Error Source Analysis for Doppler Shift Based Opportunistic LEO-PNT With Starlink Signals

Winfried Stock, Robert T. Schwarz, and Andreas Knopp

Peer Reviewed

Abstract:	The Positioning, Navigation, and Timing (PNT) services provided by Global Navigation Satellite Systems (GNSS) have become a cornerstone of modern societies. In order to reduce dependence on GNSS, great efforts have been made to explore alternative PNT systems. One promising approach is to use signals from Low Earth Orbit (LEO) communication satellites as signals of opportunity for PNT (opportunistic LEO-PNT). This study presents a systematic and comparative analysis of the most relevant error sources affecting the positioning accuracy of a standalone, static opportunistic LEO-PNT receiver that performs multi-epoch Doppler shift measurements on the Starlink signals using the Primary Synchronization Sequence (PSS). The results indicate, that orbit errors have the most significant impact, particularly when using widely available online orbit information. Furthermore, the effect of short-term clock stability is shown to be particularly dependent on the duration of the signal observation used to generate individual frequency estimations. The influence of frequency estimation errors varies based on the signal duration used per frequency estimation and the receiver antenna gain. Meanwhile, the impact of geometric factors does not appear to pose a major obstacle to opportunistic LEO-PNT. The findings of this study provide valuable insights for future comparisons, e.g., for error budget evaluations and the system design of opportunistic LEO-PNT systems. Index Terms—Starlink, navigation, signals of opportunity
Published in:	2025 IEEE/ION Position, Location and Navigation Symposium (PLANS) April 28 - 1, 2025 Salt Lake Marriott Downtown at City Creek Salt Lake City, UT
Pages:	774 - 781
Cite this article:	Stock, Winfried, Schwarz, Robert T., Knopp, Andreas, "Error Source Analysis for Doppler Shift Based Opportunistic LEO-PNT With Starlink Signals," 2025 IEEE/ION Position, Location and Navigation Symposium (PLANS), Salt Lake City, UT, April 2025, pp. 774-781.
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