[time-nuts] sync computer clock ticks

Bruce Griffiths bruce.griffiths at xtra.co.nz
Thu Jan 3 22:25:31 EST 2008

Michael Di Domenico wrote:
> This has probably been asked many times before, but i am unable to
> find any documentation to point me in the right direction.  And yes i
> am a newbie with clocks...
> I'd like to synchronize the clock ticks on 16 different computers
> running linux, down to the 1usec area.  Is this even possible from a
> computer hardware standpoint?
> If so, can someone point me towards some documentation that explains
> how to wire up 16 computers to a reference clock source and override
> the computer internal clocks?
> I found the Symetricom website, but it seems light on details on
> exactly how a solution like this all connects together and they're
> products are likely outside my budget.
> Ideally, I'd like to use the serial port on each of these 16 servers
> to connect to some device to get the synchronization signal from a
> reference.  Even if this was possible, i don't think it would get me
> to 1usec though.
> Thanks
> - Michael

Google ntp.

It is unlikely that you will synchronise the computer clocks to within
1us with ntp unless the computer hardware and operating system is
suitably modified.
This can be done cheaply (one machine needs to be setup as a dedicated
stratum 1 ntp server synchronised to a good time source like a M12M gps
timing receiver or equivalent device).
NTP broadcasts the required info as LAN packets.

If you really need that precisionyou may need to use ptp with suitable
hardware (National Instruments and others have suitable boards)
NIST has a webpage on PTP.


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