Sorry to reply to my own post.
I was wrong on the name of the PocketPC software. It's called Thunderhead see
http://fuzzythinking.com/projects/thunderhead/
Robert G8RPI.
From: Robert Atkinson robert8...@yahoo.co.uk
To: Discussion of precise time and frequency
Been there, done that.
The RFTGm-RB can be disciplined if you connect the pps and the gps data stream
coming from a motorola Oncore.
Regards
Guido
Von Samsung Mobile gesendet
Rex r...@sonic.net hat geschrieben:
I don't think the rubidium module for these systems can be disciplined.
I think
Hi Guido,
Been there, done that.
The RFTGm-RB can be disciplined if you connect the pps and the gps
data stream coming from a motorola Oncore. Regards Guido
I've pulled it apart and the board does show a connection to the EXT C-FIELD.
That trace runs to a jumper labeled A C B and currently C
Hi Everyone,
I'm going to try to calibrate my LPRO 101 to a GPS 1pps signal.
Does anyone know what one turn clockwise of the c field adjustment pot
will do to the signal in terms of ppb ?
Thanks,
Alan
___
time-nuts mailing list --
Hi Alan,
Just did this. Less than 0.005 Hz.
To really fine tune it, you need to used the C-field adjustment pin.
This circuit is simple. A Linear Technology LT1236 precision 5V
regulator and a 10 K linear 20+ turn pot. You can get a sample of the
chip free from Linear Technology.
Hi Brian,
Just did this. Less than 0.005 Hz.
Thank you - was clockwise 0.005 higher or lower?
My Rb is about 0.000731284 fast according to my estimate.
To really fine tune it, you need to used the C-field adjustment pin.
This circuit is simple. A Linear Technology LT1236 precision 5V
Good day all,
I have yet another small oscillator for which I need the pin out. This time the
oscillator is marked Ovenaire Oak Frequency Control and the Model OSC 91-22C
(or maybe G) and the label says it is a Precision Crystal Oscillator so nothing
quite as interesting as a OCXO or even
Hi,
I have designed a very low noise preamplifier that can be used
to characterize regulators etc built around LT1028/AD797 friends
without obscuring their true performance.
The description is at:
http://www.hoffmann-hochfrequenz.de/downloads/lono.pdf
(3.8MB pdf)
regards, Gerhard
I'm converting the code for the VE2ZAZ FLL to a PLL. I'm seeing the phase
correction change the EFC up and down about .02V to .03V over a period of 5
minutes or so (it varies). The full range on the OCXO is about +/- 4Hz varied
by 0 to +6V, so at least this is a tiny value. I feel pretty
Hi
Ok, let's try some math and see if I can do it without blinking this time….
+/-4 Hz for 6 volts is 0.66 Hz / V
output is 10 MHz so 1 Hz is 0.1 ppm
your OCXO is running at 0.066 ppm / V
That's also 66 ppb / V
0.02 V at 66 ppb / V is 0.0132 ppb or 13.2 ppt
The UT+ has a sawtooth output
Hi Bob,
treat your GPSDO like a closed loop control system. If you could
optimize the process itself, e.g. make it's behaviour linear or
eliminate environmental inluences, you should. Then you have to know the
characteristics of your process (the transfer coefficients of the
controlled
Hi
To answer your OCXO question:
The so called 34310-T is a double oven. It should be stable over some range
(say 0 to 70 or -20 to 70) to about 0.1 to 0.5 ppb p-p. Trimble seems to like
+12 on it so one would guess that +12 +/- 5% stable to +/- 0.5% should be fine.
They seem to use it in
Hi Bob,
So, assuming your math is right at .15 ppb, that seems to be within the figures
you gave for the 34310-T.
I'm not attempting sawtooth correction for a number of reasons, the biggest of
which is the uncertainty factor in the PIC. I think I read in the datasheet
that the CCP1 input
Hi again Bob,
D'oh, I think I totally misunderstood your figures in my first response. The
.16ppb is not the frequency accuracy of my GPSDO. It's the amount that I'm
moving the OCXO during a 5 minute timeframe, which is something else entirely.
Like I said I do not have a known good
Hi
If your resolution plus sawtooth is ~ 250 ns, then you have 250 ppb at 1
second. At 300 seconds you would have just under 1 ppb. To get close to the
full range temp stability of the OCXO you would have to run at least 10X that
long. Put another way, the GPS can only stop hurting things past
Hi
With the 5335 you have a measurement with dead time. That makes things a bit
hard to figure out. A much better way to go is to feed a pair of 1 pps signals
into the 5335 and measure their time difference. Unless they are quite close,
you can go for a while with no ambiguity to the reading.
What OS runs on the IPAQ?
Did you have to re-build LH from source?
Edit: OK now I see you are running some other software called
thunderhead. Same questions apply
On Thu, Aug 15, 2013 at 1:17 PM, Robert Atkinson robert8...@yahoo.co.ukwrote:
Hi Chris,
I've posted this before, but it's
Hi
There are two products called IPAQ. One was a desktop computer, the other was a
PDA. The desktop will run anything, the PDA can handle some of the BSD's and
Linux's. Both need to be configured / compiled to match the device.
Bob
On Aug 16, 2013, at 2:44 PM, Chris Albertson
Hi
If my numbers are correct, your DAC is moving the OCXO 0.016 ppb or 16 ppt.
Your 5335 would read that as a last digit flip with a 100 second gate.
For really large numbers on the 5335 it's *much* more convenient to use the
built in math functions. In this case subtract 10 MHz from the
Hi,
This is not my software. See http://fuzzythinking.com/projects/thunderhead/
I just used the complied file, but the source code is there of you want
to change it. The iPAQ I built in was an H2200 series running PocketPC
2002. I've also ran it on a H3900 series (H3950) running PocketPC 2003.
Yes, that was my question, Which did you use, were you able to build LH or
Thunderhead for run on the PDA? If so which OS?
On Fri, Aug 16, 2013 at 12:39 PM, Bob Camp li...@rtty.us wrote:
Hi
There are two products called IPAQ. One was a desktop computer, the other
was a PDA. The desktop
Hi,
To be able to test GPSDO's (and GPS in general) was one of the main reasons
that I made a temp controlled chassis for an LPRO and gave it air pressure
compensation. That was good for tau's of hundreds to tens of thousands of
seconds, and even longer with drift compensation. Add in a
Hi
THe FE's have an interesting approach to temperature compensation. It creates
a broad ADEV hump from about 30 seconds out to several thousand seconds. If you
get lucky your local ambient does not excite the process. It the rest of the
world, you get a goofy hump.
Bob
On Aug 16, 2013, at
I'll figure out something. I'm thinking of icing down my DDS device to put it
at a known temperature so I can do drift comparisons. If not that, there'll be
something else I can try.
On another note: I thought I had destroyed everything when I swapped the UT+
back into the GPSDO.
Hi
Also remember - you need to do a survey on the UT+ and put it into position
hold / timing mode. If you don't you can add a bit more to your error budget.
Bob
On Aug 16, 2013, at 7:58 PM, Bob Stewart b...@evoria.net wrote:
I'll figure out something. I'm thinking of icing down my DDS
I thought I could just re-enter the numbers from the last survey I did. But
either something is wrong or I'm missing something (betting on the latter). I
can't seem to enable TRAIM. I thought I had it setup just like previously, but
under WinCore12 it simply won't turn it on. So, I'm just
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