ANALYSIS OF THE ORIENTATION OF AN EDMI CALIBRATION BASELINE USING ONLINE GNSS PROCESSING SERVICES

This study evaluated the orientation of the electronic distance measuring instruments calibration baseline at the Federal University of Pernambuco, using data from two CHCNAV i50 GNSS receivers. The data were processed through the AUSPOS and IBGE-PPP online services. The calibration baseline comprises seven pillars equipped with forcing center devices. After the field survey, data from all pillars were submitted in RINEX format to the two processing services. However, due to significant sky obstruction from a nearby building, reports were only received for pillars 4 and 6 from both services. Despite this limitation, the study proceeded using the P4-P6 alignment derived from the geodetic coordinates in the reports. Calculations were performed for geodetic azimuths, geodetic distances, and transformations into plane coordinates for both online processing services. Results were then compared with two previous studies that employed total station surveys. The observed plane distance differences were 0.1725m (AUSPOS) and 0.0235m (IBGE-PPP), corresponding to relative linear precisions of 1/518 and 1/3308, respectively. In this context, the IBGE-PPP service provided better precision, though it was still below the levels stated in its reports. The study recommends using its IBGE-PPP results cautiously for tasks requiring relative linear precision up to 1/3308. Additionally, for the pillars 4 and 6, it suggests longer GNSS occupation times (>8 hours) for applications demanding higher precision.