Single-station TLE estimation of NC-LEO satellite for space-based opportunistic positioning

The space-based opportunistic positioning is an integral part of the resilient positioning, navigation, and timing (PNT) system. At the moment, most space-based opportunistic positioning terminals depend on the non-cooperative low Earth orbit (NC-LEO) satellite’s unreliable and imprecise orbit. To address this problem, this paper presents a framework for single-station two line element (TLE) estimation of non-cooperative low Earth orbit satellites. The precise TLE is obtained using Doppler observations from a single-station and the orbital parameters for constellation design. Additionally, a TLE estimation algorithm is proposed based on a genetic algorithm-ridge estimation approach with multiple initialization strategies. This method facilitates the acquisition of accurate TLE even in situations where prior orbit information is incomplete, and when the problem is ill-conditioned. Finally, real-world tests confirm that using TLEs computed using the suggested method leads to improved accuracy when compared to placement based on NORAD’s publicly available TLEs.