I've never seen noise generators used as GPS jammers, that would be hugely inefficient. All boards I've seen so far, although not emitting a single frequency, jammed the target using sweep generators operating on the desired GPS frequencies. Some even do that simultaneously, which is why they use multiple antennas; if they transmitted noise they could do that using a single noise generator and a wide band antenna.

Example: http://jammergroup.quality.chinacsw.com/pz66df87e-handheld-6...

And by the way, Boeing had jamming resistant GPS back in 1998.

https://boeing.mediaroom.com/1998-04-23-Boeing-Anti-Jam-GPS-...