I thought GPS signals from space were incredibly weak. Limited power budget + 100km in the sky. Seems trivial for a ground based system to crank up the watts to whatever arbitrary limit they desire.
True, signal per satellite is only around 150-160dBW on earth despite them radiating at 25W. Satellites are ~20000km away. If a jammer is 100 times closer (200km), they need to use only 1/10,000 (1/100^2) the power, so it's very easy to jam sadly.
