[time-nuts] Z3801 Newbie Question
Artek Manuals
Manuals at ArtekManuals.com
Thu Jan 28 16:49:02 UTC 2016
OK
My Z3801A came out of mothballs after 15 years in controlled storage and
appears to be behaving. now I am curious as to what I am seeing
First I am not truly a "time" nut ( I am semi retired and have not worn
a watch since October 12th 2008 :-) ). I am probably more of "frequency"
nut . I use the Z3801A as my 10MHz reference. Having a reference source
that is good to .1Hz at 10MHz is more than adequate as a reference for
my counters, signal generators and and spectrum analyzers. But like all
engineers if you give me the numbers I an drawn to trying to figure out
what they are telling me.
My Z3801A has been on for about 2 weeks now and typically reports 1PPS
+/- 20ns readings 20 hours/day. Then all of a sudden once or twice a day
it will go nuts and the variation increases to +/- 80ns for an hour or
two before settling back down. Watching the 10mhz on a 10 digit counter
shows no short term change in the frequency of the OCXO when the thing
goes nuts there are slight changes in EFC but nothing dramatic vs any
other hour to hour variation. The Allen and modified Allen deviation is
around 2e-13 as it approaches 1e5 samples
Here is the setup
1) Z3801A
2) Symmetricom 58532A antenna, just above the roof, with 8 feet of RG213
to the Z3801A
3) Running on a lab grade power supply at 48.5 volts (voltage variation
over time is less .05 volts)
4) Lab runs at 73deg F +/- 2 degrees , humidity is NOT closely controlled
5) Running Z38xx software
6) Elevation cutoff on satellites is set for 15 degrees
And here is the question is the sudden jump in the pps deviation due to
ionospheric and the satellite constellation change? IS there anything I
can do to minimize it (or is it even necessary to worry/ wonder about)
This behavior has going on since the beginning so it is not likely
related to events earlier in the week. But that set me to wondering
could I minimize it by say raising the elevation mask? Are there
satellites in the constellation that are notorious for noise etc that
could be excluded from the tracking list ...etc etc
Dave
NR1DX
ArtekManuals.com
A man with a watch always knows what time it is
A man with two watches is never quite sure
--
Dave
Manuals at ArtekManuals.com
www.ArtekManuals.com
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