How would such a device work? Seriously, I've worked on more spacecraft designs than I can count, and I've been personally involved with perhaps a hundred spacecraft that are orbiting right now, and I don't know of any onboard system that could approach the accuracy that GPS gets by using TDOA at multiple well-surveyed ground stations.
What does that have to do with GPS?
Do you know how they measure the altitude of a GPS spacecraft? What the error sources are? Seriously, what conceivable onboard sensor would be more accurate than the GPS approach? 'Cause ranging error is a popular topic in the GPS community, and if you have a better approach than TDOA to multiple well-surveyed sites, we'd love to hear it.
And, for the 3rd time, what is your basis for these statements? Are you simply making them up?
ETA: if you don't know what TDOA stands for (without googling it), you probably shouldn't be making assertions about how GPS works.