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.
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.