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[aprssig] bad Mic-e packets

Tapio Sokura oh2kku at iki.fi
Sat Apr 22 06:59:11 UTC 2006


Doug Ferrell wrote:
> 	I'm seeing bad mic-e packets (er...reported to me as being bad) at my Igate
> station with the "]" bracket. At first I thought it was aprsd but I went
> into terminal mode and I see the same thing. So I guess this is a TNC setup
> problem?  Below is a snippet that I edited to eliminate the callsigns so it
> starts after the colon.

I can't say for sure for those packets you showed, but a fact of life is 
that aprsd (the sourceforge.net version) breaks certain mic-e and some 
other APRS packets. It does that by replacing bytes that are under 32 
and over 126 ASCII value with a space. To be exact, it uses the 
isprint() function for determining whether to pass a byte or to replace 
it with a space. This bug has been there for ages and still is in the 
"current" (May 2003) release version.

Sometimes I see mic-e packets that have been truncated, possibly by some 
other piece of software that removes bytes with ASCII value under 32 
from packets. I guess it is also possible that the TNC you are using has 
a setting for passing only printable characters.

   Tapio




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