An un-differenced epoch-piecewise parallel estimation of the GNSS satellite clock offsets

Precise Point Positioning (PPP) requires a satellite clock product with an interval of 30-s. It is indispensable to reestimate the high sampling product after orbit determination. However, as the number of navigation satellites increases, their generation efficiency is severely affected. Therefore, an un-differenced epoch-piecewise parallel clock offset estimation method is proposed. Based on 120 stations, the 30-s clocks of 118 satellites were parallel estimated by four blocks within 19 min with a 3.5 times improved efficiency. The standard deviations between the estimated clock and the released products are 0.06, 0.06, 0.29, 0.10, and 0.15 ns for GPS, Galileo, GLONASS, BDS2, and BDS3 MEO satellites, respectively. When the 30-s interval clock products are used than 300-s, the convergence time of kinematic PPP for the BDS/Galileo and GPS/BDS/Galileo/GLONASS improves by 22 % and 33 %, respectively, while the three-dimensional RMS decreases by 5 mm (10 %) and 12 mm (28 %), respectively.