[aprssig] Impossible to be digi+something else?

Lynn W. Deffenbaugh (Mr) ldeffenb at homeside.to
Wed May 11 09:22:37 CDT 2016


I have asked this question several times and the answer is always the 
same.  Digipeaters are not supposed to delay their digipeated packet, 
but ARE supposed to wait for a clear channel.  So they're "semi-polite" 
as it were. From http://www.choisser.com/packet/part03.html (a 
definition of DWAIT):

> *DWAIT*: Used to avoid collisions, *DWAIT* is the number of time units 
> the TNC will wait after last hearing data on the channel before it 
> transmits.

So a DWAIT of zero will not stomp on other packets, but will jump in as 
soon as they "last heard data on the channel".  Not really monopolizing 
in my book, just being aggressive with getting their data on the air.  
As long as the digi's other packets are not too long, too frequent, or 
too numerous, I wouldn't see a need to modify the DWAIT by packet type.

Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32

On 5/11/2016 9:44 AM, spam8mybrain via aprssig wrote:
> I was re-reading some of the old postings about digipeating, where 
> they state that digipeaters (only) should be "impolite" and use a 
> DWAIT of zero to avoid channel clutter. This would seem to imply that 
> no station can be a digipeater and something else (weather station, 
> etc.) unless the full functionality is built into the TNC, because 
> there is no way for an external application to tell a KISS TNC on a 
> packet-by-packet basis which packets are DWAIT 0 and which are to have 
> normal competition for airtime. Either the digi would be "polite" and 
> cause additional airwaves clutter, or the non-digi functionality would 
> be "impolite" and dominate the channel.
>
> So, do any of the "soft" TNCs (AGWPE, DireWolf, etc.) have the ability 
> to specify priority (DWAIT=0) transmission on a per-packet basis? How 
> does this jive with the proposed sat-gate mode?
>
> I'm curious because I'm doing some research on an idea for improved 
> digipeating, and it requires using an external program with a KISS 
> TNC. As such, I'd like to be able to selectively decide whether my 
> station is "polite" or "impolite" on a per-packet basis (assuming 
> impoliteness is still preferred digipeater behavior).
>
> Any feedback would be welcome.
>
> Andrew Pavlin, KA2DDO
>
>
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