Super GNSS Odometry: Long-Horizon Relative Constraints with Time Differenced Carrier Phase Error Correction

Daiki Niimi, An Fujino, Taro Suzuki, Junichi Meguro

Peer Reviewed

Abstract:	This paper proposes a high-accuracy GNSS relative positioning method based on time-differenced carrier-phase (TDCP) measurements. TDCP-based trajectory estimation integrates sequential relative displacements over time and therefore suffers from drift as small residual errors accumulate. To suppress this drift, prior work introduced loop closure into TDCP-based GNSS odometry by adding long-duration TDCP constraints between temporally distant states within a factor graph optimization (FGO) framework. However, the constraint interval was limited to at most 60 s because TDCP reliability degrades with increasing time difference due to residual satellite orbit/clock and atmospheric errors. To overcome this limitation, we analyze how residual orbit/clock, ionospheric, and tropospheric errors grow with the TDCP time difference, and we quantify the impact of each correction component by replacing it from a proposed baseline configuration with conventional methods. Based on these insights, we construct an FGO formulation that uses precise ephemeris/clock products and an ionosphere-free linear combination, and includes the zenith total delay as a state variable to explicitly estimate tropospheric variations. To clearly validate the effect of long-duration constraints, we evaluate a simplified loop-closure setting using a single TDCP factor with a 1000 seconds interval that directly connects the start and end states. Experiments in a static open-sky environment demonstrate that the proposed method suppresses error accumulation and reduces the maximum 3D relative positioning error to 9.35 cm.
Published in:	Proceedings of the ION 2026 Pacific PNT Meeting April 13 - 16, 2026 Hilton Waikiki Beach Honolulu, Hawaii
Pages:	561 - 571
Cite this article:	Niimi, Daiki, Fujino, An, Suzuki, Taro, Meguro, Junichi, "Super GNSS Odometry: Long-Horizon Relative Constraints with Time Differenced Carrier Phase Error Correction," Proceedings of the ION 2026 Pacific PNT Meeting, Honolulu, Hawaii, April 2026, pp. 561-571. https://doi.org/10.33012/2026.20633
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