Abstract
Compared with the double-difference relative positioning method, the precise point positioning (PPP) algorithm can avoid the selection of a static reference station and directly measure the three-dimensional position changes at the observation site and exhibit superiority in a variety of deformation monitoring applications. However, because of the influence of various observing errors, the accuracy of PPP is generally at the cm-dm level, which cannot meet the requirements needed for high precision deformation monitoring. For most of the monitoring applications, the observation stations maintain stationary, which can be provided as a priori constraint information. In this paper, a new PPP algorithm based on a sliding window was proposed to improve the positioning accuracy. Firstly, data from IGS tracking station was processed using both traditional and new PPP algorithm; the results showed that the new algorithm can effectively improve positioning accuracy, especially for the elevation direction. Then, an earthquake simulation platform was used to simulate an earthquake event; the results illustrated that the new algorithm can effectively detect the vibrations change of a reference station during an earthquake. At last, the observed Wenchuan earthquake experimental results showed that the new algorithm was feasible to monitor the real earthquakes and provide early-warning alerts.
Highlights
Natural hazards, such as earthquakes, landslides, subsidence and avalanches are crucial, but do not occur without warnings[1]
High precision real-time satellite orbit and clock products are already available from a number of IGS (International Global Navigation Satellite Systems (GNSS) Service) analysis centers, which will further promote GNSS real-time deformation monitoring applications[9]
The results demonstrated the validity of the new precise point positioning (PPP) algorithm in simulation coseismic experiment
Summary
Monitoring received: 19 October 2015 accepted: 03 May 2016 Published: 31 May 2016. Compared with the double-difference relative positioning method, the precise point positioning (PPP) algorithm can avoid the selection of a static reference station and directly measure the threedimensional position changes at the observation site and exhibit superiority in a variety of deformation monitoring applications. A new PPP algorithm based on a sliding window was proposed to improve the positioning accuracy. Data from IGS tracking station was processed using both traditional and new PPP algorithm; the results showed that the new algorithm can effectively improve positioning accuracy, especially for the elevation direction. The experimental results showed that, compared with the traditional algorithm, the new method can improves dynamic PPP precision dramatically, especially for the vertical direction, making it applicable for earthquake monitoring applications. The position accuracy was about 5 cm for the horizontal and 10 cm for the vertical after convergence, and the position results showed a consistent trend for all three days This might be a result of obvious changes of satellite distribution or the strong m-path effects, which would need further analysis. During coseismal monitoring, the time series of calculation results were analyzed to determine whether a coordinate transition hop occurred, so the systematic bias would have no impact on the determination
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