Reference System and Accuracy Evaluation of InaCORS RTK and Online Data Processing Services

Abstract

Global Navigation Satellite System (GNSS) Real-time Kinematic (RTK) method is commonly used in Indonesia because it can produce three-dimensional position directly with accuracy of ±5 cm, which is transmitted from a reference station using Networked Transport of RTCM via Internet Protocol (NTRIP) communication media. InaCORS system provided by Badan Informasi Geospasial (BIG) become the easiest reference station solution with stations that is always on and spread out throughout Indonesia. The InaCORS system provides nearest RTK, virtual reference station (VRS) RTK, and online data processing (ODP) services. Currently, the Indonesia Geospasial Reference System (SRGI2013) has the epoch 2021 reference system. The aim of this research is to determine which epoch is used and the accuracy and precision of the RTK and ODP services of InaCORS. To determine this issue, this study conducted RTK nearest and RTK VRS data acquisition for 5 minutes with 1-second interval, as well as static measurement for three hours at 10 points spread out throughout Bandung. The acquired data was then compared with static data processed through CORS ITB to be considered as the true value. The compared results between the three services of the InaCORS system against the true value indicate that the InaCORS system still uses the 2012 epoch because the difference value is closer to epoch 2012 than to epoch 2021, with a difference between epochs up to 26 cm. The compared results state that ODP 3D accuracy is the highest of the three services with an accuracy of 3.93 cm because ODP process static data which is more stable than RTK data, with 3D precision of 3.97 cm. Between the RTK methods, VRS is more accurate with 3D accuracy of 5.05 cm and 3D precision of 4.03 cm. The nearest RTK method has 3D accuracy and precision respectively 5.65 and 3.87 cm, which is the best precision of all three services. Between the RTK methods, VRS can be said is better than nearest in terms of accuracy and precision, but nearest RTK is more stable and unlikely to fail in measurement than VRS.