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

Ralph Smith ralph at ralphsmith.org
Tue Apr 6 12:19:33 EDT 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.


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