Geolocation of Unknown Emitters Using Tdoa of Path Rays Through the Ionosphere by Multiple Coordinated Distant Receivers

Abstract

We consider the problem of unknown emitter geolocation using the time difference of arrival (TDOA) of the path rays through the ionosphere by multiple coordinated distant receivers. We formulate the geolocation in the sense of maximum likelihood with the exact ray expressions for the quasi-parabolic (QP) ionosphere, which is a highly nonlinear and non-convex optimization problem. By carefully studying the characteristic of the group path ray, we propose an efficient procedure to approach the optimal solution of the geolocation. Simulation results show that the geolocation error approaches the associated Cramer-Rao bound when the knowledge of the ionosphere is available. We also performed Monte Carlo runs to evaluate the performance of the geolocation when the knowledge of the ionosphere is not exactly known, e.g., the QP model parameters are perturbed. Simulation results show that the geolocation performance under the perturbation within a given certain range is acceptable.