StarAngle: User Orientation Sensing with Beacon Phase Measurements of Multiple Starlink Satellites

Low Earth Orbit (LEO) satellite networks have been growing very rapidly in recent years. In this paper, we propose a novel method, called StarAngle, which estimates user orientation with the beacon signals of Starlink satellites. StarAngle measures the beacon phase difference between two receiving antennas because the phase difference is a function of the user orientation. The phase measurements are compared with mathematical calculations based on known orbital parameters of Starlink satellites and the value that leads to the best agreement is used as the estimation. We overcome challenges due to asynchronous clocks in our commodity antennas by subtracting the phase measurements of one satellite by another which cancels the biases caused by clock mismatch. We experimentally test StarAngle in 10 locations under challenging weather conditions and our results show that the median estimation error is 7.5 degrees. Our results also confirm that the phase information of Starlink satellites can be measured reliably and may be used to support other applications in addition to user orientation estimation.