Analysis of the Accuracies of CSRS-PPP and AUSPOS Online Post-Processing Services

Abstract

The static mode of point positioning requires post-processing, which can be done automatically using some of the free online post-processing services. It is, therefore, important to evaluate the accuracy of coordinate solutions provided by these services, determine the optimal observation duration to achieve specific accuracy levels, identify when longer observation durations yield less accuracy improvement, and compare the overall accuracy performance of online post-processing services. In this study, the accuracies of two free online post-processing services (CSRS-PPP and AUSPOS) were tested using data acquired at three Continuously Operating Reference Stations (CORS) located at Asaba, Benin and Warri, all located in Southern Nigeria. The acquired 8 hours Global Navigation Satellite System (GNSS) observation data recorded in RINEX (Receiver Independent Exchange) format version 3.05 were decimated into shorter sessions of (15 minutes, 30 minutes, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, and 6 hours). The findings show that both services produced centimetre-level horizontal accuracy. However, CSRS-PPP achieved 10 cm accuracy within 15 minutes compared to 1 hour with AUSPOS, but the rate of accuracy improvement with both services decreased significantly after 2-3 hours. Also, from 14 performance evaluation criteria at each of the three stations totaling 42 total comparisons used in the study, CSRS-PPP won 29 out of 42 (69%). This study provides important practical information for geospatial professionals on which service offers better accuracy and which works faster.