On a spatial smoothing technique for multiple source location
S. S. Reddi · IEEE Transactions on Acoustics Speech and Signal Processing · 1987
This correspondence presents an alternate proof for the spatial smoothing technique recently proposed for multiple source location. Specifically, it is proved that the number of subarrays required to ensure a nonsingular covariance matrix is m + 1 where m is the nullity of the source covariance matrix. Also, it is shown that this number can be reduced if a specific basis can be found for the null eigenspace of the covariance matrix satisfying certain properties.