Multi-Signal Ambiguity in Direction-of-Arrival Estimation

Array ambiguities and the design of ambiguity-free arrays have been studied extensively. These studies usually focus on the case of a single signal. The analytical study of ambiguities in the multi-signal case is difficult and possibly intractable for general arrays with realistic models of the manifold. This paper uses the covariance manifold and the framework of covariance matching to perform a numerical study of this problem. We demonstrate by example the increase in the number of ambiguities as the number of signals increases. Multi-signal ambiguities are an important and often overlooked factor limiting the number of signals which can be uniquely estimated by an array.