Exploring GNSS RTK Performance Benefits with GPS and Virtual Galileo Measurements

摘要

kinematic (RTK) positioning are the strong distancedependence and unreliable ambiguity resolution under degraded observation conditions. While use of multiple frequency GNSS signals could possibly redefine future GNSS RTK services locally, regionally and globally, more redundant measurements from multiple satellite systems, such as GPS, Galileo and Glonass, can improve the performance of RTK solutions in terms of accuracy, availability, reliability and time to ambiguity fix. The direct benefits of these advancements for all scales of GNSS services are 1) significant savings in reference station infrastructure and operational costs, and 2) potential improvement on RTK availability and reliability for most of the professional users in the future. rnThis paper aims to study how the RTK system with multiple satellite constellations works and performs, using GPS and virtual Galileo dual-frequency measurements. Virtual Galileo measurements are obtained from the same set of GPS data, but starting from the epoch in 1 or 2 hours later. To proceed, generic linear equations for Ambiguity Resolution (AR) and position estimation are outlined for GPS and Virtual Galileo measurements first and various performance parameters for ambiguity resolution (AR) and RTK solutions are defined generally in order to more comprehensively evaluate a RTK system. Numerical analysis is performed using the research version of a postprocessing RTK software package, and results from three RINEX dual frequency data sets are given against various computing schemes, such as L1/L2 and widelane signals, GPS and virtual Galileo measurements. The performance results have preliminarily demonstrated the significant improvement due to the doubled number of measurements. Further improvements on the success rates are anticipated if refined modelling strategies for systematic and random errors in the double-differenced measurements are introduced.