Direction Finding of Multipath Signals

Multipath propagation is a common cause of anomalous azimuth estimates in direction finding of radio signals. Anomalous estimates often occur at the same level of multipath components coming from close directions, if the initial phase difference between them is near to 180°±20°. With strongly differing arrival directions of multipath components, the unreliable azimuth estimates are formed by single-signal direction finding algorithms. The paper considered the algorithms for direction finding of multipath signals at close and strongly divergent directions of arrival of multipath components and the algorithm for censoring the anomalous azimuth estimates formed by the traditional algorithm of phase direction finding. Estimation of close arrival directions of multipath components was based on evaluation of path delays using ESPRIT in the frequency domain. The conventional algorithms for direction finding of multiple signals are applicable for strongly different directions of arrival of multipath components. The processing of real signals records and databases by the proposed algorithms indicated the absence of anomalous azimuth estimates.