This paper discusses the maximum number of sources when their direction of arrivals (DOAs) are estimated by the method of direction estimation (MODE), and presents a modified version of MODE that can estimate more number of sources than that by the original MODE. It is well-known that M-element array can basically estimate up to (M-1) DOAs, however the application of MODE may reduce up to M/2 DOAs because of its computation procedure. We propose a novel DOA estimation method by modifying MODE to employ peak-search of the primary eigenvector beam patterns instead of the null-search in the original MODE. Performance of the proposed method is evaluated through computer simulation.

direction-of-arrival estimation; MODE; array signal processing