[time-nuts] tcxo

folkert folkert at vanheusden.com
Thu Dec 11 09:31:32 EST 2014


> Some of the Arduinos (not sure about Mini 04 but I am suspicious) use
> ceramic resonators rather than real crystals and thus may have extremely
> poor frequency stability. See here
> http://jorisvr.nl/arduino_frequency.html
> for an example.

ah!
Very intriguing material, those crystals. I wonder what happens in them
that they start to tick(?) at precisely 16MHz for example.

> Is there some reason you are using a 16.9344 MHz oscillator rather than
> 16.0? The processor will probably work, but timing of Arduino functions
> like millis() and software serial baud rates will be affected.

Misread I guess :-|
Like that time that I bought 20 max690 instead of max680 ics. sigh.

> On Wed, Dec 10, 2014 at 2:19 PM, folkert <folkert at vanheusden.com> wrote:
> 
> > > I'm experimenting a bit with time keeping.
> > > For that I use cheap low power hardware like raspberry pies and
> > > arduinos.
> >
> > Hi people,
> >
> > Thanks for all the replies! Took a bit to respond but I had the flu.
> >
> > My objective is, to get the best precision/accuracy possible with said
> > hardware.
> >
> > The first step is preparing an arduino. I found one that has an easy to
> > desolder crystal:
> >
> > http://upload.wikimedia.org/wikipedia/commons/thumb/0/04/Arduino_Mini.jpg/170px-Arduino_Mini.jpg
> > Bought a couple of those and some of these:
> >
> > http://www.aliexpress.com/item/Precision-TCXO-square-wave-oscillator-TCXO-16-9344MHz-line-rectangle/1104200137.html
> >
> > While waiting for these and the parts for the schematics, I'm toying
> > around with implementing ntp servers (well, sntp) for arduino. With
> > lots of blinkenlights of course and with ethernet. Not trivial I can
> > say.
> > This is the jitter plot of a test where time is fed from an RTC module.
> > I did not plot the drift but it is +/- 120 seconds in the 3.8 days I
> > measured it.
> > http://vps001.vanheusden.com/~folkert/aRTC.png
> >
> >
> > Folkert van Heusden
> >
> > --
> > ----------------------------------------------------------------------
> > Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.com
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> 
> 
> 
> -- 
> 
> --Jim Harman
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Folkert van Heusden

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