Evaluation of the performance of web-based GNSS post processing platforms at selected permanent CORS stations in Uganda.

Abstract

In recent years, several web-based GNSS post processing and data evaluating services have been developed for less-skilled GNSS users by various institutions. Even basic GNSS positioning and data evaluation application users can benefit from these services. These processing services are convenient, fast, reliable and cost effective which is not the case for conventional GNSS processing techniques. However, users of Web-based processing services have limited influence on settings and processing data flow, thus the quality of the positioning solution is independent on one’s skills. It is therefore important that these services be subjected to a meaningful evaluation so as to ascertain the quality of their solutions. The aim of this study was to evaluate the performance of Web-Based GNSS Post-Processing services in Uganda. This study utilized GNSS observation data from five SURVNET CORS stations (KLA1, MBLE, JJA2, MBRA and HOIM). The observation data was decimated to obtain observation sessions of 1-hour, 2-hours, 3-hours, 6-hour, 8-hours and 12-hours. The decimated data was then processed by seven web-based GNSS post processing services. The processed solution coordinates were received via email. The precision and accuracy analysis of the solution coordinates was done by analysing the standard deviations and root mean square errors for both plane and elevation coordinates. Results show that increasing lengths of observation sessions significantly improved the precision of the plane and elevation coordinates. CSRS service produces more accurate solution coordinates than other services that employ the PPP technique. AUSPOS produces the most reliable solution coordinates among services that utilize the relative positioning technique. Overall, AUSPOS produces more accurate plane coordinates with HRMSEs which range between 0.061m- 0.072m. CSRS on the other hand gives the best overall elevation coordinates, with VRMSEs which range between 0.015m – 0.019m.