High-rate Single-Frequency Precise Point Positioning (SF-PPP) in the detection of structural displacements and ground motions

Abstract

This study presents the usability of the high -rate single -frequency Precise Point Positioning (SF -PPP) technique based on 20 Hz Global Positioning Systems (GPS)-only observations in detecting dynamic motions. SF -PPP solutions were obtained from post -mission and real-time GNSS corrections. These include the International GNSS Service (IGS)-Final, IGS real-time (RT), real-time MADOCA (Multi-GNSS Advanced Demonstration tool for Orbit and Clock Analysis), and real-time products from the Australian/New Zealand satellite -based augmentation systems (SBAS, known as SouthPAN). SF -PPP results were compared with LVDT (Linear Variable Differential Transformer) sensor and single -frequency relative positioning (SF -RP) solutions. The findings show that the SF -PPP technique successfully detects the harmonic motions, and the real-time productsbased PPP solutions were as accurate as the final post -mission products. In the frequency domain, all GNSS-based methods evaluated in this contribution correctly detect the dominant frequency of short-term harmonic oscillations, while the differences in the amplitude values corresponding to the peak frequency do not exceed 1.1 mm. However, evaluations in the time domain show that SF -PPP needs high-pass filtering to detect accurate displacement since SF -PPP solutions include trends and lowfrequency fluctuations, mainly due to atmospheric effects. Findings obtained in the time domain indicate that final, real-time, and MADOCA-based PPP results capture short-term dynamic behaviors with an accuracy ranging from 3.4 mm to 8.5 mm, and SBAS-based PPP solutions have several times higher RMSE values compared to other methods. However, after high-pass filtering, the accuracies obtained from PPP methods decreased to a few mm. The outcomes demonstrate the potential of the high -rate SF -PPP method to reliably monitor structural and earthquake -induced ground motions and vibration frequencies of structures.