Short-term forecast for GPS/BDS-2 inter frequency clock bias based on improved harmonic fitting model and its application on triple-frequency PPP

To reduce the calculation burden of GPS and BDS-2 triple-frequency precise point positioning (PPP), a short-term inter-frequency clock bias (IFCB) prediction method was proposed for the GPS Block IIF satellites and BDS-2 satellites. The important innovation of this method is to fit the period lag time relative to 24 hours instead of estimating the IFCB period, and only a short IFCB basic sequence is needed to perform high-precision forecasting with multiple days of lag. After applying these predicted IFCBs, the static/kinematic positioning accuracies can be improved by 16–25%/25–33% for GPS and by 10–19%/22–27% for GPS/BDS-2.