Joint ionospheric and target state estimation for multipath OTHR track fusion

Over-the-horizon Radar (OTHR) uses the ionosphere as a propagation medium to detect targets beyond the line-of-sight horizon. The. layered structure of the ionosphere can support several signal propagation paths between the radar site and detected targets, often giving rise to multiple radar tracks for a single target. A multi-hypothesis multipath track fusion (MPTF) algorithm for OTHR has been developed and reported in earlier publications. In this paper, the MPTF formalism is developed from first principles to explicitly explore sources of track dependence which arise in OTHR track fusion. lit particular, a solution is proposed which accounts for track-to-track dependencies arising from common target and ionospheric dynamic processes. The algorithm is applied to the simplest nontrivial case, where the ionosphere is modelled as two spherically-symmetric reflecting layers, and two radar tracks are observed.