Optimum broadband beamforming for coherent broadband signals and interferences

The problem of optimum broadband beamforming using linear arrays is conside red with a view to avoid signal cancellation that normally results when sig nal-correlated interferences are present in the environment. The optimum ap proaches proposed here are based on a harmonic model for signals and interf erences on the one hand, and a convenient characterization of the signal-fr ee interference subspace from the observed data, on the other. The characte rization so obtained leads to a broadband generalization of results reporte d earlier in the literature for narrowband beamforming. The three beamforme rs proposed here completely eliminate signal cancellation without any adver se effects. Computer simulations are presented which validate the expected performance of the three beamformers proposed here in the presence of corre lated and uncorrelated interferences. (C) 1999 Elsevier Science B.V. All ri ghts reserved.