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[aprssig] "Out-of-order" data on APRS-IS

VE7GDH ve7gdh at rac.ca
Wed Aug 10 02:00:19 UTC 2005


I've got my own "out-of-order" story. VE7CUU-14 came for a visit today. 
While viewing his track (UI-View32 / PMapServer 7 / UI-HeightTrack but 
that's irrelevant) I noticed that just before he got here, he jumped back to 
a previous position, and then on to what should have been the next position 
after the one that he "jumped back" from. I have seen this numerous times 
over in the Vancouver BC area, but this time, I was able to understand the 
evidence. Here are the last few position reports.

20050809171522,VE7CUU-14>TXUPQT,VE7SFU-10*,WIDE2-2,qAo,VE7DID-1:`39k/164.520 
SX
20050809171628,VE7CUU-14>TXTYVY,WIDE-2,qAo,VE7GDH:`38\o!gk/
20050809171632,VE7CUU-14>TXUPQT,VE7IPB-10,VE7CX-10,WIDE2*,qAR,KD7NM:`39k/164.520 
SX
20050809171723,VE7CUU-14>TXTYSU,RELAY,WIDE2-2,qAo,VE7GDH:`38Un!Qk/
20050809171801,VE7CUU-14>TXTYQU,WIDE-2,qAo,VE7GDH:`38An5$k/164.520 SX
20050809172019,VE7CUU-14>TXTXXU,RELAY,WIDE2-2,qAo,VE7GDH:`37Hlp!k/
20050809172125,VE7CUU-14>TXTYPW,WIDE-2,qAo,VE7GDH:`37]lq
k/
20050809172211,VE7CUU-14>TXTYPP,RELAY,WIDE2-2,qAo,VE7GDH:`37Fm+Tk/

It is in MIC-E format, but notice the first position shown `39k and gated by 
VE7DID-1. Then jump down two lines and you will see the same position again, 
but gated a full minute and 10 seconds later, but via a different path and 
gated by KD7NM down towards Seattle WA.

Someone had suggested earlier that it could be a digi not running with the 
squelch wide open and with it hanging onto the packet until the squelch 
eventually closed. I suppose it could also be a case of the frequency being 
so busy that a particular digi was holding off until there was a moment of 
silence before digipeating the "held" packet. There is also a possibility of 
some kind of a delay being introduced by KD7NM but you would think that 
others would have noticed it before now. Just thought I would throw this out 
at the SIG. I will send a copy to the NWAPRS list shortly to let the 
"locals" mull it over.

By the way, ignore the typo in the status text. It should of course be 
146.520 SX. That will be re-programmed shortly, as well as getting rid of 
the RELAY in the path. Also I was just gating the beacons I heard. I don't 
digipeat anything via RELAY.

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






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