Uncertainties Propagation in the Compatibility Process of References and Epoch of GNSS Coordinates

Abstract

This article intends to show the effect of the propagation of uncertainties in the process of compatibility of epoch and referential of the coordinates obtained in the GNSS (Global Navigation Satellite System). It seeks to present how the precision of the Transformation Parameters (PT) and the velocity of GNSS stations can affect the precision of the coordinates after the propagation of uncertainties in the compatibility of referential and epoch. This article also points out the influence on the positional quality of the coordinates. For this purpose, 75 stations from the RBMC (Brazilian Network for Continuous Monitoring of GNSS Systems) distributed in the Brazilian territory were used. Initially, the PT precisions were obtained between ITRF2014 and ITRF2000, where ITRF2014 is aligned to IGb14 and ITRF2000 to SIRGAS2000. At this stage, it was noticed that the precisions of the PTs are depreciated, mainly due to the number of references involved between the two realizations (ITRF2014, ITRF2008, ITRF2005, and ITRF2000 – four references). Then, the data processing steps were performed - the compatibility of referential and epoch of coordinates, as well as the propagation of uncertainties in the matching processes - in several simulations. Done that, it was possible to observe that the compatibility process made the precision of the coordinates notably worse, but more realistic, making the precision values of the coordinates, which were, on average, 1.8 mm and 0.8 mm in the east (e) and north (n) components in the Local Geodetic System (SGL) respectively to become 18 .5 mm and 20.2 mm in the components (e) and (n) respectively after the propagation of uncertainties in the reference frame transformation and coordinates update.