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[aprssig] Someone's Server Mangling Packets

Pete Loveall AE5PL Lists hamlists at ametx.com
Wed Jan 25 13:57:27 UTC 2012


Bob,

Your theory may be correct for a very few instances although the CRC in AX.25 is a significant deterrent to these originating on RF.  In this case, it is bad software.  The manglings shown are software concatenations and software modifications to headers and are numerous.  No RF bit errors involved with these.

My plea to software authors stands.  And if this was something identified and corrected, please strongly notify your software users to update to the latest release.

Thanks.

73,

Pete Loveall AE5PL
pete at ae5pl dot net



> -----Original Message-----
> From: Bob Bruninga
> Sent: Wednesday, January 25, 2012 7:45 AM
> 
> However, if we realize that almost every packet heard these days is a
> concatenation of one weaker packet overlayed with the most recent
> strongest packet, and since the ending flag is the same as a beginning flag,
> there is a finite probability that the sum of a few bit errors could result in a
> concatenated packet with a valid checksum at the end...
> 
> I think I theorized this once before, and maybe someone shot it down, but
> I'd like to see the probabiltites again...


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