[time-nuts] Holdover: Z3801A vs KS-24361
kb8tq at n1k.org
Sun Apr 15 10:01:37 EDT 2018
There isn’t much you can really see on a GPSDO comparing it to a normal OCXO.
The OCXO simply is not accurate enough. You need something like a Cs standard,
a different GPSDO, or a good Rb for the reference. (Yes, if you have a hydrogen
maser, you *can* use that ….).
First thing to check is the DAC readings on the unit ….
> On Apr 15, 2018, at 6:59 AM, Hal Murray <hmurray at megapathdsl.net> wrote:
> kb8tq at n1k.org said:
>>> A KS-24361 says:
>>> Predict 394.1 us/initial 24 hrs
>> That would suggest the unit is unlocked. It should be below 10 us. Just as
>> with the 3801, the estimate is a bit fuzzy. You should be able to see issues
>> in the data on the Z3809/Z3810.
> It says it is locked and has been locked for days.
>>> Locked to GPS TFOM 3 FFOM 0
> I used this as a learning exercise for my new TICC. Something is clearly
> The reference for the TICC is the crystal in a HP 5334B with the good-crystal
> option. It's not calibrated, but there isn't any GPS logic to jerk it
> around. I assume the swing is due to temperature. I corrected the slope of
> the graph by hand.
> Here is a day+ of data:
> Here is a zoomed in chunk:
> These are my opinions. I hate spam.
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