Re: Deviations of satellites from their orbits

On 16 Apr, 23:28, Junoexpress <MTBrenne...@xxxxxxxxx> wrote:
Hi,

I am wondering if anyone can provide a rough estimate for what the
error in the satellite orbits typically is. To be more precise, we
know that the satellite orbits are in principle "well-defined", i.e.
they are supposed to lie in defined planes and are supposed to have
such-and-such a spacing for the satellites in the same plane, etc,
etc. I've been told by people in GPS community however that the
satellites have non-trivial deviations from their "expected"
positions.
Does anyone now if these deviations of the satellites from their
expected orbits can be described and does anyone have a ballpark idea
as to their magnitude?

I try to answer. As far as I know, orbits are affected by few meter of
error in the satellite position.
It's possible to do better predictions and use more complex orbits
equation to reduce the error, but unfortunaly those equation does not
fit in the GPS nav message...
JPL for example is able to predict satellites position very
accurately, much more than the broadcasted ephemeris may do (because
they can't describe the full model), using a very complex model that
takes into account many known paramenters.
So, to answer to your last question: deviations can be modeled and
described and the magnitude of the error is few meters (sorry, I don't
have more precise value for this, but should reasonable). Of course
even the most complex model won't be perfect...

Claudio
www.claudegps.altervista.org
.

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