[time-nuts] HP Z3801A Question
SAIDJACK at aol.com
SAIDJACK at aol.com
Thu Nov 13 21:41:13 UTC 2008
Hello Ernie,
as Bjoern mentioned I think the HP is indicating Time Interval between GPS
and OCXO 1PPS in nanoseconds, while the Fury is indicating estimated frequency
accuracy, a unitless number.
The Fury is showing estimated average frequency error over the last 1000
seconds, similar to AVAR 1000s.
You can run GPScon on Fury too, and should be able to compare against the
graphic you did for the HP unit.
Or you could set the LCD of the Fury to show Time Interval to UTC, or probe
this time interval to UTC with the command ptim:tint? that will return the
offset in nanoseconds as well.
An offset of +/-50ns to UTC seems to be normal for the HP unit. On the Fury,
I would expect this to be +/-10ns on a good OCXO.
To the benefit of the Z3801A unit: if the HP unit indicates a larger offset,
it may also be because it's internal GPS is not as good as the Fury GPSDO
receiver. It does not necessarily mean the OCXO is causing the error, it could
be that the HP GPS is causing the error, and the HP OCXO is still dead-on
because it filters out its higher GPS errors.
bye,
Said
In a message dated 11/13/2008 02:45:57 Pacific Standard Time,
ernieperes at aol.com writes:
And running parallel the FURY board with a TEMEX OCXO and displays
+1,6E-10 is the average very often 10E-11 and sometimes for a relative
short time / 4-5 min / 1,4E-12.
Any idea why the Z3801A not displaying better figure?? Something wrong
with the HP unit????
Thanks Ernie.
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