[time-nuts] Is my Cs C-Field set OK or do I need to take more data?

[Poul-Henning Kamp]

In message <41E22178.4020103 at pacific.net>, Brooke Clarke writes:
>Hi Poul:
>
>Ha    ha    ha   you give me a chuckle.  Probably because that's the 
>problem, when to stop and change something.
>I'm thinking I might be able to keep this test going and at the same 
>time get a GPS direct 1 PPS for comparison.  I think the PRS10 is adding 
>a variable that actually makes the test harder than it needs to be.  I 
>was hoping that the PRS10 would act as a flywheel to smooth out the GPS, 
>but I think it's more like a roller coaster.  After posting the plot and 
>watching a movie the data went back down to the 32 ns area and so the 
>data has taken on a completely new flavor.

Running the PRS10 off a GPS is not as trivial as it could sound.  If your
GPS has significant jitter (they all do) you need to run with the 256
sample averaging filter ON in the PRS10.  If you do that, the entire PLL
changes dynamics significantly and at least I have found that a relatively
short timeconstant is necessary (I'm using a UT+ and PT=8)

Poul-Henning

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