The phase and code biases of Galileo and BDS-3 BOC signals: effect on ambiguity resolution and precise positioning

The modernization of GPS and GLONASS and the development of BDS and Galileo make a variety of new navigation signals available to the users. The wide range of GNSS signals will result in various biases that need to be considered in data processing. In particular, Galileo and BDS-3 binary offset carrier (BOC) signals employ a new approach called dual-frequency constant envelope multiplexing. In this contribution, the phase and code biases of Galileo and BDS-3 BOC signals were estimated and investigated with the observation of iGMAS and MEGX networks during the period of 2015–2018. Initial analyses of BDS-3 BOC signals indicate that satellite-specific pilot-minus-data code biases are close to zero for BDS-3 B2a and B2b signals, while the ones for B1C signal are not. In addition, the satellite differential code biases (DCBs) between Galileo E5a, E5b and E5ab signals, as well as between BDS-3 B2a and B2b signals, are also close to zero. The estimated phase biases for Galileo E5a, E5b and E5ab signals or BDS-3 B2a and B2b signals are the same values, and the resultant phase biases of the extra-wide-lane (EWL) combination are very close to the zero. Besides, no obvious time-varying inter-frequency clock bias could be observed for both Galileo and BDS-3 satellites. Such characteristics of phase/code biases of the new GNSS signals are valuable for ambiguity resolution and precise positioning. Only one set of code or phase bias product is required for Galileo E5a/b/ab (BDS-3 B2a/b) signals. The satellite DCBs between Galileo E5a, E5b and E5ab signals, as well as between BDS-3 B2a and B2b signals, can be ignored in the data processing. And the EWL ambiguities derived from the Galileo E5a/b/ab or BDS-3 B2a/b observations keep their integer feature and can be fixed to integers without phase bias corrections.