Single Satellite Emitter Geolocation in the Presence of Oscillator and Ephemeris Errors

This paper addresses high-accuracy geolocation of a ground-level, uncooperative RF emitter using a single low earth orbit (LEO) satellite. It is meant to be a real-time, single-pass solution that requires only a few seconds of Doppler and Doppler Rate measurements and resistant to erroneous ephemeris readings and oscillator errors from both the transmitter and receiver. The presented work can be expected to have a significant impact on search and rescue operations, spectrum monitoring, and tracking. Oscillator and ephemeris errors are inherent system flaws for satellite geolocation - heavily distorting error distributions, violating many symmetric and Gaussian assumptions that most estimation algorithms rely on. To deal with this, a constrained Unscented Particle Filter (cUPF) is provided. Using quoted oscillator errors, ephemeris error, analysis is provided with respect to geolocation accuracy. Each scenario compares the cUPF with a previously developed constrained Unscented Kalman Filter (cUKF). Validation is provided on both simulated data and off-the-air IQ data obtained from the TDS-1 Satellite operated by Surrey Satellite Technology. The cUPF algorithm outperforms the prior state-of-the-art cUKF in both accuracy and convergence time, often obtaining single kilometer geolocation accuracies with only a few seconds of acquisition time over a several hundred kilometer search space.