[Xastir-dev] understanding APRS messages from xastir

[Kristoff]

Hi all,


I am working on a project to extend the firmware of the TTGO 
(aprs-over-LoRa) iGate software.
https://github.com/on1arf/LoRa_APRS_iGate


I am currently doing some additional work on the APRS-IS to RF gateway, 
specially for APRS "Message" packets.


I am using xastir on my linux laptop to test out my code.
(my igate has ON1ARF-12, my linux laptop/xastir has ON1ARF-14)


A test message I received is this:

ON1ARF-14>APX215,TCPIP*,qAC,NINTH::ON1ARF-12:test 1.2.3.{3y}12


Can somebody help interpret this message?

Looking at the "APRS 101" document (which I guess can be considered to 
be the more-or-less official specification for APRS), this seems to be a 
normal "Message" APRS-message, with message identifier (which should be 
acknowledged by a reverse "ack" message).

But as I had just previously received a "ack12" in a previous message 
from the xastir station, it looks like that the "{12" is in fact a 
repetition of that.


So, can I interpret this message as a combination of two messages: "test 
1.2.3.{3y" and "ack12"

I do not find anything in the "APRS101" document (version 1.0.1 d.d. 29 
Aug 2000) that describes this kind of "two-in-one" messages.

So, I am a bit confused why xastir sends this kind of messages packets.



Can somebody shed some light on this?


73
kristoff - ON1ARF