[time-nuts] Transmitting a time sync signal - what's the trick?

[Hal Murray]

> What's the trick though?  If I send a signal to say "it is 12:33:45",
> by the time that the signal has got there (at a mere 4800bps) and been
> interpreted, it won't be any more. 

The bit rate isn't the problem.  You can easily correct for any constant 
delay.

The problem is noise/jitter.  Do you have a central controller scheduling 
things or do you have etherent/aloha type collisions and retransmissions and 
such to add to the noise?

You can filter out most of the jitter if the receiver has a good local clock.  Just average over several/many samples and maybe discard the outliers.


If you are trying to keep good time on a typical computer, the first step is to calibrate the local crystal.

There is lots of info here: http://www.ntp.org/
(It may be hard to find exactly what you are looking for.)


-- 
These are my opinions, not necessarily my employer's.  I hate spam.