[ntp:questions] how do I lock in average frequency correction
cswiger at mac.com
Mon Feb 13 18:59:08 UTC 2012
On Feb 12, 2012, at 11:36 PM, Dave Hart wrote:
>> Agreed, temperature swings will have a major impact on the crystal frequency.
> Well, I know what you're saying but we're talking on the order of 1
> PPM / degree C.
Yeah, on that order. It's noticeable, or can be anyway, but also well within
the tolerances that ntpd will handle just fine.
>> You might be able to improve the stability of the crystal by ensuring good
>> airflow and cooling via HVAC as needed. And I suppose you could adjust the
>> rate by changing the HVAC set-point, but I don't think the benefit is worth it.
>> I'd be more likely switch to an OXCO + GPS on a PCI/PCIe card if such as needed.
> That's OCXO, oven controlled crystal oscillator. Why X for crystal?
> Christ if I know. There's a great article at
> that includes a table of abbreviations you can refer to.
Yes, "OCXO". Electronic schematic diagrams use single or two letter abbreviations, and
"C" was already taken (for "Capacitor"). I seem to recall a crystal is actually "Y" if
using a single letter, or "XO" for two letters....
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