Positioning with Starlink LEO Satellites: A Blind Doppler Spectral Approach
Sharbel Kozhaya, Zaher M. Kassas
Abstract
A blind Doppler spectral approach is proposed for exploiting unknown Starlink low Earth orbit (LEO) satellite signals for positioning. First, an analytical derivation of the received signal frequency spectrum is presented, which accounts for the highly dynamic channel between the LEO satellite and a ground-based receiver. Second, a frequency domain-based blind Doppler discriminator is proposed. Third, a Kalman filter (KF)-based Doppler tracking algorithm is developed. Finally, experimental results are presented of a stationary receiver tracking the Doppler, in a blind fashion, of six Starlink LEO satellites over a period of about 800 seconds with Hz-level accuracy. The Doppler measurements were fused through a nonlinear least-squares estimator to localize the receiver to an unprecedented level of accuracy. Starting with an initial estimate 200 km away, the proposed approach achieved a final horizontal two-dimensional (2D) position error of 4.3 m.