Hi Tim,
Thanks for the document. I have been doing some 12 hour holdover tests. But
as I mentioned, the HP quick projections had fooled me into thinking there was
some trick to this other than actually capturing the DAC over multiple days to
get a real projection.
Bob
-----------------------------------------------------------------
AE6RV.com
GFS GPSDO list:
groups.yahoo.com/neo/groups/GFS-GPSDOs/info
From: Tim Shoppa <[email protected]>
To: Bob Stewart <[email protected]>; Discussion of precise time and frequency
measurement <[email protected]>
Sent: Thursday, October 6, 2016 12:37 PM
Subject: Re: [time-nuts] Measure GPSDO stability with minimum resources?
The HP Smartclock app note will help you a lot:
http://leapsecond.com/hpan/an1279.pdf
There are lots of Z3801A EFC curves on the web for you to see what typical
range of unit-to-unit variation is.
Of course to actually test holdover, you do that by opening the PLL loop
(unhook GPS antenna) and letting the EFC extrapolation in your software run for
a day (or whatever), watching the phase difference. Then you have to test that
the system recovers back into phase lock smoothly after getting hooked back up.
Tim N3QE
On Wed, Oct 5, 2016 at 1:37 PM, Bob Stewart <[email protected]> wrote:
For my GPSDO, I need to calculate the OCXO aging for holdover projection
purposes as well as get some figure of merit for the recent past of the OCXO
stability. The latter is so that I can determine that the PLL has (or soon
will have) a good lock. I'm developing on a dfPIC33FJ128MC802, and I've used
about 70% of the code space, I could probably set aside 4K bytes of data space
for this calculation.
I have a rather primitive way of doing part of this, but I was hoping someone
would steer me to something a bit better.
Bob
______________________________ _________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to https://www.febo.com/cgi-bin/ mailman/listinfo/time-nuts
and follow the instructions there.
_______________________________________________
time-nuts mailing list -- [email protected]
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
