Dual-frequency static GNSS solution over fixing time using Trimble RTX-PP free online service: GPS Vs. GPS + GLONASS

This study assessed the performance of dual-frequency static solutions as a function of fixing time using the Trimble RTX-PP free online service under two scenarios: GPS-only and GPS+GLONASS. The results confirm that both approaches achieve centimeter-level accuracy even after 1 hour of observation. GPS-only yields accuracies of 0.5 cm, 0.7 cm, and 1.8 cm in the E, N, and H components, corresponding to 0.9 cm and 2 cm in 2D and 3D, respectively. In contrast, GPS+GLONASS provides 0.5 cm, 0.5 cm, and 1.2 cm in E, N, and H, with 2D and 3D accuracies of 0.7 cm and 1.4 cm, respectively. Millimeter-level accuracy is achieved faster with GPS+GLONASS, reaching the 1 mm level after 10 hours, 2 hours, and 12 hours in E, N, and H, respectively, compared to 17 hours, 3 hours, and 12 hours for GPS-only. This demonstrates a clear improvement in convergence time, particularly in the east component. While both solutions converge to comparable accuracy over longer observation periods, the inclusion of GLONASS consistently enhances solution stability and reliability. The improvement remains within a few millimeters overall but is more evident during shorter observation durations, especially within the first hour, where increased observation redundancy and improved satellite geometry play a critical role. In conclusion, Trimble RTX-PP provides precise and reliable dual-frequency static differential-GNSS solutions suitable for most engineering applications. Although GPS-only delivers high accuracy, the integration of GLONASS offers faster convergence and improved stability, particularly for short fixing times, with measurable gains at the millimeter level.