3 ms·
FWIW, that particular problem isn't likely going to be an issue for Starlink. Starlink satellites orbit at 550km vs. 20000km for GPS. The transmission is much
by ajross 4y ago
FWIW, that particular problem isn't likely going to be an issue for Starlink. Starlink satellites orbit at 550km vs. 20000km for GPS. The transmission is much (much) closer to a straight line approximation and ionosphere refraction is negligible.
In fact, the line of sight transmission to and from a Starlink satellite is likely to be significantly better than that between an airliner and its local WAAS station, which is confounded by ground reflections. (Edit for clarity: WAAS is just digital data, this isn't an actual error in the signal. The point is more "you have to spend more engineering effort on the transmission environment of the correction signal for GPS than you do on the actual signal for Starlink")
- brandmeyer 4y agoAlmost all of the ionosphere's total thickness is below 550km, so the lower altitude doesn't matter. Starlink sees less impact from the ionosphere because the carrier frequencies are higher, and dispersion is proportional to 1/f^2.
- ajross 4y agoI don't think that's true? Plasma density goes up with altitude out to quite some distance, though it's nonlinear. And in any case it's a refractive thing. Having a somewhat lower index doesn't make much difference when one lens is 40x thicker than another.
- m463 4y agoI would imagine many more satellites to choose from. (I'm uncertain, lower orbit might give you more satellites, but I don't know how many would be in view - many more or fewer)