Table 4 Simulation strategy for main error terms of LEO observations.
Error Component | Simulation Strategy |
|---|---|
Geometric Range | Calculated based on given receiver coordinates and LEO satellite positions from STK simulation |
Receiver Clock Error | Simulated millisecond-level clock jumps; receiver clock error linearly increases from -0.5 ms to 0.5 ms per hour |
Satellite Clock Error | Cyclically assigned using IGS precise GPS satellite clock products (e.g., satellites 1–32, 33–64, … of the LEO constellation use clocks from GPS satellites G01-G32, G01-G32, …, respectively) |
Tropospheric Delay | Zenith hydrostatic delay computed using the GPT2w and Saastamoinen model50; Zenith wet delay adopts estimates from real-tracked static PPP solutions; Slant delay is obtained using the VMF mapping function51 |
Ionospheric Delay | Computed using Global Ionosphere Maps (GIM) |
Integer Ambiguity | A fixed random integer value is assigned to each continuous arc |
Observation Noise | Simulated as Gaussian white noise with an elevation-dependent standard deviation; Zenith pseudorange and carrier phase precision are set to 0.3 m and 3 mm, respectively |
