Using emitters of opportunity to enhance track geo-registration in HF over-the-horizon radar

A skywave over-the-horizon radar (OTHR) can detect and track aircraft or surface targets at ranges of 1000 to 3000 km by reflecting high frequency (HF) signals from the ionosphere. Coordinate registration (CR) is the process of registering OTHR tracks from radar to geographic coordinates. CR is often performed by ray-tracing through a real-time ionospheric model (RTIM). Opportunistic scatterers that produce identifiable radar returns from known reference points (KRPs) may also be exploited for CR. To complement traditional passive KRP sources, this paper investigates the use of uncooperative emitters of opportunity as active KRP sources to enhance OTHR track geo-registration accuracy. A method that utilizes a HF radio broadcast signal as an active KRP source for CR is presented and analyzed using experimental data from the Australian Jindalee OTHR network (JORN).