Analysis of the performance of the Galileo high accuracy service (HAS) using low-cost GNSS receivers for real-time monitoring of dynamic deformations

We present the first comprehensive evaluation of the Galileo high accuracy service (HAS) for real-time monitoring of dynamic deformations using low-cost (LC) Global Navigation Satellite Systems (GNSS) observations. Three types of experiments were conducted employing the single-axis shake table. Experiments simulated a wide range of dynamic scenarios, including sinusoidal oscillations, strong ground motions from the 1989 Loma Prieta and 1995 Kobe earthquakes, and permanent offsets that varied between 10 and 50 mm. Displacement estimates from high-cost (HC) real-time kinematics (RTK), LC RTK, LC real-time precise point positioning (RT-PPP), and LC Galileo HAS were compared against high-precision Linear Variable Differential Transformer (LVDT) measurements. Results show that LC Galileo HAS can detect dynamic displacements in real time with a level of accuracy that generally surpasses LC RT-PPP. For harmonic oscillations, Galileo HAS detects the dominant frequency. However, the amplitude values corresponding to the dominant frequency varied between 0 and 7.6 mm. In earthquake simulations, it provided more consistent tracking of ground motion than LC RT-PPP, although with larger errors than RTK-based methods. In the step function experiments, Galileo HAS detected several permanent offsets, but its performance decreased for larger displacements, with errors exceeding 30 mm. Despite these limitations, the findings confirm that Galileo HAS, even when applied with low-cost consumer-grade receivers, offers measurable potential for real-time structural health monitoring and earthquake early warning systems.