DECORRELATION OF BROAD-BAND SIGNALS BY TOEPLITZ-BLOCK-TOEPLITZ STRUCTURING

We propose F-norm of the cross-correlation part of the array covarianc e matrix as a measure of correlation between the impinging signals and study the performance of different decorrelation methods in the broad band case using this measure. We first show that dimensionality of the composite signal subspace, defined as the number of significant eigen vectors of the source sample covariance matrix, collapses in the prese nce of multipath and the spatial smoothing recovers this dimensionalit y. Using an upper bound on the proposed measure, we then study the dec orrelation of the broadband signals with spatial smoothing and the eff ect of spacing and directions of the sources on the rate of decorrelat ion with progressive smoothing. Next, we introduce a weighted smoothin g method based on Toeplitz-block-Toeplitz (TBT) structuring of the dat a covariance matrix which decorrelates the signals much faster than th e spatial smoothing. Computer simulations are included to demonstrate the performance of the two methods.