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[aprssig] Point-to-point telemetry addressing

Robert Bruninga bruninga at usna.edu
Sat Nov 25 03:07:12 UTC 2006


> There is a good APRS digipeter (K2AMB-3) near W9IP-1 and
another good 
> one (KB2FAF-10) near W9IP-2.  

Several comments come to mind and I appologize if I appear to be
frustrated by the lack of fundamental information in the nearby
digis.  But this example shows exactly why the initiatives of
the New-N Paradigm are so important to network determination:

It is clear why WIDE2-2 wont work:

Looking at KB2FAF-10 on FINDU.COM,
 http://www.findu.com/cgi-bin/find.cgi?kb2faf-10

there is nothing to indicate it is a digipeater or supports any
of the modern APRS digipeating functions.  It is an Igate.  It
has no mention of support for WIDEn-N digipeating and most
importanly, it shows no indication of its PHG data which is
fundamental to a digipeater so people can infer its relative
coverage.  Without a digi symbol and without PHG data, it could
be an HT in someone's basement serving only as an IGate.

You say it is "near W9IP-2" but you also say the "terrain is
rough". Since the KB2FAF-10 station has no  PHG data, the word
"near" is practically meaningless.  It could be 1 mile away by
LAT/LONG, but could be in a basement on an HT and have a worse
path by far than a good digi 20 miles away that is on a good
high site.  This is why PHG (Power-Height-Gain data) is
fundamental to APRS and why all fixed APRS stations (home and
digis) should include this data in their beacons.

Looking at K2AMB-3:
http://www.findu.com/cgi-bin/find.cgi?k2amb-3
This digi has a good PHG, but it also has none of the modern
APRS indication of the proper settings for an APRS digipeater:
* it is using an obsolete WIDE,WIDE,WIDE path
* It does not indicate the type of TNC in its header, 
* it does not indicate its support of WIDEn-N, or limits on N
* it does not indicate its support of Nyn-N
* It does inidcate it is a TRACE digi which is obsolete

So it appears to me this digi does not support WIDEn-N in the
first place.  The owner of this digi needs to update its
settings in accordance with the 2004 recommendations for the
New-N Paradigm.  Since it is an old PACCOMM digi, it can be made
to work using those parameters found on this page:

http://www.ew.usna.edu/~bruninga/aprs/PacComm-settings.txt

And see this page for all the reasons that old digis like the
two in your area need to be set to proper settings..

http://www.ew.usna.edu/~bruninga/aprs/fix14439.html

Hope this helps.
Bob, WB4APR





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