In total agreement, that's why I said it's 'nearly' the speed of light.  At any rate, this is a distraction from the point of my response to the other poster: relaying a GPS signal from another aircraft, etc. is not a suitable solution to jamming.  In order to calculate your position you need at least 4 satellite signals to triangulate your position in 3D.  Without those measurements (i.e. your distance to the satellites) you cannot calculate a position.

 

I think another poster hit the nail on the head re: the solution to jamming: kill the jammers. ;)  It's no different than dealing with enemy attempts to jam regular communications as far as I'm concerned.  At the far end of the capability spectrum, anyone sophisticated enough to have enough air cover to avoid having their jammers killed is probably also capable of just simply killing the GPS satellites.