3 ms·

I assume a working gps is necessary for good signal since orientatiin matters in starlink.

inemesitaffia 3y ago
Starlink can operate in a degraded manner without GPS now
cduzz 3y ago
I'm going to call on Cunningham's law here... (I'm not sure if I am right or wrong but I think I'm right and hopefully someone can correct me) I don't think starlink needs GPS as much as the starlink service is a form of GPS. The base station sees several satellites and the satellites know where they are and so the base station can triangulate where you are, and the whole system requires this precision location mechanism to work, so the 2 way communication is a form of Global Positioning without relying on external GPS data. Perhaps the base station is also able to use GPS but the starlink communication is also able to do exactly what GPS does so "fake GPS" would do nothing to conceal the base station's location and probably make initialization hard or impossible.
- justsomehnguy 3y ago
  Ehm. You need a precise clock for any form of GNSS[0] to function. AFAIR StarLink satellites doesn't have precise clock on the board. And anyway, modern GNSS chips are.. $1? Cheaper? No way you wouldn't use GNSS already deployed and working (and you are not paying for it) in a commercial product. [0] GPS is GNSS, it's just in America GPS became the synonym for GNSS
  - cduzz 3y ago
    So -- for the purposes of locating a base station that's connected to the starlink network -- the starlink network would rely on the base station reporting it's location? Hopefully not... It certainly doesn't need to just trust it when it has direct observation available too. I'm not suggesting that whatever GPSish thing you'd be able to get out of a pure starlink protocol communication would give you super resolution, but it'd certainly be enough to identify "Crimea" vs "Indian Ocean". And as far as base station -> constellation -- putting a GPS receiver in it is of course smart to speed that up, but I'm not sure even that's necessary or just helpful.
  - skissane 3y ago
    > You need a precise clock for any form of GNSS[0] to function How precise? I assume that inaccuracy in the clock produces imprecision in location - how much time inaccuracy produces how much location inaccuracy? > And anyway, modern GNSS chips are.. $1? Cheaper? No way you wouldn't use GNSS already deployed and working (and you are not paying for it) in a commercial product. Rather than using the Starlink satellites as an alternative to GPS - get a location fix using both Starlink and GPS, and compare them. Even given the former is going to be significantly less accurate - suppose GPS is accurate to within 5 metres and Starlink is accurate to within 5000 metres - well, if the two differ by 50,000 metres, you know something is going wrong, and the terminal might decide to disable itself in such a situation.
    - justsomehnguy 3y ago
      > How precise GNSS satellites orbits are between 20000km and 30000km. 20kkm is 0.06671s of c, 30kkm is 0.10007s, 5km is 0.000016678. So a very precise, that's why they have an atomic clock on board instead of cheap quartz one. > if the two differ by 50,000 metres, you know something is going wrong Like what your imprecise methods give you a very rough estimate where is the terminal and your legitimate customers in the nearby areas (not even doing anything for or against) are saying thanks for their shut off terminals. https://upload.wikimedia.org/wikipedia/commons/b/b4/Comparison_satellite_navigation_orbits.svg https://upload.wikimedia.org/wikipedia/commons/b/b4/Comparis... https://www.omnicalculator.com/physics/light-year https://www.omnicalculator.com/physics/light-year

Starlink can operate in a degraded manner without GPS now

I'm going to call on Cunningham's law here... (I'm not sure if I am right or wrong but I think I'm right and hopefully someone can correct me) I don't think starlink needs GPS as much as the starlink service is a form of GPS. The base station sees several satellites and the satellites know where they are and so the base station can triangulate where you are, and the whole system requires this precision location mechanism to work, so the 2 way communication is a form of Global Positioning without relying on external GPS data. Perhaps the base station is also able to use GPS but the starlink communication is also able to do exactly what GPS does so "fake GPS" would do nothing to conceal the base station's location and probably make initialization hard or impossible.

justsomehnguy 3y ago
Ehm. You need a precise clock for any form of GNSS[0] to function. AFAIR StarLink satellites doesn't have precise clock on the board. And anyway, modern GNSS chips are.. $1? Cheaper? No way you wouldn't use GNSS already deployed and working (and you are not paying for it) in a commercial product. [0] GPS is GNSS, it's just in America GPS became the synonym for GNSS
- cduzz 3y ago
  So -- for the purposes of locating a base station that's connected to the starlink network -- the starlink network would rely on the base station reporting it's location? Hopefully not... It certainly doesn't need to just trust it when it has direct observation available too. I'm not suggesting that whatever GPSish thing you'd be able to get out of a pure starlink protocol communication would give you super resolution, but it'd certainly be enough to identify "Crimea" vs "Indian Ocean". And as far as base station -> constellation -- putting a GPS receiver in it is of course smart to speed that up, but I'm not sure even that's necessary or just helpful.
- skissane 3y ago
  > You need a precise clock for any form of GNSS[0] to function How precise? I assume that inaccuracy in the clock produces imprecision in location - how much time inaccuracy produces how much location inaccuracy? > And anyway, modern GNSS chips are.. $1? Cheaper? No way you wouldn't use GNSS already deployed and working (and you are not paying for it) in a commercial product. Rather than using the Starlink satellites as an alternative to GPS - get a location fix using both Starlink and GPS, and compare them. Even given the former is going to be significantly less accurate - suppose GPS is accurate to within 5 metres and Starlink is accurate to within 5000 metres - well, if the two differ by 50,000 metres, you know something is going wrong, and the terminal might decide to disable itself in such a situation.
  - justsomehnguy 3y ago
    > How precise GNSS satellites orbits are between 20000km and 30000km. 20kkm is 0.06671s of c, 30kkm is 0.10007s, 5km is 0.000016678. So a very precise, that's why they have an atomic clock on board instead of cheap quartz one. > if the two differ by 50,000 metres, you know something is going wrong Like what your imprecise methods give you a very rough estimate where is the terminal and your legitimate customers in the nearby areas (not even doing anything for or against) are saying thanks for their shut off terminals. https://upload.wikimedia.org/wikipedia/commons/b/b4/Comparison_satellite_navigation_orbits.svg https://upload.wikimedia.org/wikipedia/commons/b/b4/Comparis... https://www.omnicalculator.com/physics/light-year https://www.omnicalculator.com/physics/light-year