ANALYSIS OF CORS POSITION TIME SERIES AND VELOCITIES USING PRECISE POINT POSITIONING IN THAILAND

Abstract

This research studies the movement behavior of Continuously Operating Reference Stations (CORS) in Thailand by analyzing time series data, velocity, and directional changes of station coordinates over time. Additionally, it examines the impact of CORS station displacement rates on the long-term closure accuracy of the CORS triangulation network. The study processes GPS satellite signal data from CORS stations within the RTK GNSS Network, covering the period from 2019 to 2023—five years. With precise point positioning (PPP) techniques using the GipsyX research software. The findings reveal that CORS stations in Thailand exhibit continuous southeastward movement at an average azimuth angle of 106° 29' 42.4" and an average velocity of 29 mm/year, with the most pronounced change occurring along the E-axis, followed by the N and U axes, additionally. Based on the maximum deviation over the next 30 years from Epoch 2024.0, the displacement of CORS stations significantly affects the closure accuracy of the CORS triangular network across most areas in Thailand. Compared to FGCS standards for satellite survey work, the impact falls within class A for 59.47% of the area, class AA for 25.95%, and class B for 10.40%. The results demonstrate that the CORS stations in Thailand maintain consistent velocity and directional movement patterns, significantly impacting positional closure discrepancies over time. This behavior also reflects tectonic movements in the region. Failure to account for these factors during data analysis could lead to inaccurate results.