Evaluation of Indonesia’s Recent GNSS Online Data Processing

Accurate Global Navigation Satellite System (GNSS) data processing is generally done through post-processing using commercial or scientific GNSS data processing software. The use of these software tools requires costs, skills, and knowledge in its operation. Therefore, several countries have developed website services to process GNSS data online. Indonesia currently has the InaCORS online data processing (ODP) service developed by the Geospatial Information Agency (BIG; Badan Informasi Geospasial). This study aims to analyze performance and important aspects related to using ODP InaCORS and several ODP services for GNSS observations in Indonesia. The research methodology compared the results of coordinate processing in ODP (APPS, AUSPOS, CSRS-PPP, and InaCORS) with the results of processing in Bernese v5.2. The data used are static observational data at ITB1 and JOG2 points over 24 h. Data analysis was carried out using control points at InaCORS, varying the observation duration to 1, 3, 6, 12, and 24 h, and applying its use in Indonesia. The analysis of baseline length in data processing using InaCORS shows that the use of the baseline is particularly significant in short observation data (1–3 h). The level of horizontal coordinates using InaCORS produces an accuracy of under 3 cm and a geodetic height of under 7 cm, which can be achieved by static GNSS observations for 1 h. Even the accuracy of the horizontal coordinates over a period of 24 h may reach the millimeter level. At the same time, the results from the APPS, CSRS-PPP, and AUSPOS services have an accuracy of the easting and northing positions of about 26 and 9 cm, respectively. The discrepancies are due to the different epoch definitions used between different online GNSS data processing platforms. By using these three services to process GNSS data in Indonesia, the deformation parameters must first be corrected to be used in accordance with the actual position. Based on the assessment of speed and ease of data processing indicators, the InaCORS service requires further improvement.