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[aprssig] Multiple SSID's from one station, with the New N Paradigm.

Keith VE7GDH ve7gdh at rac.ca
Sat Dec 13 22:08:53 UTC 2008


Dave G0WBX wrote...

> Following the recent IARU R1 meeting in Cavtat, and the resulting
> recommendation that Region 1 adopts the Newn-N paradigm...

I was pleased to hear that. There's a lot to be said for having
universal settings that will work everywhere without having to reprogram
as you travel.

> several people in the UK APRS network have been investigating how best
> to adopt it.  Notwithstanding that many think it's not necessary to
> change from RELAY,TRACEn-N to WIDE1-1,WIDEn-N etc, for many reasons,
> not least this following behaviour seen on air..

> 2008-12-08 14:36:12 UTC:
> G7III-15>APRS,MB7UW*,WIDE5-3,qAR,G0CGL-12
> :!5124.12N/00046.23W& Test Dup SSID: W5-5

> 2008-12-08 14:36:21 UTC:
> G7III-14>APRS,MB7UW*,WIDE5-3,qAR,G0WKM-2
>:!5124.12N/00046.23W& Test Dup SSID: W5-5

> 2008-12-08 14:36:25 UTC:
> G7III-13>APRS,MB7UW*,WIDE5-2,qAR,G0WKM-2
> :!5124.12N/00046.23W& Test Dup SSID: W5-5

> 2008-12-08 14:36:36 UTC:
> G7III-12>APRS,MB7UW*,WIDE5-1,qAR,G0WKM-2
> :!5124.12N/00046.23W& Test Dup SSID: W5-5

> Note the decrementing SSID of G7III, this is caused by a digi
> somewhere in the network, but is proving illusive to track down. G7III
> of course only used one SSID, -15.
>
> It is (again I'm told) one of the main reasons why the UK (well,
> England at least) has stuck with RELAY,TRACEn-N as it doesnt happen
> with that path method.

In North America, we have made WIDEn-N traceable and the old TRACEn-N
isn't used... except for a few hold-outs. We could instead adopt
TRACEn-N and make that traceable againa, but that would involve a change
for many thousands of users. Not that it makes a lot of difference, but
WIDEn-N saves one byte compared to TRACEn-N, but of course the length of
the digipeated packet increases each time it is digipeated. However, the
advantage is in being able to see the actual path and no dupes. Yes, you
have tht now with the old TRACEn-N, but I think it is a very worthwhile
goal to have universal settings.

RELAY isn't traceable and can lead to dupes and ping-ponging between
digis.

In the example above, it appears the SSID was changed by the
originating station... G7III-15, G7III-14, G7III-13, G7III-12. The
beacon comment indicates "Test Dup SSID". Are you saying that G7III only
transmitted with one SSID? If so, something screwy is going on.

> Someone has said this...   "...there is a D700 somewhere with UIFLOOD
> set with NOID enabled." Is this the case, or is there something else
> happening?

I'm not sure what is causing it.

> Was this odd behaviour seen in the USA when the New WIDEn-N system was
> first rolled out?   If so, how did you track it down and fix it?

No. There was a transition period where most digis and mobile stations
changed over, but I've never heard of what was shown in the examples you
provided going on if the originating station wasn't changing the SSID.
Perhaps someone within earshot of G7III and some of the nearby digis
might be able to observe what is going on. The WIDEn-N should decrement. 
The callsign-SSID of the originating station should most definitely be 
changing.

73 es cul - Keith VE7GDH
--
"I may be lost, but I know exactly where I am!"




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