oh, S.-M. and McClellan, J.H., Proc. ICASSP-2002, p.2937-40, 2002). In order to improve the computational efficiency of the fast beamformer further, we have integrated a detector into the intermediate stages of the fast algorithm. This detector can save computations by stopping further processing to resolve benign angular sectors that do not contain a coherent source. The joint fast detector/beamformer was tested using various wideband signals such as spread spectrum signals used in wireless communications. This technique should provide a useful direction finding solution in wireless communications and target localization applications. In addition, the fast algorithm can find initial values for high resolution direction-of-arrivals estimators such as coherent signal-subspace methods.