Estimation of Differential Inter-system Biases between the Overlapping Frequencies of Gps, Galileo, Beidou and Qzss

Multiple global and regional navigation satellite systems are currently being developed. In addition to the already available GPS and GLONASS constellations, Galileo and BeiDou satellites have been launched, as well as one QZSS satellite and other regional satellites. At the same time GPS and GLONASS are being modernized. Highprecision positioning applications that rely on carrierphase ambiguity resolution are likely to benefit from the many more satellites and frequencies that become available. Advantage can be taken from the fact some of the frequency bands are overlapping between the different constellations, since these signals may be differenced relative to one common reference satellite, instead of selecting a reference satellite per constellation. However, in case of relative positioning based on multi-GNSS receivers of different manufacturers, it is necessary to correct the data for nonzero differential inter-system biases (DISBs). In this contribution we present values for the DISBs, for the identical frequencies of GPS and Galileo, Galileo and BeiDou, as well as GPS and QZSS, based on multi-GNSS data provided in the context of the MultiGNSS Experiment (MGEX).