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[aprssig] NE Illinois Balloon Tracks

Jason KG4WSV kg4wsv at gmail.com
Fri Jul 24 14:51:24 UTC 2009


Lots of opinions, and many apparently from folks who haven't been
involved in ballooning.  I've been involved in 30+ flights, so I'll
throw my opinion out.

Yes, the 30s TX rate is too aggressive for 144.39.  That should be
done on an alternate frequency.

First rule of ballooning: Murphy is in charge.

You very well may NOT be in simplex range when the balloon goes down.
If the jet stream is involved, you may still be 50 or 75 miles uprange
when it lands.

Your payload may be damaged on impact.  Antennas seem to be especially
vulnerable.  Even if you figure out the approximate LZ, the tracker
may be dead due to impact damage by the time you get there.

There may be a mountain between you and the balloon as it goes down.

Your batteries may freeze, and the tracker may not come back to life
until it has been on the ground long enough to thaw out.

Your tracker may be in the default "good citizen" "listen for a clear
channel before you transmit" mode, and you don't hear it after 1000'
AGL until it hits the ground again.

For these and many other reasons, a multi-hop path is VITAL for
payload recovery.  Our teams have experienced all of these situations.

Not all trackers are capable of profile switching, to change a
multi-hop path for a direct path and back.

If digis are correctly configured, multi-hop related QRM should be
minimized since they will all retransmit at the same time, to avoid
ping-ponging.

Folks get excited because the balloon's RF footprint is a few hundred
miles, but remember that APRS is a _local_ network.  There is not a
lot of difference to the _local_ network in a balloon that can be
heard by the local digi beaconing once a minute and my truck beaconing
once a minute if I forget to turn it off when I go in to work (except
the traffic from my parked truck is pretty boring).

People are becoming hams because of ballooning.  Help and advice is
fine, but please don't be jerks about it.

-Jason
kg4wsv



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