Geolocation of HF skywave radar signals using multipath in an unknown ionosphere

A method is proposed to jointly estimate the ground position of a point source, which transmits or scatters a known HF radar signal, and the virtual heights of reflection in an unknown ionosphere using the group-range and cone angle-of-arrival measured for each propagation mode by a multi-channel receive system connected to a uniform linear array (ULA) of antennas. Specifically, the method exploits multipath propagation of HF signals in the ionosphere and the geometrical relationships that constrain such propagation to derive a new estimator for a coordinate registration (CR) problem that inherently produces an ambiguous solution if the modes are considered individually. Field data gathered by the Australian Jindalee OTH radar in a controlled experiment with known truth information is used to validate the method.