Radio location through high resolution eigenstructure processing techniques that yield accurate multipath AOA and differential time delay estimates

An eigenstructure-based, doubly adaptive array processing algorithm is described. This algorithm was designed to resolve the differential time of arrival between a direct signal and a delayed replica that arrives via a different ray path. Simulations, using theoretical responses of a circular eight-element dipole array, demonstrates the characteristics of this doubly adaptive technique. Experiments have demonstrated robust differential time delay resolution of HF signals propagated to an array by two paths, a surface wave path and a skywave path. Differential time delays of approximately 1.9 milliseconds were observed for both pulse and phase modulated RF signals