Russia installed a radio-jammer that interferes with the signals that direct GPS-guided munitions. Last week, Ukraine blew it up ... with a GPS-guided bomb.
Encryption isn’t really a factor with this type of satellite navigation jamming, at least as far as I’m aware.
Frequency hopping however can be a used as a RF jamming countermeasure, but I’m not sure if that is really for satellite navigation systems.
The frequencies all satnav systems work on are also very specific and known. I would assume that any satnav jammers just jam all RF used by all GNSS constellations at once, but maybe they open up certain bands to allow for their own guided munitions at pre-scheduled times.
Encryption isn’t really a factor with this type of satellite navigation jamming, at least as far as I’m aware.
Frequency hopping however can be a used as a RF jamming countermeasure, but I’m not sure if that is really for satellite navigation systems.
The frequencies all satnav systems work on are also very specific and known. I would assume that any satnav jammers just jam all RF used by all GNSS constellations at once, but maybe they open up certain bands to allow for their own guided munitions at pre-scheduled times.