Resolution of coherent sources by using a fast phase shifting based null steering algorithm

Abstract

This paper proposes and investigates a fast phase shifting based null steering algorithm which requires only the theoretical minimum of M + 1 (equal to or just larger than 3 2S) array elements for resolving S coherent sources. With this algorithm, the M + 1 array elements are grouped together to form M - S + 1 identical but spatially shifted power inversion sub-arrays, each having S + 1 elements and with response zeros given by phase shifts on the unit circle so that perfect nulls are formed at S directions. By performing some simple signal preprocessing and adjusting these phase shift values one after another in a time-multiplexed manner to minimize the average output power from all the sub-arrays, the external sources can be rapidly tracked and resolved without using any root-finding routine. Futhermore, with only one parameter being adjusted at any instant, the new algorithm is 4 times less complex to implement than when the LMS algorithm is used directly. © 1991.