TIME AND FREQUENCY TRANSFER COMBINING GLONASS AND GPS DATA

摘要

Measurements from Global Navigation Satellite Systems (GNSS) have been used since the eighties to perform precise and accurate Time and Frequency Transfer (TFT). Two main approaches are used presently: the Common View or All in View based on the Common GPS GLONASS Time Transfer Standard (CGGTTS) and the Precise Point Positioning (PPP). Concerning the CGGTTS approach, in order to allow the use of GLONASS data from geodetic-type receivers providing only raw data in RINEX format, the R2CGGTTS software developed initially for GPS at the Royal Observatory of Belgium (ROB) was updated. The GLONASS navigation files are used for the determination of satellite clocks and positions, and the computation procedure to get the CGGTTS data from the pseudorange measurements is applied similarly as for the GPS satellites. In parallel, we also upgraded the PPP software Atomium developed at the ROB to allow the use of the Russian GLONASS constellation. The clock solution is then obtained through the analysis of dual-frequency carrier-phase and pseudorange measurements. This study combines GPS and GLONASS observations in PPP in order to determine the added value of the GLONASS data in geodetic time transfer.