M_IFCB: a MATLAB-based software for multi‑GNSS inter‑frequency clock bias estimation and forecast

To address the lack of publicly available inter-frequency clock bias (IFCB) products and the impact of IFCB on real-time or near-real-time multi-frequency precision positioning, a MATLAB-based software for multi-GNSS IFCB estimation and forecast (M_IFCB) was produced for multi-frequency users. This software can estimate the IFCB of GPS, BDS-2, Galileo and BDS-3 satellites and provide three alternative forecast models for GPS satellites with large IFCB amplitude variations. To verify the availability of M_IFCB, 194 and 41 globally evenly distributed MGEX continuous tracking stations were used for IFCB estimation and GPS triple-frequency uncombined precise point positioning (PPP) performance evaluation, respectively. The results show that the precision of the static solutions of the triple-frequency uncombined PPP increased by about 20.4% in the horizontal direction and 18.5% in the vertical direction, respectively. Incorporating the predicted IFCB correction, the precision of the static solutions increased by about 19.9% in the horizontal direction and 17.6% in the vertical direction, respectively.