GPS 위성 궤도력에 따른 단독측위 정확도 비교 분석 = Comparative Analysis of Point Positioning Accuracy Based on GPS Satellite Ephemeris

다국어 초록 (Multilingual Abstract)

This study aims to quantitatively examine the validity and limitations of instantaneous single-epoch positioning by comparing and analyzing the standalone positioning accuracy according to the type of GPS satellite ephemeris. The study targets six geodetic sites, including a Unified Control Point, a Benchmark, and Continuously Operating Reference Stations (CORS). For satellite coordinates, broadcast ephemeris were derived using navigation message parameters, while precise ephemeris were obtained from IGS-provided sp3 files and interpolated by a 9th-order Lagrange polynomial, allowing comparison under identical conditions. The same basic corrections were applied throughout the study, including satellite clock correction, relativistic corrections based on orbital eccentricity, ionospheric corrections using the Klobuchar model, dual-frequency ionospheric corrections, tropospheric corrections using the Hopfield model (simplified), and Sagnac corrections. The multivariate Newton-Rapson algorithm was applied to the satellite-receiver observation equations, and the receiver position was determined through iterative calculations. The analysis results showed that the pure 1-epoch coordinate accuracy based on broadcast ephemeris was generally around 4-5 m at both the Chitrakut Station in 2006 and the domestic surveying control points from 2023 to 2025, with little difference between periods. On the other hand, the coordinate accuracy based on precision ephemeris only improved by about 0.5 m compared to the broadcast ephemeris in 2006, but between 2023 and 2025, the error decreased by more than 2 m at most points, reaching an average of 1.5 m. This improvement is interpreted as due to the advancement of precision orbit and clock calculation techniques provided by international GNSS analysis centers such as IGS over the past 20 years, the expansion of tracking networks, integrated multi-GNSS processing, and the advancement of Earth rotation and tidal model corrections. Therefore, this study is an empirical comparison of the difference between broadcast ephemeris and precision ephemeris at the single-epoch coordinate level, and can serve as important basic data for suggesting the applicability of real-time precision positioning techniques, improvement of correction models, and usability in the fields of navigation and surveying in the future.