Taiwan Online Precise Point Positioning Service: Methodology and Test Results

Abstract

Online precise point positioning (PPP) computation services can bring substantial benefits to surveying engineering and its applications. This study introduces Taiwan’s first online PPP service, named Taiwan Online Precise Point Positioning Service (TOPS). TOPS uses a between-satellite single-differenced (BSSD) PPP model to process dual-frequency Global Positioning System (GPS) and Globalnaya Navigatsionnaya Sputnikovaya Sistema (GLONASS) measurements. Moreover, this study proposes a method of geodetic datum transformation from the International Terrestrial Reference Frame (ITRF) to Taiwan Geodetic Datum 1997 at epoch 2010.0 (denoted as TWD97[2010]), which is one of Taiwan’s official coordinate systems. The positioning performance of TOPS was tested. Results demonstrated that in terms of daily solutions, TOPS can provide accuracy comparable with that of other online services such as the Canadian Spatial Reference System Precise Point Positioning (CSRS-PPP). The positioning results were transformed from ITRF to TWD97[2010] and compared with predetermined fiducial coordinates, and the results indicated that although the largest discrepancy in the horizontal direction was about 5 cm, the overall accuracy of the transformation can satisfy the requirement of horizontal control surveys in Taiwan.