[time-nuts] Help w/integration problem

John Miles jmiles at pop.net
Wed Jan 4 03:51:25 EST 2006


Thanks to everybody who helped out with this one... it's all working great,
as far as I can tell.  The new release of PN.EXE with the integration
features is here:

http://www.speakeasy.net/~jmiles1/ke5fx/gpib/setup.exe

In addition to all the noise-measurement stuff it did before, it now
measures jitter (both time and phase), carrier/noise ratio, and residual FM.

I'm pretty confident that the math is right... this is the trace I mentioned
comparing to the HP app note:

http://www.speakeasy.net/~jmiles1/pn.gif

(Compare with figure 4 in
http://www.speakeasy.net/~jmiles1/ke5fx/gpib/an270-2.pdf)

The RMS phase jitter that they report is only about 8% less than what I see
on a 24-year-old example of the same analyzer... or less than 1 dB in
carrier/noise terms.  The difference in residual FM is a bit worse than
that, because my trace gets a bit noisier toward the high end of the
500-1000 Hz integration interval, while theirs got quieter.  Still, these
measurements line up to a very-satisfying degree.

-- john, KE5FX





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