High-rate real-time single-frequency PPP for structural motion detection in horizontal directions

Thanks to advances in receiver and software technology, the high-rate GPS (Global Positioning System) technique has become very important in monitoring the dynamic behavior of man-made structures in both real-time and post-missions. Real-time monitoring of the changes in the behavior of structures due to effects such as natural disasters, wind effect, traffic loading is critical in order to take precautions in time. In this study, the performance of the Real-Time Single Frequency Precision Point Positioning (RT SF-PPP) method based on IGS (International GNSS Service) RTS (real-time stream) products to capture the behavior of dynamic motions was evaluated. The performance of the SF RT-PPP method to detect dynamic behaviors was evaluated based on 20 Hz single frequency GPS observations obtained from shake table experiments, including 10 mm amplitude and different oscillation frequencies including 0.1, 0.6, 1.0, 2.0 and 3.0 Hz. RT SF-PPP results were compared with reference LVDT (Linear Variable Differential Transformer) and relative (or double difference) GPS positioning both frequency and time domain. Results show that the high-rate RT SF-PPP method can capture the frequencies and amplitudes of harmonic motions and it is comparable to LVDT and Relative GPS positioning solutions. These results show that the high-rate RT SF-PPP method can monitor earthquake-induced real-time vibration frequencies and amplitudes, which is especially important for early warning systems.