Impact of Galileo data on the solutions of the variometric approach for displacement analysis

The Variometric Approach for Displacement Analysis Standalone Engine (VADASE) was successfully applied for seismological and monitoring purposes using GPS observations. In this work, GPS inter-operable and specific signals transmitted by Galileo satellites were considered to evaluate the impact of Galileo observations on VADASE solutions. The repetition period of the Galileo constellation was investigated to identify the time-windows with the most abundant number of Galileo satellites. Observation packages of about 15 min at 1 Hz were analyzed. Comparisons between the GPS derived and the Galileo derived VADASE solutions were performed after the identification of satellite configurations presenting the same number of satellites and similar geometries. Galileo and GPS combined solutions were also investigated. Single frequency and iono-free phase observations from a set of IGS-MGEX sites were processed in order to evaluate the sensitivity of the VADASE solutions with respect to a zero-displacement scenario. Galileo derived solutions are, in general, of good quality, essentially comparable to or better than the GPS derived solutions. The preliminary results enhance the contribution of Galileo system and pave also the way to a wider use of low-cost single frequency receivers for specific monitoring applications. The state of the undergoing development of the VADASE software for the combined processing of GPS and Galileo data are also presented. (C) 2019 COSPAR. Published by Elsevier Ltd. All rights reserved.