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

AE5PL Lists HamLists at ametx.com
Tue Aug 9 17:28:54 EDT 2005

Again, this was not an issue with APRS-IS but a specific station,
possibly the IGate.  We have seen delays where packets are stored at
end-points but this is still a RF or RF interface problem, not an
APRS-IS problem.  We have also seen clients retransmit a position report
when the GPS goes out of sync.

Also, the reason there is only a 30 second duplicate check is to prevent
the breaking of APRS messaging, more than any other reason.  Longer dupe
times would prevent messaging retries from properly traversing APRS-IS.
The reason there is no packet identifier is because it is not in the
protocol and over a thousand clients and servers would have to change if
the APRS-IS inter-device protocol were substantially changed.

So, again, look at RF first, even if it seems that the IGate heard the
packet directly.  If you think that the IGate may be the problem,
contact the IGate sysop directly, not here.  But don't assume that it is
the IGate because you will usually be wrong.


Pete Loveall AE5PL
mailto:pete at ae5pl.net 

> -----Original Message-----
> From: J T
> Posted At: Tuesday, August 09, 2005 1:13 PM
> Subject: RE: [aprssig] "Out-of-order" data on APRS-IS
> Pete,
> Keep in mind Mark said this problem also happens when no 
> digipeaters are involved -- i.e. cases where multiple I-gates 
> hear the same packet directly.

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