Yes, a lot of GPS receivers provide RAIM or jamming indication, if they detect signals they're not expecting. Gpsjam just isn't set up to accept such data.
I think Galmon.eu may collect it along with all the other receiver-status data, but it isn't exposed in the main dashboard. You'd have to figure out how to extract it from the data, and I don't think anyone's done that yet, but we're in #galileo on OFTC IRC.
The main problem with this approach is that it's hyper-local. Ground stations aren't moving so they don't cover a very broad area, and they're not evenly distributed or even necessarily in interesting locations. Quite the contrary; regimes that employ GPS jamming are likely also hostile to citizens reporting on same.
If you take your own measurements you can do a lot more than what this site is doing, but with the disadvantage that you have to take your own measurements. For example, you could:
1. directly observe signal integrity with your own GPS receiver
2. compare the location your receiver reports with the actual known location
3. compare the location your receiver reports on GPS with the location a different GNSS network reports.
I think Galmon.eu may collect it along with all the other receiver-status data, but it isn't exposed in the main dashboard. You'd have to figure out how to extract it from the data, and I don't think anyone's done that yet, but we're in #galileo on OFTC IRC.
The main problem with this approach is that it's hyper-local. Ground stations aren't moving so they don't cover a very broad area, and they're not evenly distributed or even necessarily in interesting locations. Quite the contrary; regimes that employ GPS jamming are likely also hostile to citizens reporting on same.