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[aprssig] NE Illinois Balloon Tracks

Keith VE7GDH ve7gdh at rac.ca
Fri Jul 24 16:40:01 UTC 2009


Jason KG4WSV wrote...

> 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.

I've never been involved with a balloon flight but will throw my opinion
out. With 30+ flights, you must have learned a lot, both about the
balloon itself and the various payloads that you have flown - amateur or
otherwise. Hopefully you are sharing what you have learned about
the "do's and don'ts" of APRS with your fellow balloon enthusiasts.

> Yes, the 30s TX rate is too aggressive for 144.39.

Agreed... whether it's on a balloon or not.

> That should be done on an alternate frequency.

They could beacon as often as the wanted to on an alternate frequency,
but of course, on 144.390 they could take advantageous of the
terrestrial network and the APRS-IS.

> First rule of ballooning: Murphy is in charge.

Often, before the launch... i.e. programming the tracker.

> 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.

That is the nature of balloons turned loose into the atmosphere.

> 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.

That's always a possibility. I'm sure anyone involved with balloon
launches would try and "do it better" with every subsequent launch...
better packaging, more failsafe parachute, better batteries, more
survivable antennas and so on. I would hope they would be at least as
concerned about unsuspecting people on the ground as they are about
trying to make the package survive with a soft landing.

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

Always a possibility.

> 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.

That's unfortunate. Better luck next time.

> 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.

That would be poor planning. Anything that flies shouldn't be waiting
for silence before transmitting.

> 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.

Then they shouldn't be flying that tracker. It comes down to poor
planning and a poor choice of equipment. If they simply aren't aware
that there is off-the-shelf (and cheap) equipment that will both make
them better citizens and enhance their chance of recovery, they should
design and build their own intelligent controllers.

> 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.

Yes, digis should be configured properly. Balloons can EASILY change
their beacon rate and path based on altitude. I have at least a dozen
devices here capable of that and I'm not even involved with balloon
flights.

> 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).

If the horizon was 100 miles away, the footprint would be about 31460
square miles. I think that high altitude balloons with amateur payloads
are really exciting. There's probably no need for a balloon to beacon
often unless it's descending, or some other needed telemetry is included
in the beacon. At altitude, it doesn't need any digi path, but some
would argue for a one hop WIDE2-1. There's no need for your truck to
beacon every 60 seconds when you are moving, let alone while you are
parked. SmartBeaconing is a good solution for mobile stations.

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

I'm glad to hear that people are becoming hams because of ballooning.
Whether they are new hams or just new to APRS, they should take an
interest in APRS if it's going to be part of their payload. That means
learning enough that the are "good citizens" on the air. Even hams that
are not new to APRS can always learn something new about it. All too
often, the first we hear of a mis-configured tracker on a balloon is
after the balloon launch. If the people involved asked for advice well
before the launch, they would have time to gather the right equipment to
"do it right". Bob and some others argue that the impact of a balloon
with a tracker is no more than a "1 minute mobile driving though"  the
area. However, a properly configured balloon could have LESS impact than
a "1 minute mobile".

Of course, then there's that plane with the 3 hop WIDE1-1,WIDE2-2 down
south of me this morning. If it was a balloon at the same distance up at
100,000' with no path, I would be excited about it. On a plane at a few
thousand feet with a 3 hop path and a high beacon rate, it's just
another badly configured tracker 400-500 km from me that I didn't need
to see on RF. However, its impact was probably no worse than the tracker
with the 30 second beacon rate sending full NMEA sentences 40 km from my
location... also with a 3 hop path.

73 es cul - Keith VE7GDH
--
"I may be lost, but I know exactly where I am!"




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