Re: Well timestamps at a µs level...
And the US Military reserve the right (and do) to reduce the accuracy of the GPS system; or even deform the signal - they exercise with this from time to time; and use it when their troops are ‘hot’ as they also have decode for the changes made; so your GPS will be 10s/100s of metres out; theirs will still be spot on (>>1 metre)
I believe that they retained the ability to do this selectively by region. This meant that they could degrade the accuracy of the civilian signal in just the area of the conflict and not everywhere. Clinton told them to turn off this feature known as Selective Availability. The latest generation of satellites - the GPS 3 - don't have (at least publicly admitted to) SA and therefore this can't be used again. There's more here https://www.gps.gov/systems/gps/modernization/sa/data/
Biting the hand that feeds IT
