[aprssig] AX.25 RR bit test - possible format

Pete Loveall AE5PL Lists hamlists at ametx.com
Wed Dec 5 06:52:06 EST 2012

The APRS-IS servers intentionally remove all non-TNC2/AEA format information from the headers as that information (such as timestamps, etc.) is misinterpreted by many clients.  Your suggestion of mangling the TNC2 format for the header will not work and may cause such packets to be discarded.  You do not have the option of mangling headers to convey AX.25 information with APRS-IS.

As stated by others, trying to use AX.25 -reserved- bits to convey higher level protocol information shows a lack of understanding of the overall consequences of such actions.  The frequencies world-wide that are used for APRS are -shared- among multiple uses, not just APRS and any alteration of the AX.25 communication protocol will have unintended consequences.


Pete Loveall AE5PL
pete at ae5pl dot net

> -----Original Message-----
> From: Robert Bruninga
> Sent: Tuesday, December 04, 2012 5:05 PM
> Come to think of it, however we will display these bits, we cannot mess up
> the present display of the FROM>TO calls and the display needs to separately
> display the bits for each of the header callsign fields.
> One method might be something like [RR:FFTTDDddDDdd...] inserted like
> TNC's do when they display the MCOM <UI> and other such parameters
> Where [RR:...] identifies the overall format of reporting the RR bits Where FF
> are the values of the FROM RR bits Where TT are the values of the TO RR bits
> Where DD and dd ... are the values of each digi field (up to seven pairs)
> Just a thought.  We cannot easily insert the [FF] and [TT] and [DD] in every
> field without having to redo a lot of parsers, so I though putting them all in
> one BRACKET field might be an idea...

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