The effects of preprocessing on direction of arrival estimation

Numerous authors have advocated the use of preprocessing (PP) in high-resolution direction finding algorithms. The optimal PP matrix is identified, in the sense that the accuracy of the direction of arrival estimates are unaffected by the preprocessing step. The authors derive the preprocessing matrices which provide minimum variance estimates for a number of models and algorithms. They then study the Cramer-Rao bound (CRB) for Gaussian signals, the CRB for deterministic signals, and the asymptotic variance of the multiple signal classification (MUSIC) estimator for the preprocessed data. The effect of array manifold errors on direction estimation accuracy is also examined.<>