Applicability of low-cost GNSS receivers for detecting dynamic displacements: a shake table experiment case study

Abstract The high cost of geodetic-grade GNSS receivers limits the development of dense early warning systems for earthquakes. While high-rate GNSS observations enable direct displacement measurements without cumulative integration errors, the deployment of dense GNSS networks remains economically challenging and thus low-cost receivers have gained attention for such monitoring. In this study, we assess the performance of the low-cost Septentrio Mosaic-X5 GNSS module for dynamic displacement detection under a controlled field experiment. The results were compared with those obtained from a geodetic-grade Trimble Alloy receiver. Harmonic oscillations with frequencies ranging from 0.5 to 4 Hz and amplitudes from 20 to 2.5 mm were generated using a Quanser I-40 shake table. Both receivers were connected to a common antenna, and the recorded data were processed using the Variometric Approach for Displacements Analysis Stand-Alone Engine (VADASE) algorithm. While both devices reproduced sinusoidal motions and correctly identified frequencies, we observed a consistent amplitude overestimation. The highest deviation occurred at the 2 Hz frequency and 10 mm amplitude motion. In this scenario, the Trimble and Septentrio receivers output 17.0 mm and 11.6 mm amplitudes, respectively. Despite the amplitude offsets, the system reliably detected the minimum 2.5 mm excitation at 4 Hz, demonstrating its utility for precise monitoring. Moreover, the analysis showed that the low-cost sensor has a lower noise level in the high-frequency domain than the reference device. These findings indicate that low-cost GNSS receivers combined with the VADASE algorithm are sufficient for detecting microseismic events, enabling the mass deployment of low-cost monitoring networks.