[HamWAN PSDR] Hello

[Caleb Skurdal]

Hi Bart,
The first two items on the list are pieces I could do. The third I'd have
to look into more. I've never done graphics rendering so that may be better
left for others. Though it should be easy to find info on getting it
rendered.

What type of interfaces do the antenna rotator and microwave instruments
use? If you have model numbers or interface specs I can look up
documentation and see if I can design a software solution to setup,
interface, and control them all to work together.

I imagine getting a client server solution running with less than
milliseconds RT should take a few days. A direct web solution should be
simple.

I have raspberry pi Linux box that may work well.

Regards,
Caleb Skurdal
 Hi Caleb!

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.

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:

[image: ./temp/cache/6daf471697293d9e55e0b9a31e79da09_1.png]

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.

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:

[image: http://www.antenna-theory.com/antennas/reflectors/dish3.jpg]

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.

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:

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.
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.
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.

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 Antenna
Analysis<https://www.hamwan.org/t/tiki-index.php?page=Antenna+Analysis&structure=HamWAN>page,
attached at the bottom.

Let me know if this or something else would be up your alley,

--Bart


On 4/27/2013 10:16 PM, Caleb Skurdal wrote:

Hi all,
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.

Regards,
Caleb Skurdal


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