FEers have admitted that GPS is a real thing. The claim, however, that it is just some land based system or it uses weather balloons or some such nonsense. But it can be easily shown that GPS is using Satellites. All one needs is a cell phone and a program to show the GPS status. For example, on Android there is a free program 'GPS Status' that will plot all SVs in the sky and the signal strength coming from each SV. The positions of the SVs can be verified to match the orbital predictions on web sites such as
http://www.n2yo.com. The satellite positions repeat daily with a 4 minute delay and they follow a precise path and move much to fast to be a weather balloon.
So at this point the FEer will say something like "Hog wash, the phone can easily know where to plot the positions of the fake satellites". But here is the problem for that argument. If one looks at their phone, they can see what satellites are tracked and which ones are not. And if one is standing in an open area, pretty much all SVs will be tracked. Then they can walk up to the side of a building and see that they loose tracking of all satellites blocked by the building. There is just no way for the phone to be able to fake that information. The signals are coming from the location predicted by orbital parameters, and there is no way a balloon can make that kind of trajectory with that kind of speed and exact repeatability of the position in the sky from day to day.
If you like, I can make a video to show exactly that. Game over, again.