[time-nuts] Z3801A performance plots
John Ackermann N8UR
jra at febo.com
Fri Jan 25 17:37:04 EST 2008
Very nice. Thanks! (I'll report when I have my holdover experiment
finished in a few days.)
Tom Van Baak said the following on 01/25/2008 05:34 PM:
>> Tom's plots at http://www.leapsecond.com/pages/z3801a-osc/ show 13
>> Z3801As running in unlocked mode, measured against one of his most
>> excellent references. So I think that plot shows what you're looking
>> for. I was just trying to show what you get when you are running in the
>> normal locked condition (my units almost never go into holdover, so I
>> was more interested in what the normal behavior was).
>> One thing that's not clear from Tom's page, though, is whether the units
>> were in "smart" holdover mode (ie, no GPS signal but the CPU still
>> steering based on its learned aging curve) or truly freestanding with no
>> EFC being applied.
> I'm pretty sure those Z3801A were in factory reset mode when
> I made the stability measurements. For that experiment I was
> only interested in short-term stability; a range of tau where the
> smart ageing correction has little or no effect.
> You also asked about z3801a free-run vs. GPS locked plots. I
> found old data for GPSDO #4 (of the 13 I tested in 2002).
> Free-run stability for #4.
> GPS locked stability for #4:
> Here I put the two runs in color on the same plot:
> Between the three plots you get a good feel for the function
> of a GPSDO.
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