-The subject of the paper is the determination of the number of wideband signals impinging on a passive sensor array in the form of multiple groups (clusters), and the estimation of their directions of arrival. The idea of preprocessing by a set of orthogonal beamformers for dimensionality reduction, is used to simplify wideband processing. Demonstration of the effectiveness of this approach is carried out with the use of discrete prolate spheroidal sequences (DPSS’s) as the beamformers for linear uniform arrays. A weighting gain as an indicator of the improvement in the signal-to-noise ratio (SNR) due to such preprocessing is introduced. Two versions of an algorithm that combines preprocessing/prefiltering and the coherent signal subspace (CSS) method in the frequency domain are developed and comparative performance evaluations are carried out. Finally, the relative effects of beamspace prefiltering on optimum and suboptimum estimators is explored.
Bibliographical noteFunding Information:
Manuscript received August 7, 1990; revised March 1, 1991. This work was supported in part by SDIO/IST managed by the Office of Naval Research under Grant N00014-86-K-0410, and in part by the National Science Foun- dation under Grant MIP-8813204. The authors are with the Department of Electrical Engineering, University of Minnesota, Minneapolis, MN 55455. IEEE Log Number 9102021.