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[aprssig] UAH ballooning report (long)

Jason Winningham jdw at eng.uah.edu
Mon Apr 11 13:44:07 UTC 2005


On Apr 11, 2005, at 8:13 AM, Robbie - WA9INF wrote:

> Bad enough to transmit in the blind on the ground, now put something 
> up 10,000 feet transmitting in the blind???

Once the balloon gains a little altitude, it can hear several states.  
On one flight, packets were received in 11 states.  If you wait for a 
clear channel on 144.39 you will NEVER transmit under those conditions. 
  We accidentally flew one that was waiting for a clear channel to 
transmit; we got a bare handful of packets during the flight, other 
than those at the beginning and end while it was still close to the 
ground.

I don't recall if I mentioned this previously, but we ran our alternate 
trackers on 144.340, and I set up an Igate here at UAH on that 
frequency.  The antenna was low gain and low to the ground.  It managed 
to receive data anywhere from halfway through to flight to almost on 
the ground (it helped that all 3 of Saturday's balloons landed on top 
of the mountain).

The 144.34 stations were:

kg4wsv-15 - igate, Alinco DR-135TP, 1/4 wave ground plane
kg4wsv-10 - backup tracker, opentracker, yaesu vx150 on low power, 
vertical dipole
n4txi-11 - backup tracker/cutdown, WhereAVR, not sure about radio 
(Alinco DJ-S11?), horizontal dipole
wb8elk-11 - backup tracker, WhenAVR (variant of WhereAVR), I think 
Alinco DJ196 on low power, factory rubber duck

These are mildly interesting to look at, just to see the difference 
between a rubber duck and a dipole, or between vertical and horizontal 
dipoles.

It would be nice to have some 144.34 digis in the region when we fly, 
but for now we need to make use of the 144.390 infrastructure so that 
we can recover our payloads.  I don't think we have received any 
complaints, even though we transmit pretty aggressively for 2 or 3 
hours per flight.  I think most hams are still experimenters at heart 
and are interested to see something like this happening, rather than 
getting upset that someone is transmitting in the blind every 30 
seconds.

-Jason
kg4wsv





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