Fun fact, the Galileo system was designed to be more accurate and difficult to jam than the civilian GPS but after the US saw this a potential threat and considered shooting down the satellites in case of a global conflict, the design was switched to a frequency they could easily jam.[1] [1] https://en.wikipedia.org/wiki/Galileo_(satellite_navigation)...
What makes a frequency easy to jam?
> At issue is the U.S. Department of Defense (DoD) desire to be able to jam other radionavigation signals in a theater of operation so as to provide an edge to allied users of military GPS receivers. This "selective denial" capability would be complicated by the presence of an encrypted PRS signal atop the M-code bands, because the U.S. could not jam the PRS without jamming its own signals.
There's some more info here: https://arquivo.pt/wayback/20090628141907/http://findarticle...