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[aprssig] KJ4GQV ClusterBalloon Flying

Joe Dubner jdubner at gmail.com
Fri Jul 30 13:24:29 UTC 2010


Matti Aarnio <oh2mqk at sral.fi> wrote:

> Above altitude of 3000 feet one should use at most WIDE1-1, preferrably
> no via paths at all.  Think about how many receivers a flyer does reach
> directly with their transmission.

Aside from WIDE1-1 being a poor choice of paths for an airborne station, 
lets talk about altitude.

What's so special about an arbitrary altitude?  Is that 3000 feet MSL 
(mean sea level) or AGL (above ground level)?  In the western USA (like 
Idaho), there's a big difference.  What should an airborne station do 
when flying in a remote area, a mountainous area, or an area of poor 
Igate or digipeater coverage?  Is the pilot of a small aircraft expected 
to actively manage his path "on the fly", adding to his workload while 
taking away from his priorities: aviate, navigate, communicate?  For the 
tiny percentage of the time that an airborne station is transmitting, 
can't the network afford to take some "abuse"?

My point is that a "one size fits all" solution with regard to altitude 
is not a solution.  In my own airborne experience, I've found that 
long-delayed packets are a serious problem even with the most benign 
path (WIDE2-1) that gives coverage at lower altitudes (where good 
coverage is desirable from a final position or a search and rescue 
standpoint).  After all, each flight ends at 0 AGL :-)

Reaching a large number of receivers is an unfortunate aspect of 
airborne operation.  IMO the APRS-IS and the APRS tracking web sites 
need to do better duplicate packet filtering.  For years I've been 
frustrated by aprsworld.net (RIP), findu.com and aprs.fi reporting 
duplicates so late that my aircraft was already on the ground when they 
arrived.  Once I received three packets from Nevada more than 24 hours 
after they were sent (and first received)!

I don't know what the total solution is.  But a partial one is within 
reach.  I created a tracking site for my own aviation needs that 
attempts to remove ALL bad, bogus, and duplicate packets 
(http://www.mail2600.com/cgi-bin/everyone.cgi) from my APRS-IS feed. 
Other aviators are welcome to use it too.  It doesn't track balloons or 
helicopters but it could if someone requested that.

73,
Joe, K7JD
Long-EZ 821RP



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