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[aprssig] station capability flags

Tapio Sokura oh2kku at iki.fi
Thu Mar 1 19:00:21 UTC 2007


Jason Winningham wrote:
> There was some discussion in the past few days about not knowing  which 
> stations were acting as Igates.  One thing that has always  seemed 
> missing in the APRS protocol is a way to indicate station  attributes.  

What about the '<' packet type, defined on page 77 the APRS spec. Isn't 
that exactly what you are looking for? The spec wording says it is only 
to be used as a response to queries, but I've seen applications that 
send those packets periodically, without being queried for. There should 
be a list of station capabilities maintained separately from the spec, 
so that new "flags" can be easily defined, but I'm not sure if there is 
such a list.

> In the absence of a dedicated field added to the protocol, it seems  to 
> me we could get a very limited set of flags by using the TOCALL  SSID 
> bits.  A quick scan of my tnc log file didn't show any TOCALL  addresses 
> using an SSID other than 0.

That would be very limited indeed, just four independent bits. The mic-e 
flooding system already defines a use for the destination callsign SSID, 
but I haven't seen it implemented anywhere. I'd rather see a text/ascii 
flag of some sorts used in the body of a packet, maybe '<', '>' or in 
the comment part of a regular packet.

   Tapio




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