Matrix spatial prefiltering approach for direction-of-arrival estimation

An approach to direction-of-arrival (DOA) estimation for multiple narrowband farfield signals is proposed. The technique uses a novel spatial prefiltering approach. Specifically, a matrix filter is designed to spatially filter the incoming data snapshots. The unwanted components within the stopband sectors are attenuated and the desired components in the angular sector of interest pass with minimal distortion. The matrix filter spatially filters the element-space data and generates also an element-space output, which makes it very useful by passing sensor data through a spatial prefilter prior to applying many other array processors to attenuate interferences and improve system performance. Several examples of DOA estimation problem are present to illustrate the performance of the proposed spatial prefiltering approach. Results of simulation and real data show that the prefilter can efficiently attenuate the spatial interferences, significantly improved the estimation and resolution capability of DOA estimators at low signal-to-noise ratios. In addition, the use of spatial prefilter makes it possible to estimate DOAs for multiple sources more than the number of the elements of an array.