Standard Frequencies

[ppppenguin]

When you're using a transmitter which sends time signals (as against just a standard frequency) then remember that each kilometre from the TX is about a 3us delay. If you know your location you can in theory allow for that. if you really need that level of absolute timekeeping. Frequency accuracy is of course unaffected.

I am still amazed by PTP (Precision Time Protocol) which allows sub microsecond timekeeping over TCP/IP netwroks whose delay isn't very predictable.
https://en.wikipedia.org/wiki/Precision_Time_Protocol

One application of PTP, not yet widespread, is the synchronisation of TV systems. Unlike PAL or NTSC which need nanosecond accuracy genlock between sources for accurate switching etc, digital TV is happy with microseconds of error since all inputs to studio equipment have at least a 1 TV line buffer.