Yes, it is important. Apparently, you have no idea how GPS works, but simply said your receiver times the distance to several satellites and calculates the position from that. Obviously, if the exact position, including altitude, of the satellites, then your GPS device will not be able to get the correct position.
Hans
Why do you doubt whether i know how the TDOA works ?
The point is that on the one hand you have TDOA measured data, on the other han you can used calculated data, - such as perturbation - SR / GR influence, - gravitational anomalies, - atmospheric collision, - different / angle of space whether impact, - signal delay, - and yes most of the time these 2 sets of data must fit.
And because the 2 sets of data fits, it no reason for calculating such 100 times every day.
I mean are you also digging 100 equal size holes in your garden every day just for fun , only for testing whether the holes all always are the same size ?
No off course not..
In the same way, Why lose time on a job that TDOA very easy can handle..
And this is the point
Even though theoretical calculated data and measured TDOA data, - 500 time has shown no disagreement, - there are still reason to be suspicious.
Polar orbiting satellite can be exceptions. Not all of them very significant, - but if the orbit inclination is close to north relative to ecliptic,- we will sooner or later discover very significant unexpected time dilation anomalies.
No doubt about it.
Off course scientific dedicated satellites, have much larger change, to reveal that.. simply because data can be collected without any interruption, and with full scientific focus.
Exactly therefore some satellites are dedicated to test relativity, - included ISS.
Its like you all agree, that there are no reason to test relativity based on satelittes, - we know everything to 1 millimeter precision right ?..
So why on earth must it be done on board ISS and Galileo 5 & 6 these years ?
Just because it is funny to waste tax payers money ?
Or because we are still not quite sure whether something may be rotten ?