A UNIFIED APPROACH TO COHERENT SOURCE DECORRELATION BY AUTOCORRELATION MATRIX SMOOTHING

A wide variety of techniques have been developed to deal with coherent signals at a sensor array. Many of these techniques have the structur e of a pre-processor followed by a standard adaptive beamforming or an gle of arrival estimation algorithm, The pre-processor is designed to reduce the cross-correlations between the arriving signals. A general decorrelation technique of this type called autocorrelation matrix smo othing (AMS) is described in this paper. The processing in AMS consist s of a two-dimensional linear filtering operation on the correlation m atrix of the array measurements, A number of the previously proposed d ecorrelation techniques can be interpreted as special cases of AMS, co rresponding to different choices for the mask used to filter the corre lation matrix. Although the previous methods were not originally formu lated in terms of AMS, the unified interpretation points out relations between the techniques and suggests improved techniques. This paper s ummarizes the basic properties of AMS, explains the unified interpreta tion of previous decorrelation methods, and describes some extensions for improved decorrelation.