[time-nuts] KS problem

Adrian rfnuts at arcor.de
Wed Dec 10 15:54:56 EST 2014


Bob,

please describe your test setup more detailed.
There are a few points that I don't understand.
A phase difference of 6000 ns (600 ns times 10 as by the scaling of your
plot) between two 10 Mhz signals doesn't seem to make sense to me. That
would be 6 full periods of a 10 MHz signal.
And, when you have the homegrown unit connected to input 1 (start), and
the KS to input 2 (stop), how does it compare to the PRS45?
Or, do you mean something different with 'triggering'?
As by my understanding, a TI counter is triggered by the input signal at
the start input, which is usually input 1, and keeps counting time
interval until the signal at input 2 (stop input) stops it.

Adrian

Bob Stewart schrieb:
> I've been uncomfortable with this KS since I got it; even having to return the REF-0 unit for comms problems.  Now that I have the PRS45A, I think I've proved that the KS does have a problem.  Has anyone else had something like this plot shows?  Any idea what's causing it?  I'm not seeing anything like this on my home-grown unit, but that uses an LEA-6T instead of a UT+.
> This plot is the phase difference between the 10MHz from the KS vs the 10MHz from the PRS45A.  The 1PPS from my homegrown unit is being used to trigger the 5335A which is measuring the time interval.  I could switch the trigger to the KS, but I don't think that would change anything, since it's the phase between two 10MHz signals that's being measured.  Or do I misunderstand how the 5335A triggering works for TI measurements?  I can post the setup commands for the HPIB if wanted, or even my somewhat convoluted logging program.
>
> http://evoria.net/AE6RV/KS/fll.png
>
> Bob - AE6RV
>
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