[time-nuts] Thermal impact on OCXO

[Scott Stobbe]

If your DAC spans the full EFC range than 1LSB is 1/2^20 ~ 1 PPM of the EFC
range, and the EFC tuning range is 8/10E6 ~ 1 PPM full scale, so 1 LSB is
~1PPT. So, if everything else is stable the DAC code reflects
changes solely due to the OCXO, which would be an aging of 24 PPT/day.

On Sat, Nov 5, 2016 at 9:57 PM, Bob Stewart <bob at evoria.net> wrote:

> Hi Scott,
>
> The 20 bits span about 6 volts.  The EFC range spans about 8Hz (+/-4Hz).
> I don't do these calculations every day, but that's about 4.5PPT?
>
> Bob
>
> -----------------------------------------------------------------
> AE6RV.com
>
> GFS GPSDO list:
> groups.yahoo.com/neo/groups/GFS-GPSDOs/info
>
>
>
>
> ------------------------------
> *From:* Scott Stobbe <scott.j.stobbe at gmail.com>
> *To:* Bob Stewart <bob at evoria.net>; Discussion of precise time and
> frequency measurement <time-nuts at febo.com>
> *Sent:* Saturday, November 5, 2016 8:38 PM
> *Subject:* Re: [time-nuts] Thermal impact on OCXO
>
> I think that's a nice plot, it looks like you have stepped 160 LSB over 7
> days or roughly 1 LSB per hour. With a 20bit dac you are trimming maybe 1
> ppt/LSB to 4 ppt/LSB? In allan devation terms, the case of 1ppt/LSB, solely
> due to drift, you're at 1E-12 at 3600*sqrt(2) = 5000 s, in the case of
> 4ppt/hour your at 1E-12 at 1280 s. Seems reasonable.
>
> On Sat, Nov 5, 2016 at 2:47 PM, Bob Stewart <bob at evoria.net> wrote:
>
> Oh dear.  I attached the wrong file.  Here's the correct one.
>  ----------------------------- ------------------------------ ------
> AE6RV.com
>
> GFS GPSDO list:
> groups.yahoo.com/neo/groups/ GFS-GPSDOs/info
> <http://groups.yahoo.com/neo/groups/GFS-GPSDOs/info?soc_src=mail&soc_trk=ma>
>
>
>
>
> ______________________________ _________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> <https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts>
> and follow the instructions there.
>
>
>
>
>