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<div class="moz-cite-prefix">Hi Caleb!<br>
<br>
The list must be feeling under the weather if I'm the first person
to reply to you. :P There's been a lot more chatter recently on
freenode/#HamWAN. Feel free to come in and idle if nothing else.<br>
<br>
So we had the Tuesday meeting (you should dial in if you can,
details on front page of hamwan.org) and gave some thought to what
might be up your alley. One of the things we're trying to do is
to improve our lab capabilities in terms of antenna radiation
measurement. Right now we can take 1-dimensional slices of these
patterns and produce results like this:<br>
<br>
<div align="center"><img
src="cid:part1.09000902.04080001@bartk.us" class="fixedSize"
alt="./temp/cache/6daf471697293d9e55e0b9a31e79da09_1.png"><br>
</div>
<br>
You can tell from the above that this particular antenna is fairly
well behaved, nice even power spread over a 120 degree front
beamwidth, and reasonable sidelobes towards the rear.<br>
<br>
But 1D scans don't tell the whole story. So we bought some
hardware to control antenna movement in 2 rotational dimensions.
When this hardware is guided properly, along with the signal
measurement equipment, we could generate full blown 3D radiation
pattern images like this:<br>
<br>
<div align="center"><img class="decoded"
alt="http://www.antenna-theory.com/antennas/reflectors/dish3.jpg"
src="cid:part2.08060001.09090106@bartk.us"><br>
</div>
<br>
You can see so much more detail here, since it shows exactly what
happens at all possible radiation angles in our 3D universe. One
more dimension could be added to this though, and that is
frequency. It would be good to see how these 3D patterns change
shape as the antennas are swept through their operational
frequency range. We could also look at characterizing
polarization as yet another dimension.<br>
<br>
So, long story short, the guy who's been tinkering with getting
all the control software written for running these measurements
has been swamped for time. Perhaps with your CS background you
wouldn't find it too difficult to help bring this measurement
setup into reality? Here's what's needed:<br>
<br>
1) 2-axis control commands need to be sent over a serial port.
Timing and synchronization and reproducibility are considerations
here, so it's not entirely arbitrary how this is done.<br>
2) Commands need to be sent to possibly multiple microwave
instruments over a GPIB interface. At the very least, commands to
read signal strength. Better yet though would be commands to
setup all the right signal generator + spectrum analyzer
parameters and control frequency / etc over the course of the
measurements.<br>
3) Once the data is there in RAM, it needs to be made presentable
somehow on the web. WebGL is sounding like a good option for
rendering these 3D images in browsers. People should be able to
move the shape around and zoom in/out on it. There should also be
sliders to control any other dimensions, like frequency, or
polarity angle. Right now, I'm not aware of any widget that can
present such data on the web. It would also be good for the data
to stay in its raw form on the back-end so that it can be computed
on easily in future (unpredictable) ways. The first radiation
pattern I showed you is rendered in real-time by the web server
from a couple arrays pasted into the wiki page. A similar
approach in 3D land would be good.<br>
<br>
Does any of this sound interesting? Between Rob Salsgiver and
myself, we can provide all the necessary hardware. It's the
software we're missing. You can see my current 1D software on the
<a
href="https://www.hamwan.org/t/tiki-index.php?page=Antenna+Analysis&structure=HamWAN">Antenna
Analysis</a> page, attached at the bottom.<br>
<br>
Let me know if this or something else would be up your alley,<br>
<br>
--Bart<br>
<br>
<br>
On 4/27/2013 10:16 PM, Caleb Skurdal wrote:<br>
</div>
<blockquote
cite="mid:CA+Go_rTV5TaSNAMq3B3FdxqemE4HZz6EDciDJDe-RKEyMP1Fiw@mail.gmail.com"
type="cite">
<p dir="ltr">Hi all,<br>
I'm Caleb Skurdal AD7U. I met Bart today at the Northwest Linux
fest in Bellingham. I've been a ham for about 17 years; though
I've been tinkering with electronics for over 22. I have a
Computer Science background and all levels of the network stack
I find highly interesting. This an exciting project from the
purely technical standpoint and I see it as very valuable to the
community from a emergency preparedness perspective. I'm excited
to learn more about the project and hopefully to be able to
contribute to successfully implementing and growing it.</p>
<p dir="ltr">Regards,<br>
Caleb Skurdal</p>
<br>
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</blockquote>
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