High resolution coherent source location using transmit/receive arrays

In this paper we present a general approach to super resolution imaging of point sources using active arrays of transmit/receive elements. The usual techniques of high resolution imaging using single transmitters and passive receive arrays fail in the presence of sets of coherent point sources, which often arise due to coherent multipath. However, data obtained from transmit/receive arrays may be arranged into matrices to which eigenspace direction of arrival estimation may be successfully applied, even in the presence of coherent sources. Each such matrix may be thought of as corresponding to a different transmit/receive array; this may be either the actual transmit/receive array or a virtual transmit/receive array whose effect is synthesized. This approach provides great flexibility, since a large number of different synthetic or virtual arrays may be available for a given transmit/receive array, and each can provide a different tradeoff between the total number of resolvable targets and the largest number of mutually coherent targets which can be resolved.