Assessing the performance of GNSS PPP-AR using OSB products from different analysis centers

Integer ambiguity resolution (AR) has been demonstrated to be an effective approach to reduce convergence time and improve accuracy for Precise Point Positioning (PPP) technology. Many bias products have been employed for PPP-AR, including wide-lane uncalibrated phase delays (UPD), narrow-lane UPD, and re-estimated clocks merged with ionosphere-free UPD. Recently, observable-specific signal bias (OSB) products that can be directly applied to raw observations are preferred by International GNSS Service (IGS). Several IGS Analysis Centers (ACs) now release independent orbit, clock and OSB products on a regular basis. To evaluate the performance of the OSB products and IGS precise products from different ACs, this study investigated the performance of GPS-only and multi-GNSS combined PPP-AR using satellite products from four ACs: National Center for Space Studies (CNES), Wuhan University Multi-GNSS Experiment (WUM), Center for Orbit Determination in Europe (CODE), and German Research Centre for Geosciences (GFZ). Observations from 30 IGS MGEX stations over 15 days with an interval of 30 s were processed in PPP static solution, and the results indicate that the float solution is minimally affected by the choice of satellite product but a significant influence on the fixed solution. In general, the CODE products outperform the others in terms of positioning performance. For GPS/Galileo/BDS combined PPP-AR, the satellite products from GFZ outperform those from WUM. Furthermore, the convergence time to achieve centimeter-level coordinate accuracy is approximately 13 min for GPS-only PPP-AR, while can be shortened to about 6 min for GPS/Galileo PPP-AR. However, the GPS/Galileo/BDS PPP-AR reduces the convergence time by about 0.5–1.6 min compared to GPS/Galileo PPP-AR.