Direction finding for unstructured emitters in the presence of structured interferers

This paper addresses the problem of direction finding for unstructured emitters in environments that contain interference signals with exploitable properties. The CA-JML (copy aided joint maximum likelihood) algorithm, presented here, offers dramatic angle estimation improvement in environments that contain exploitable interference. The performance improvement is equivalent to the removal of the interferers from the environment. The complexity of the algorithm, however, is comparable to MUSIC. Even when structured interferers are not present, the CA-JML algorithm can reduce the angle error bias exhibited in MUSIC in challenging environments. The CA-JML algorithm also admits a simple relaxation technique as each emitter is localized, which reduces the probability of angle estimation error due to the presence of ambiguous peaks in the angle objective function.