4 ms·

Can an error be compensated by the number of satellites?

• phreeza 6y ago
  Not an expert by any means, but from my experience with physics experiments I would guess the error goes down as 1/sqrt(n). So more satellites help, but with diminishing returns.
• dr_orpheus 6y ago
  Theoretically, yes. But you are already limited by the position knowledge of the OneWeb satellites themselves. Currently they rely on on-board GPS receivers for their position knowledge which is quoted as 10m (1σ) [0]. Timing knowledge is quoted as 50 ns (1σ), so when calculating time-of-flight from the satellite this will add another 15m of error. So you won't be able to get better than that number, and it will likely be significantly worse than that and you could get errors up in to the 100m range. With regular handlheld GPS receivers or smartphones you can usually get an accuracy of a couple of meters under open sky [1/2]. And if you get precision GPS receiver units which can use dual-band and differential GPS you can get down in to the centimeter accuracy range [3]. So there is a very big orders of magnitude difference with what you could do with the OneWeb satellites right now. [0] https://onewebsatellites.com/arrow/ https://onewebsatellites.com/arrow/ [1] https://activelivingresearch.org/positional-accuracy-six-portable-gps-receivers https://activelivingresearch.org/positional-accuracy-six-por... [2] https://www.gps.gov/systems/gps/performance/accuracy/ https://www.gps.gov/systems/gps/performance/accuracy/ [3] https://r12.trimble.com/ https://r12.trimble.com/
  • SergeAx 6y ago
    This is an enormously detailed answer, thank you so much!