Improved rooting method for source localisation

The paper describes a new, improved version of the polynomial rooting approach to direction-of-arrival (DOA) estimation with linear equispaced arrays. It is based on FINE, one of the CLOSEST approaches to spatial-spectrum estimation, and is motivated to reduce resolution thresholds. The authors show that, with the new algorithm in comparison with established rooting algorithms, resolution can be improved without compromise to DOA estimate variance for the case of ideal array response vectors. It is also shown that, as the array response vectors depart from the ideal case, the performance of root-FINE degrades only slightly more rapidly than that of root-MUSIC at high SNR; for lower SNR, root-FINE is able to partially maintain its performance advantage over root-MUSIC for the case studied