[aprssig] Digpeater setup

Bill Vodall wa7nwp at jnos.org
Thu Mar 31 12:37:55 CST 2005

> Please explain how RELAY causes DUPES? If I am understanding it, a dupe 
> is when a station retransmits a packet that was digipeated by a previous 

An unnecessary duplicate (the vile root of all evil DUPE) is when one digipeater
sends the same packet more then once.

The problem is the Kantronics boxes don't check on the RELAY alias like they
do on the UIFLOOD(was WideN-n) and UITRACE(was TraceN-n, now WideN-n)

Assume two local Kantronics digis - k7gps and ka7pbi.

WA7NWP-9 transmits:

  WA7NWP-9>APFOO,RELAY,WIDE2-2:>Ban Dumb Trackers

Both hear me and retransmit:

  WA7NWP-9>APFOO,K7GPS*,WIDE2-2:>Ban Dumb Trackers
  WA7NWP-9>APFOO,KA7PBI*,WIDE2-2:>Ban Dumb Trackers

and then both hear the other and retransmit.

  WA7NWP-9>APFOO,K7GPS,KA7PBI*,WIDE2-1:>Ban Dumb Trackers
  WA7NWP-9>APFOO,KA7PBI,K7GPS*,WIDE2-1:>Ban Dumb Trackers

Those are both DUPE's.   A network clogging waste of air time.

Add a couple home RELAY's, and it would get even worse.

Now --  If both KA7BPI and K7GPS digis used UI-DIGI or DIGI_NED with
pre-emptive digipeating -- there would be no dupes and the resulting packets would

  WA7NWP-9>APFOO,KA7PBI*,WIDE2-1:>Ban Dumb Trackers
  WA7NWP-9>APFOO,K7GPS*,WIDE2-1:>Ban Dumb Trackers

So - the simple solution is to use better technology.   Relegate the dupe generating TNC's to
Airmail or for Smart Trackers.  Use old 1270's with UI-DIGI or KISS Eproms/DIGI_NED for
infrastructure digipeaters and nodes..

Hey Curt - how about another option to your network analyzing widget.   You could count
the digis of the various types.   What get's measured -- get's better.

Bill - WA7NWP

PS.  KA7PBI already uses DIGI_NED and I'm sure he'd rather drink (B) then switch.   K7GPS
needs everybody on the SIG to send him an APRS message with the contents:  #53...  (That's
our inside joke...)

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