GPS/GLONASS Combined Precise Point Positioning with Receiver Clock Modeling.

Area of Science:

• Geodesy and Geomatics
• Satellite Navigation Systems

Background:

• Precise Point Positioning (PPP) accuracy is often limited by receiver clock bias and correlations with other parameters.
• Integrating Global Positioning System (GPS) and GLONASS enhances satellite visibility and geometric strength.

Purpose of the Study:

• To investigate the impact of receiver clock modeling on GPS/GLONASS combined PPP accuracy and convergence.
• To assess the effectiveness of different inter-system timing bias (ISB) models in improving PPP performance.

Main Methods:

• Mathematical models for GPS/GLONASS observation, stochastic, and receiver clock were established.
• Kinematic PPP tests were conducted using a week of data from IGS stations with high-stability atomic clocks.
• Analyses included different receiver clock modeling schemes and inter-system timing bias models.

Main Results:

• Receiver clock modeling significantly improved 3D positioning accuracy by 30-40% on average, with vertical component showing pronounced benefits.
• GPS/GLONASS combined PPP outperformed GPS-only PPP, enhancing accuracy and reliability, particularly under poor GPS conditions.
• Refined ISB models improved PPP performance under adverse observation conditions by reducing parameter correlations.

Conclusions:

• Receiver clock modeling is crucial for enhancing PPP accuracy and convergence, especially for the vertical component.
• The integration of GLONASS with GPS provides substantial benefits for PPP, improving robustness and reliability.
• Optimized modeling of receiver clock bias and inter-system timing bias is essential for achieving high-performance PPP.