Hi All,
I have now redone the original experiment (same settings), and this time
round no jumps at all. Strange. This means I cannot reproduce what I
originally measured, making it all the more difficult to hunt down the
issue with certainty.
Thank you for the good advice thus far. For future
I'm now wading through the GPS data I logged to see if anything happened at
the time of the jumps. Will post once I find something.
On 29 November 2013 15:35, Stephan Sandenbergh ssandenbe...@gmail.comwrote:
Hi All,
I have now redone the original experiment (same settings), and this time
Hi,
Ok, the 53131A trigger settings: I've turned auto trigger off and set it to
trigger at 2V (I think this is right, but I'll have to go and double check
the exact threshold setting) threshold. Sensitivity is set to high.
Location is GPS surveyed and all M12+'s are set to position hold mode.
I
Hi
Something is going wrong somewhere. The question is where. Three ideas /
targets here:
The counter is a 100 ns (10 MHz input) beast, so it *might* be the issue.
The offset source or the GPS might also be the issue (thus avoiding 1/10.24
MHz).
The idea with the larger offset is that
Hi,
I'm using three Motorola GPS Timing 2000 Antennas. They are co-located on
the roof of our building with a clear view of the skies. The view is almost
360deg but a mountain is blocking off a small bit of it to the South-East
side. I'd assume some multipath is possible, but I'd thought that the
Hi Stephan,
Using a single antenna and splitting it is an idea, but then I still need
to devise something to inject the antenna DC power at the other end of the
splitter etc. And, we are trying to measure the relative offset between
the
antenna/receiver pairs for calibration.
Most generic
Below is a plot so you could see exactly what I measured. What is peculiar
is that the time jumps by exactly 100ns to 200ns. Almost as if the GPS
receiver decides to offset the time by twice the amount I set it to. Which
is why I initially thought it might be a firmware thing. I suppose
Hi
The counter and offset generator both should be quite accurate at a 1 us
offset. That’s large enough that you are outside the range of most GPS jumps.
If you are going to move things around, you might as well move out to that
vicinity.
Bob
On Nov 21, 2013, at 6:20 AM, Tom Van Baak
Yes, do not use tiny offsets, go to 1us: I use microseconds offsets to
take PPSes measurements .
On Thu, Nov 21, 2013 at 1:34 PM, Bob Camp li...@rtty.us wrote:
Hi
The counter and offset generator both should be quite accurate at a 1 us
offset. That’s large enough that you are outside the
The 100ns is exactly one cycle at 10 MHz. GPS receivers use this, or
something very close, as an internal clock.
Joe,
The vintage Oncore VP used a 9.54 MHz clock (which is why its sawtooth is about
+/- 52 ns).
Stephan is using the newer M12+T (~40 MHz clock, which is why its sawtooth is
Subject: Re: [time-nuts] Strange 100ns jumps on Motorola M12+T
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Hi,
I'm using three Motorola GPS Timing 2000 Antennas. They are co-located on
the roof of our building
Hi
To be clear - the idea of going to a non-100 ns multiple is a good one. You
probably should avoid multiples of 1/10.24 MHz as well.
Bob
On Nov 21, 2013, at 8:00 AM, Azelio Boriani azelio.bori...@screen.it wrote:
Yes, do not use tiny offsets, go to 1us: I use microseconds offsets to
take
On Thu, Nov 21, 2013 at 12:49 AM, Stephan Sandenbergh
ssandenbe...@gmail.com wrote:
...
Using a single antenna and splitting it is an idea, but then I still need
to devise something to inject the antenna DC power at the other end of the
splitter etc. And, we are trying to measure the relative
Hi,
Bjorn, it is good to know such splitter devices exist. This is really neat.
I'm using the built-in offset function of the M12+, and not an offset
generator. I'm currently redoing the measurement to see if it has similar
issues. And yes, I was also interested to see what would happen at other
Hi,
I've recently measured the 1PPS outputs of three Motorola M12+T GPS
receivers using two HP53131A TICs. Antennas are located next to one another.
Now I notice the one M12+T has changed its time offset by 100ns three times
over the period of 48hrs. The jitter remains the same, only the offset
Subject: [time-nuts] Strange 100ns jumps on Motorola M12+T
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Hi,
I've recently measured the 1PPS outputs of three Motorola M12+T GPS
receivers using two HP53131A TICs
One M12+ is the reference and the others are DUTs? Three times but in
one direction only for a 300ns total or what? The offset returned to
0? Please, detail better what happened.
On Tue, Nov 19, 2013 at 12:17 PM, Stephan Sandenbergh
ssandenbe...@gmail.com wrote:
Hi,
I've recently measured the
Two antennas near each other? Could they interact under some conditions?
Could you be seeing multi path in some satellite geometries?
Try spacing them apart or BETTER get a splitter and use only one antenna
but take the second antenna an far away, I wonder if it is acting like a
reflector or
Stephan:
This sounds like some kind of antenna placement issue.
What is your Latitude?
Can you describe your antenna systems?
Best case: Antennas above all nearby reflecting objects/buildings/trees,
clear
view of the sky for 360 degrees,
Worst case: Indoors, patch antenna on the window
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