Claude,
I see a jump even smaller than the first one and as I calculated before
(in an answere to Said's mail) this latest jump is much less than the
first one of 550 microHz. I agree with Said that this could be a crystal
jump.
If you want to check the GPSDO's absolute frequency you'd need a second
GPSDO... If you want to check it's stability - how do you know that it's
the GPSDO that jumps? Ok, you see a synchonous jump on the EFC voltage,
that's a good evidence.
If you want to compare the frequency of your 5334B (nice thing, by the
way), the accuracy of your locked GPSDO should be sufficient - the
uncertainty of your locked GPSDO might be in the range of several uHz...
Since GPSDOs make use of highly stable OCXOs to maintain short time
stability (and improve side band noise) it depends on your oscillators,
which one has better stability, the 5334B built-in osc, or the GPSDO
osc. On the picture on ebay I recognize an HP type (most likely 10811)
which is known for it's very good stability performance. I guess it's
not easy to find an oscillator that can beat the 10811.
I use my GPSDOs as external references for my counters and all that
stuff (amateur radio equipment, spectrum analyzer,...) and I'd recommend
that.
>...The receiver is a 6 channels and it outputs two 10 MHz and one PPS.
I think my statement about the osc frequency was a bit unclear. All the
Z38xx have 10 MHz outputs (as far as I know). But the OCXOs inside the
units are different - there are 10 MHz types (HP 10811) (like yours, as
it seems) and 5 MHz types (Symmetricom), which have a doubler to achieve
the 10 MHz.
To cut a long story short, I think, your GPSDO is working fine. With an
antenna seeing some more of the hemisphere it would be working even
better, I think... :-)
Volker
Am 02.03.2013 13:15, schrieb Claude Fender:
Thanks you both for your answers.
I had another jump (positive this time, 24h after the first one) and the efc
curve came back to its previous state, see :
http://uppix.net/f/4/d/c5a277798ca58bb04b41481ece6e7.png.
The receiver is a 6 channels and it outputs two 10 MHz and one PPS.
The antenna has noname and it is installed on a balcony, that's why it has a
poor reception. Sure this is not perfect and I have to improve that.
The log is running every 5 minutes and I didn't notice a holdover mode of the
oscillator.
(I've bought this GPSO to check the frequency of my 5334B for gates times of
60s and 100s. I know I can use the 10MHz of the GPSDO as Frequency Reference
for the 5534B but I wanted to check its frequency first !)
________________________________
De : Volker Esper<[email protected]>
À : [email protected]
Envoyé le : Jeudi 28 février 2013 2h12
Objet : Re: [time-nuts] Z3805A/58503A time receiver : 2 questions
If your unit is exactly like that on ebay 251226027893, it has a 10 MHz HP
oscillator in a double oven, and it's absolutely sure that it's got a 6 channel
receiver.
I should have read before, sorry.
I'm still not sure about your antenna, is it a Garmin? Well, it's most likely
an active type, so what gain does it have? If you installed it on a roof top,
it should see sufficient field strength.
Then do that simple test: disconnect your antenna from the receiver unit and
measure with a multimeter the voltage at the center pin of your N connecter
antenna plug. It has to show 5 Volts, otherwise your antenna can't be working
well.
Volker
Am 28.02.2013 01:26, schrieb Volker Esper:
Hi Claude!
Said says, you should see 6+ sats, I guess he means _at_least_ six. I'm almost
sure, you've got a 6 channel receiver, so you naturally cant't get more than 6
sats at a time.
There are some different models of the Z3805A out there, though they're all
named the same. I've got two units, one with an 8 channel and one with a 16
channel receiver. My 8channel unit never receives more than 6 sats at a time,
never. So I'm shure, it's a 6 channel type...
Maybe I should improve my antenna. But the same antenna provides enough voltage
to receive 12 to 14 sats at once with the 16 channel unit. On the other hand,
my 6/8 channel gizmo very rarely shows less than 6 sats, so, like Said, I too
think, that there is some space for improving your antenna. What antenna do you
have?
One day, while using the 16 channel unit, I experienced the same hops as you
did. All time nuts told me that it had to be a crystal jump. I read about such
phenomenons and all I found was, that the jump in my receiver was too big to
fit to the idea of a crystal jump. Unfortunately my receiver gained fun in
jumping. Now I'm absolutely not sure what it is. Maybe it's a faulty
oscillator. Which one do you have built in? A 5 or a 10 MHz type? I've got a 10
MHz HP and a 5 MHz Symmetricom oscillator.
Cheers
Volker
Am 28.02.2013 00:17, schrieb Claude Fender:
Hello,
This is my first message here although I read this list for a few weeks.
I bought a Z3805A/58503A frequency receiver and I didn't notice on the
pictures that the model number was not written on the front panel. It's not
important but is there a reason for that, if you know ?
The item : http://cgi.ebay.fr/ws/eBayISAPI.dll?ViewItem&item=251226027893
I log some parameters of the receiver and today I notice a "gap" in the
frequency.
Picture : http://uppix.net/e/2/4/cf39ac772e5a69fc616f5cf30f208.png
I have a Rubidium and I measure it's frequency with a 5334B counter locked to the GPS,
and I can see the "gap" too :
http://uppix.net/f/b/a/d86c2737ad135264e4a2b78e503d5.png
measurements are with Gate Time of 10s, 60s and 100s,
Do you know why this happens and how to prevent this behaviour ?
Thanks for yours advices
Claude
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