>>Is the DoD not subject to FCC regulation?

That is complex, but most likely no. Like the FAA they largely respect the civilian agencies but ultimately they exist outside of that civilian regulation

>>Are there multiple bands that different types of GPS signals use (civilian vs military)?

Yes the military GPS is different from the Civilian GPS, the US DOD has the ability in a time of war to cut off Civilian access to the GPS Network where only US military (and approved Allies) receivers will work. This is one (of many) reasons the EU, Russia and China all have their own GPS systems

>>How could any sane human approve an interference with this traffic?

While I do not know if I agree (have not read enough on the interference to form a definitive opinion) the supporters of the new network claim there will not be any meaningful interference, that the DoD is over reacting and if there is Interference they will be required to replace the equipment..

> >Is the DoD not subject to FCC regulation?

> That is complex, but most likely no. Like the FAA they largely respect the civilian agencies but ultimately they exist outside of that civilian regulation

Indeed, the DOD can do pretty much what they like regardless of what the FCC says. Of course, it all works better if everybody stays in their own sandbox, so the DOD does, by-and-large.

In general, government frequency allocations and usage are coordinated by the NTIA Office of Spectrum Management. But here again, the NTIA OSM negotiates with the DOD, they can't enforce anything on the DOD.

> the military GPS is different from the Civilian GPS

I remember reading at some point that the civilian GPS was randomly offset so as not to give extremely accurate coordinates like the military GPS does. I thought that was interesting, if true.

The US used to intentionally degrade GPS signals available to civilian receivers as compared with those available to military ones, but it stopped doing that in the 1990s.

The biggest difference now between military and civilian GPS is that military receivers use two frequencies, whereas most civilian ones only use one (since using two costs more).

For many years the government intentionally degraded the quality of GPS signals available to civilians. Look up "Selective Availability" - it was stopped in 2000, at which point consumer GPS became viable.

The FCC does not have regulatory authority over DoD.

>How could any sane human approve an interference with this traffic?

If there is a business application with a powerful enough lobbyist and/or large enough political contribution chest, then of course they should be given approval.