Quality of static PPP over observation time using PPP-WIZARD free online service: GPS VS. GPS + GLONASS
Associated Professor of Engineering Surveying and Space Geodesy, Department of Civil Engineering, Benghazi University, Benghazi, Libya.
Research Article
Open Access Research Journal of Science and Technology, 2025, 15(02), 195-200.
Article DOI: 10.53022/oarjst.2025.15.2.0150
Publication history:
Received on 15 November 2025; revised on 24 December 2025; accepted on 26 December 2025
Abstract:
The Global Positioning System (GPS) provides accurate, continuous, and worldwide positioning and timing information through satellite-based observations. However, dependence on a single satellite constellation introduces constraints related to satellite visibility and geometric configuration, which may negatively influence positioning reliability, particularly in situations where satellite geometry is weak or visibility is limited. This study investigates the performance of static Precise Point Positioning (PPP) as a function of fixing time using the PPP-WIZARD online service under two processing strategies: GPS-alone and combined GPS+GLONASS. The analysis was carried out under open-sky conditions to minimize multipath effects. Dual-frequency GNSS observations were collected from ten well-distributed stations across Libya, with continuous data acquisition over 24-hour sessions at each site. Static PPP solutions were computed for fixing intervals starting from 1 hour and progressively extending to 24 hours. The 24-hour static PPP solution was adopted as the reference to assess the accuracy and stability of the shorter-duration solutions. The results indicate that incorporating GLONASS observations with GPS significantly enhances solution robustness and positioning stability across all fixing intervals. These improvements are most pronounced during shorter observation periods, particularly within the first hour, where the absolute errors in the East, North, Height, 2D, and 3D components are reduced by approximately 6 cm, 6.5 cm, 11 cm, 9 cm, and 13 cm, respectively, when using the GPS+GLONASS configuration. The advantages of the multi-constellation approach are also evident during the initial hours, when PPP solutions are highly sensitive to satellite geometry and convergence characteristics. Although the improvement in mean absolute positional accuracy becomes less significant for longer observation durations, the integration of GLONASS substantially reduces the presence of outliers and decreases the dispersion of coordinate residuals in all components. The findings demonstrate that even under ideal open-sky conditions, where multipath effects are negligible, the inclusion of GLONASS contributes measurably to enhancing the robustness and reliability of static PPP solutions. In agreement with previous research, the results confirm that the PPP-WIZARD service in static mode yields higher-quality solutions compared to kinematic mode, particularly when using GPS-alone observations, while superior performance in both static and kinematic modes can be achieved using other online services such as CSRS-PPP. In summary, although the long-term improvement from integrating GLONASS with GPS in static PPP-WIZARD processing is marginal compared to GPS-alone solutions, the benefits are substantial during the early fixing stages. Notably, the positioning quality achieved using one-hour static dual-frequency PPP with GPS+GLONASS is comparable to that obtained after approximately 3–4 hours of fixing time when relying solely on GPS.
Keywords:
GPS; GLONASS; Precise Point Positioning (PPP); PPP-WIZARD; Static Positioning; Fixing Time
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Copyright © 2025 Author(s) retain the copyright of this article. This article is published under the terms of the Creative Commons Attribution Liscense 4.0