[ntp:questions] Standalone PC Clock Sync
Richard B. Gilbert
rgilbert88 at comcast.net
Sun Nov 4 18:17:56 UTC 2007
Russell, David wrote:
> I have a PC running Windows that gets disconnected from the network for
> up to an hour. I am using NTP to sync the clock while it is connected
> but when disconnected the clock drifts quite a bit. Does anyone have
> any suggestions for how I can maintain the timing in this scenario?
> Also, I have been looking for a PCI card that would give me better clock
> accuracy than the standard Windows clock. Sub-millisecond accuracy
> using NTP is the objective.
> David Russell
You can purchase a PCI card from either Meinberg Funkurhren or
Symmetricomm. Expect to pay $1100 US and up, especially up! These are
equipped with a precision crystal oscillator, optionally an Oven
Controlled Crystal Oscillator (OCXO). They can be equipped with an
optional GPS receiver. The Symmetricomm products are the BC635PCI
and the BC637PCI (with built in GPS). I don't recall what Meinberg
calls their product.
With GPS input, these products can give you sub-microsecond accuracy.
Even without the GPS input they can keep time as accurately as you can
set the clock. They are overkill for most people.
An inexpensive GPS receiver such as the Garmin GPS18LVC ca. $100 US can
do much the same for you if you can site an antenna with an unobstructed
view of the sky. The principal difference is the "holdover" capability
of Symmetricom and Meinberg products; though they are not, in
themselves, primary standards they are extremely good clocks and will
exhibit extremely low drift.
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