Starlink for PNT: A Trick or a Treat?

This paper studies the exploitation of donwlink Starlink low Earth orbit (LEO) satellite signals for positioning, navigation, and timing (PNT). First, the paper reveals, for the first time, the full Starlink orthogonal frequency division multiplexing (OFDM) beacon, spanning the whole time-frequency resource grid. This is achieved through blind beacon estimation, where it is shown that the Starlink’s sequences published in the literature only comprise 0.66% of Starlink’s full OFDM. The exploitation of the full OFDM beacon is shown to increase the receiver’s process gain by nearly 18 dB compared to only using signals published in the literature. This process gain unlocks higher effective signal-to-noise ratio (SNR) at the receiver’s correlator output, enabling reliable acquisition and tracking in low SNR regimes imposed by using low-gain antennas. Second, the paper shows the first experimental results of extracting OFDM-based Doppler observables from Starlink satellites. Third, the paper demonstrats the first positioning solution with OFDM-based Doppler shift exclusively. Unprecedented results are presented showing that with an average of 3 active Starlink satellites, snapshot positioning with a three-dimensional error of 2 meters is achieved in 20 seconds.