Characteristics of phase bias from CNES and its application in multi-frequency and multi-GNSS precise point positioning with ambiguity resolution

Abstract

While precise point positioning ambiguity resolution (PPP AR) is a valuable tool of the multi-constellation global navigation satellite system (multi-GNSS), phase biases are critical to implement PPP AR. Multi-frequency phase biases and satellite attitude files are provided freely by Centre National d’Etudes Spatiales (CNES), which are estimated based on GeoForschungs Zentrum (GFZ) satellite rapid orbit and clock products. However, the temporal characteristics of these phase biases and their positioning performance in the multi-frequency and multi-GNSS PPP AR have not been investigated yet, especially in the low sun elevation and satellite maneuver period. We introduce the transformation between multi-frequency phase biases and integer recovery clock model. In this transformation, inter-frequency clock biases (IFCBs) and inconsistencies in satellite attitude model errors between GFZ and CNES products are well considered. Experiments with GPS/Galileo/BeiDou observations from 34 stations were performed in static and kinematic modes, and the multi-frequency phase residuals were analyzed in the low sun elevation. Our results show that the impact of IFCBs and inconsistencies in satellite attitude errors could be mitigated at the user ends by using phase biases and satellite attitude files. Under the condition of satellite reverse yaw maneuvers, the performance of kinematic PPP without phase biases or deleting maneuvering satellites would be degraded significantly until the end of satellite observation arc or the next reverse yaw maneuver occurs. By applying phase biases with PPP AR, the positioning accuracy could be improved by 34.4%, 23.1%, and 37.4% in the east (E), north (N), and up (U) directions, respectively. Therefore, we suggested that PPP users should apply phase biases and satellite attitude files when using the GFZ rapid orbit and clock products, especially for satellite maneuvers and low sun elevation.