Abstract
From November 27, 2022, IGS has switched to using the new reference frame ITRF2020 instead of the old reference frame ITRF2014 in its precise point positioning (PPP) products. To examine the effect of changing the reference frame on the PPP coordinate series, we used GNSS data in 2022 of 9 CORS stations evenly distributed in the territory of Vietnam. GNSS data is PPP processed using NRCan's CSRS-PPP service. The analysis results on the coordinate series over time show that the North and East components have changed systematically from November 27, 2022, and the average value of the deviation is +3.9 and +2.9 mm, very close to the value calculated from the 7 transformation parameters +3.2 and +1.8 mm. The change in the height series occurs about 14 days earlier than the horizontal and has a deviation of up to -19.4 mm, completely different from the calculated result of ~-0.3 mm