[CRAPRS] aprs backbone for emergency communications

[djhuff at rockwellcollins.com]

My answer: sort of.
One of the limitations of APRS is that it relies on AX.25 UI, meaning that 
you can only send small packets of data.  (about 65 to 110 characters, 
depending on message formatting type)  So you may not be able to send a 
huge file, but you can use small messages.  UI-view has an addon that 
allows you to do something that looks like a chat client, 
<http://www.apritch.myby.co.uk/addon_agw.htm> you might be able to send a 
big file, but you have to do it small chunks at a time. 
There is also an app that lets you pass data at the AX.25 layer, 
UI-Messenger <http://www.kr1st.com/uimsg.htm> but I am not familiar with 
it. 

That doesn't even touch on the practical aspects of APRS, like the facts 
leared during disasters. (we can save that for another time)

Having said all that, the current QST had an article about NBEMS (Narrow 
Band Emergency Messaging Service) and K0ECW expressed interest about 
setting up a trial among Cedar Rapids users.  So far not much else has 
been heard.

David J Huff
Rockwell Collins Inc.




Jerry Pasker <info at n-connect.net> 
Sent by: craprs-bounces+djhuff=rockwellcollins.com at rf.org
08/05/2009 05:03 PM

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Subject
[CRAPRS] aprs backbone for emergency communications






Posting from the CRAPRS mailing list:
is it possible to use the large number of aprs high level digipeaters 
as ax.25 digipeaters?  1200 baud is slow, and my past experiences 
using it to transfer files (back in the early 90s, for storm chasing) 
used to yield a throughput of 600-900 bps when transferring files. 
and then even worse at 150-300bps when using a digipeater in the 
middle.  I know channel congestion would be a huge problem trying to 
use aprs digis, and it would be slow as heck, but in an emergency, 
you take what you can get.

you wouldn't surf the internet with it, and would not even attempt to 
transfer even graphical weather map files, but i envision a scenario 
where it would be desirable to be able to send simple text traffic 
that would be too hard to relay over the air with voice comms 
reliably.  for example, (from a year ago) a list of houses and names 
of those holding out and staying behind after a a flood evacuation....

aprs is entirely unnumbered and unconnected, and that's what makes it 
work well.  it also seems like that would lend itself to useful, but 
slow data communications over a fairly wide area.

anyone have any info on using digis to connect up to tncs far and 
wide, or passing files on 144.390?

-jerry
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