[time-nuts] 53230A TIC and TimeLab

Ole Petter Ronningen opronningen at gmail.com
Fri Oct 5 03:16:20 EDT 2018


On Fri, Oct 5, 2018 at 5:08 AM AC0XU (Jim) <James.Schatzman at ac0xu.com>
wrote:

> [...] Since it am especially interested in measuring short-term stability,
> I am going to try using it the method described in  (who??):
>
> http://www.efos3.com/53230A/HPAK53230A-High-speed-TI.html


Thats my website. The method can be a little fiddly if you don't understand
the instrument pretty well, I would suggest getting a bog-standard TI
measurement working first. In either case I'll be happy to assist if you
need some pointers, ofcourse.


> I understand that at some point I will be seeing the noise/stability floor
> of the instrument. According to
>
> http://www.anderswallin.net/2015/04/keysight-53230a-noise-floor-test/
>
> that noise floor may be around 2e-11 at 0.1 sec and 2e-12 at 1 sec.  [...]
>

Well.. I trust I will be corrected if I am wrong, but I believe the
frequency measurements were taken using the "resolution enhanced mode" -
which does not yield the correct ADEV, as shown by the slope on the plots.
See here http://www.anderswallin.net/tag/53230a/ for a followup on that
post by Anders.

A 20ps counter should give a noise floor around 2e-11 at 1 second gate
time, with a slope of -1 on the log-plot; 2e-11 at 1 second, 2e-12 at 10
seconds, 2e-13 at 100 seconds and so forth, untill the noise is no longer
white PM.

Theres a lot more in i.e. Handbook of Frequency Stability Analysis (
https://tf.nist.gov/general/pdf/2220.pdf) and other places -
http://www.leapsecond.com/time-nuts.htm is a good place to start, if you
have not seen it.

Ole


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