Estimation of the inter-frequency clock bias for the satellites of PRN25 and PRN01

We present two efficient approaches, namely the epoch-differenced (ED) and satellite- and epoch-differenced (SDED) approaches, for the estimation of IFCBs of the two Block IIF satellites. For the analysis, data from 18 stations from the IGS network spanning 96 d is processed. Results show that the IFCBs of PRN25 and PRN01 exhibit periodical signal of one orbit revolution with a magnitude up to 18 cm. The periodical variation of the IFCBs is modeled by a sinusoidal function of the included angle between the sun, earth and the satellite. The presented model enables a consistent use of L1/L2 clock products in L1/L5-based positioning. The algorithm is incorporated into the MGPSS software at SHAO (Shanghai Astronomical Observatory, Chinese Academy of Sciences) and is used to monitor the IFCB variation in near real-time.