Space State Representation Product Evaluation in Satellite Position and Receiver Position Domain

Area of Science:

• Geodesy
• Satellite Navigation
• Geophysics

Background:

• Global Navigation Satellite Systems (GNSS) positioning accuracy is significantly impacted by satellite orbit and clock correction errors.
• International services like the International GNSS Service (IGS) provide real-time corrections to mitigate these errors in various applications.
• The IGS Real-Time Service (RTS) offers real-time orbits and clock corrections, with products generated by multiple analysis centers using diverse algorithms.

Purpose of the Study:

• To evaluate and analyze four IGS RTS products (IGC01, CLK01, CLK50, CLK90) for Global Navigation Satellite Systems (GNSS) positioning.
• To assess the impact of State Space Representation (SSR) correction streams on satellite position and clock accuracy.
• To determine the influence of different SSR streams on receiver positioning accuracy using Precise Point Positioning (PPP) and Single Point Positioning (SPP) methods.

Main Methods:

• Calculated geocentric real-time satellite vehicle (SV) coordinates and clock corrections, comparing them with final ephemerides from IGS, ESA, GFZ, and GRG.
• Utilized corrected satellite positions and clock corrections to compute receiver Precise Point Position (PPP) in kinematic mode.
• Evaluated the impact of SSR corrections on receiver Single Point Position (SPP) accuracy.

Main Results:

• Satellite position accuracy was better than 10 cm (average 3-5 cm), with clock correction residuals ranging from 2 cm to 17 cm.
• Differences in satellite position accuracy were observed between streams, dependent on the reference data used.
• In kinematic PPP, the CLK90 stream yielded the best results (3D RMS at 0.13 m), significantly outperforming IGC01.
• SPP tests showed a substantial accuracy improvement with all evaluated SSR streams compared to using only broadcast ephemeris.

Conclusions:

• The accuracy of satellite position and clock corrections varies between different IGS RTS streams, necessitating receiver-level evaluation.
• The choice of SSR stream significantly impacts kinematic PPP results, with CLK90 demonstrating superior performance.
• All evaluated SSR streams offer considerable improvements in Single Point Positioning (SPP) accuracy compared to traditional broadcast ephemeris.