LEO-PNT GNSS Convergence Simulator

Modern GNSS accuracy depends on more than how many satellites are in the sky — it depends on how quickly their geometry changes. This simulator places a receiver on a real Kepler-orbiting Earth model alongside a slow-moving MEO GNSS constellation (GPS Block III / Galileo FOC / GLONASS-K2 / BeiDou-3 class, ~12 h orbits) and a fast-moving LEO augmentation layer (~97 min orbits), computes live GDOP from the actual visible-satellite geometry matrix, and integrates a simplified information-accumulation model to show position uncertainty converging in real time. Adjust the MEO and LEO satellite counts, elevation mask and time acceleration to see why low-orbit augmentation satellites — proposed for future multi-GNSS PNT layers — can shrink convergence time from tens of minutes to under a minute by sweeping through fresh geometry far faster than any MEO constellation can.