[time-nuts] TCVCXO Adjustment

David J Taylor david-taylor at blueyonder.co.uk
Fri Apr 13 14:18:39 EDT 2018


Hi

NTP will give you “millisecond" level accuracy / stability. If you want to 
set an
oscillator to 0.1 ppm, you will need to run for over 10,000 seconds. It is 
not
uncommon to have things out in the 10 ms range. That would put you at
100,000 seconds. In more common units, a couple of hours to > 1 day
would be needed.

Keep in mind, this is for a single observation. If you need to make three or 
four
tweaks to get things set, the numbers would go up a bit.

The earlier mentioned GPS approach with a $10 USB dongle would do it a *lot*
faster. More or less, you could expect a bit better than a 1000:1 speed
improvement.

Bob
==================================

With respect, NTP using a GPS/PPS clock can give tens of microseconds or 
better, even on a Raspberry Pi.  For example:

  http://www.satsignal.eu/mrtg/raspi1_ntp.html

(The slight downward slope back over time is an artefact of MRTG with small 
integers.)

Cheers,
Davis
-- 
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor at blueyonder.co.uk
Twitter: @gm8arv 




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