[aprssig] Final Web Page for AE0SS-11 and KC0YA-11 Balloon Launch Up -- APRS-IS Problems

Stephen H. Smith wa8lmf2 at aol.com
Sat Mar 12 14:41:57 EST 2011

The dual launch announced earlier is over.   The final summary page is now on 
my website at:


Major APRS-IS issues were evident

The actual downlink for APRS data from the balloons to the ground was on a 
private channel, that was then retransmitted on the usual 144.39 frequency to 
find it's way to igates and the APRS-IS (APRS Internet System).

Tracking of these launches were marred by severely-delayed packets being 
injected into the APRS-IS.  This causes more recently reported data to be 
superseded by older data. The result is tracks that "hyper-jump" 
forward-backward-forward-backward.    In the case of  aerial vehicles like 
balloon, they also bounce up and down in  altitude.  (Note the "grass" of 
vertical jumps on the AE0SS-11 vertical profile graph, and the hiccups on both 

Delays in passing packets from the TNC to the attached computer is a known bug 
in KPC3+ TNCs operated in KISS mode connected to a computer.  The problem 
appears randomly after several days or weeks of operation, and can be cleared 
by issuing the RESET command to the TNC or by cycling it's power  OFF and then 
back ON.  This problem primarily affects home digi/igate  stations, since they 
typically use a computer-based setup.   It does not affect KPC3+ TNCs operating 
in stand-alone mode, as would be the case with most remotely located digipeaters.

Further,  these  launches were  marred by one or  more TNCs at digipeater or 
igate sites operating in PASSALL mode (a.k.a. "junque" mode). Numerous posits 
with impossible values were passed including elevations hundreds of feet  below 
sea level,   wild hyper-jumps 100s of miles at right-angles to the track path, 
and multiple corrupted versions of the two balloons' callsigns.

The tracks were further confused by the balloon trackers apparently being 
powered up (for a test??) on the south side of the Denver metro area, before 
being taken to the launch site. Or were these posits sent before the GPS 
receivers achieved lock at the launch site?



Stephen H. Smith    wa8lmf (at) aol.com
EchoLink Node:      WA8LMF  or 14400    [Think bottom of the 2M band]
Skype:        WA8LMF
Home Page:          http://wa8lmf.net

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