Haven't looked into this in depth but sub-nanosecond sync for systems up to 10km apart is interesting since 10km is about 33 light microseconds. There is some trickery going on.
UltraSane•32m ago
Yes, it uses phased locked loops and measures phase difference between the master clock and the local clock.
elromulous•9m ago
It's totally possible to achieve synchronization better than light transmission time. For the purposes of synchronization, the speed of light delay, and any other delay are indistinguishable, and need not be distinguished.
skulk•43m ago
UltraSane•32m ago
elromulous•9m ago