Localizing Ground-Based Pulse Emitters via Synthetic Aperture Radar: Model and Method

Signals from ground-based emitters frequently cause interference to synthetic aperture radar (SAR). A typical class of such interference signals is the transmitted pulses of ground-based radar systems due to the spectrum sharing between the Earth exploration-satellite service (EESS; active) and radiolocation in International Telecommunication Union (ITU) radio regulations. In this article, we study the localization model and method of ground-based pulse emitters using SAR as the observation platform. Specifically, we first establish a nonlinear parametric observation model of pulse time of arrival (PTOA) based on SAR observation geometry, where the model parameters include the emitter position in SAR range-azimuth plane. Then, we approximate the PTOA observation model by a second-order polynomial and estimate the azimuth and range positions of the emitter from the polynomial coefficients. Finally, we perform numerical experiments to test the accuracy of the proposed PTOA localization method. The results show that our method can achieve meter-level azimuth accuracy and kilometer-level range accuracy. Moreover, we study the Cramér-Rao lower bound (CRLB) of the emitter location, and by comparison, we show that the root-mean-square error (RMSE) of the proposed method is only about 1.5 times coarser than that of CRLB, demonstrating that our method achieves near-optimal localization accuracy.