Doppler-Based Satellite-Borne Localization of Ground Electromagnetic Interferer

Accurate localization and effective suppression of ground electromagnetic interference (EMI) signals are critical to maintaining uninterrupted satellite operations and the quality of services. For EMI sources emitting certain waveforms, such as continuous-wave or phase shift keying signals, their localization exploiting the time-varying Doppler signature due to satellite motion is an attractive approach. The high-speed motions and complicated orbits of satellites render the Doppler signatures varying with a high dynamic range and nonlinear instantaneous frequency signatures. As such, their processing requires high complexity which may not be practical for real-time processing, particularly for on-orbit satellite implementation for which the computational capability is highly limited. In this paper, we develop a low-complexity approach to iteratively estimate both the location and Doppler signatures of EMI signals. We introduce virtual ground references around the sensed scenarios and compute the Doppler difference between the measured results and the predicted ones for the virtual ground reference positions. By considering such Doppler difference in lieu of the Doppler frequencies, the Doppler dynamic range and the slope of the instantaneous frequency signatures are reduced to facilitate more effective time-frequency analysis and EMI source localization. We further consider the use of multiple virtual ground references for performance improvement, and a simple EMI localization approach is proposed through the interpolation of the Doppler difference frequencies observed at these virtual references. The effectiveness of the proposed approach is verified using simulation results.