[HamWAN PSDR] Hello

[Bart Kus]

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:

./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:

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
>
>
>
> _______________________________________________
> PSDR mailing list
> PSDR at hamwan.org
> http://mail.hamwan.org/mailman/listinfo/psdr_hamwan.org

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