Seems BS.
The satellites would all be so close in angular separation as seen from the moon as to make the usual GPS location algorithm rather useless. (Signal processing weenies please clear that up). You have to have some appreciable X-Y-Z to establish a fix.
Curiously, last job I had was working on a system to allow lunar explorers to navigate like with GPS. Øbowel killed the return to the moon mission, and I retired in disgust.
We were working on a local lunar surface based system. I was working the RF propagation and reception segment of the idea.
My father Roger Easton invented Timation which was the major predecessor system to GPS. He thought some satellites should be in higher inclinations (GPS has them at 55 degrees) to improve navigation near the poles. Range limitations at Cape Canaveral limit them to 55 degrees. www.gpsdeclassified.com is my website.
I’m an old radio ham. What RF propagation issues are there on the moon? Were they planning on having GPS satellites around the moon? Low orbit? Higher orbit?
It sounds like you would be working with something akin to the long defunct Loran ground based nav signals. Very precise in theory but in practice were affected by the Earth's imperfect magnetic field. It was very long ranged but accuracy was such that it was good for getting your boat to the offshore approach to your landfall when on the water or to the right city when using it in an airplane. Not exactly survey level accuracy! Loran C has been shut down for several decades, replaced by GPS. I understand though that US and European governments are developing a new generation of Loran that will very similar accuracy as GPS. The driver for the new generation Loran is to have a backup to GPS in case the GPS is disabled or degraded.
Whether ground based like Loran or satellite based like GPS, a single data point reading does not give an exact position but a circle of position. You're somewhere along that circumference line but that's all you know. If you have two circles of position and lay them on a chart, the circles overlap a two points. Well, that's not much use as the enclosed area is quite large and thus the +/- error is quite large as well. If you have three circles of position now you're cooking because at your actual position the three intersections are grouped closely together. As a navigator, you would assume you're in the center of the area. In practice a Loran C position would be something like +/- 10 miles. Modern consumer grade GPS is something like +/- 20 feet or so when at it's best. The new generation Loran, if implemented, is supposed to similar accuracy to current GPS.
As others have noted, it's an angle thing related to distance that would make earth satellite GPS not practical. The inherent geometry would be as likely to give a position half way to Mars as somewhere around the moon.
Yeah. It ‘might’ work but the position accuracy would be rather large. If you’re trying to drive around that crater... ooops!
It would also seem that new algorithms would be required in the receivers.