Existing algorithms for wideband direction finding are mainly based on local approximations of the Gaussian log-likelihood around the true directions of arrival (DOAs), assuming negligible array calibration errors. Suboptimal and costly algorithms, such as classical or sequential beamforming, are required to initialize a local search that eventually furnishes DOA estimates. This multistage process may be nonrobust in the presence of even small errors in prior guesses about angles and number of

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... ources generated by inherent limitations of the preprocessing and may lead to catastrophic errors in practical applications. In this paper, a new approach to wideband direction finding is introduced and described. The proposed strategy combines a robust near-optimal data-adaptive statistic, called the weighted average of signal subspaces (WAVES), with an enhanced design of focusing matrices to ensure a statistically robust preprocessing of wideband data. The overall sensitivity of WAVES to various error sources, such as imperfect array focusing, is also reduced with respect to traditional CSSM algorithms, as demonstrated by extensive Monte Carlo simulations. Raffaele Parisi received the "Laurea" degree in electrical engineering with honors and the Ph.D. degree in information and communication engineering from the University "La Sapienza," Rome, Italy, in 1991 and 1995 respectively. In 1994 and 1999, he was a Visiting Student and a Visiting Researcher with the Department of Electrical and Computer Engineering, University of California, San Diego. Since 1996, he has been with "La Sapienza," where he is currently a Researcher with the Information and Communication (INFOCOM) Department. His research interests are in the areas of neural networks, digital signal processing, optimization theory, and array processing.