[time-nuts] New to Time Synching hardware - needing some advice

Magnus Danielson magnus at rubidium.dyndns.org
Thu Dec 27 23:22:52 UTC 2012

Dear Roy,

On 12/27/2012 06:52 PM, Roy B wrote:
> Hello
> I am new to time synching hardware but have done Linux NTP so I have a little experience in that but I need some advice for a different project.
> I have a PC running Linux that I would like to have on a stable time with roughly 10 millisecond accuracy however this machine is located in a place where it cant get network, GPS, or radio signals.
> Is there something like an Atomic Clock that I could set to the correct time over radio/gps/network and then take this box to the PC?
> Anything that I have looked at just assumes that you have a continuous outside connection from somewhere.

These requirements puzzles me. Why do you need 10 ms accuracy when it is 
not connected to anything? If you have a network connection to it, 
providing NTP timing over it so that whatever time-application in it can 
also interact with the environment where the interaction requires 10 ms 
accuracy counts.

If you have a system where two machines needs to agree within 10 ms, but 
can't be reachable from the outside, just set one of them up as the NTP 
server and the other as slave, and run their own taliban time and be 
done with it.

Point being, do you have absolute timing requirements (to UTC) or 
relative timing requirments (between machines)?

Sometimes when you have isolated machines, the absolute time may not 
need to be very accurate, but the relative timing between them can be. 
Adjusting from wrist-watch every once in a while may suffice for 
absolute time.

So, what is it?

A rubidium may take time to drift off the mark, but for what purpose do 
you take that effort?


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