Airborne Very Long Baseline Interferometry and Geolocation

A method is presented of performing geolocation of fixed emitters from a single, airborne platform using a two-element, very long baseline interferometer (VLBI) from 10 to 100 feet in length. The interferometer baseline is precisely tracked through a differential GPS system using auxiliary antennas placed in close proximity to the VLBI pair. A lever arm correction is applied to arrive at the VLBI baseline from the GPS measurements. A batch least squares processing algorithm is presented that operates on the interferometric phase measurements directly and resolves the associated ambiguities through global search strategies. A method of eliminating receiver phase bias by performing a difference operation is shown. Simulation results and Cramer-Rao lower bounds are also presented