[time-nuts] simple, cheap clock for the local LAN

Ralph Smith ralph at ralphsmith.org
Tue Apr 6 16:19:33 UTC 2010

On Mon, April 5, 2010 1:18 pm, Mark Sims wrote:
> Just use everybody's favorite GPSDO,  the Thunderbolt.  While it is being
> disciplined by GPS,  it is learning how the oscillator tends to age with
> time and drift with temperature.  If GPS goes away,  it will still
> discipline the oscillator in an "open loop" fashion using its learned
> behavior.  The HP GPSDOs do the same thing.
> Lady Heather has an option for periodically syncing the system clock to
> Tbolt Time.  At its most agressive setting,  it keeps the system clock
> within a windows timer tick (20-50 msec).

I'm not denigrating Lady Heather here, indeed it is a wonderful app. It's
just not the most appropriate tool for this job. Feeding NTP with a GPSDO
meets the requirements of providing time to a network, while providing
carryover. Unless LH has a means of distributing time to other hosts that
I've missed. Also, NTP is capable of providing much closer tracking of
time, with less jitter than the approach used by LH.


More information about the time-nuts mailing list