An Analysis of Online GNSS Postprocessing Services in for Short Occupation Times in Bolivia and Colombia

Several online GNSS data processing services are available as an alternative solution to expensive and time consuming scientific and commercial GNSS post-processing tools. These alternatives are typically free and simple to use with centimeter to decimeter-level accuracy. To utilize these online services for static processing, occupation times typically need to be at least two hours long to produce acceptable accuracies. This requirement presents logistical and financial constraints for surveyors and scientists when planning for GNSS field campaigns. This study focuses on assessing the parameters that influence the accuracy of some of the more popular of these services, namely AUSPOS, APPS, CSRS-PPP, GAPS, OPUS, and SCOUT. The data set used in this study consists of 2-4 hour occupation times that come from geodetic surveys conducted in Bolivia and Colombia that span from 2010 to 2020. To measure against a benchmark, the results from each service were evaluated against the high-accuracy scientific software, GAMIT. The estimated coordinates of each service were differenced with the those obtained from GAMIT to determine the accuracy of each service. The standard deviations of each service were quantified to determine their respective precision.