[aprssig] Status text?
bruninga at usna.edu
Sun Jul 20 18:39:17 CDT 2008
> Should the status text be one of the canned
> Mic-E messages or is any suitable status
> message proper?
Good question. When the Mic-E format came out, things got a little overlapped. APRS was dsigned with two fixed packets per station, STATUS and POSITION (not counting messages)... These packets were separate and distinct, and each station could only have one STATUS and ONE POSITION at a time.
STATUS gave each station something like 57 bytes of free text.
POSITION allowed only something like 37 bytes of free text.
But then Mic-E came out and we wanted to combine everything into one packet. Plus we had 3 extra bits. So here is what
we have in a Mic-E packet:
2) 3 comment bits (1-of-7 predefined words)
3) Freefield on the end...
Now what to call the free field on the end? Since we already defined the 3 comment bits, then we decided to call the postion text in a Mic-E packet as STATUS.
So in conclusion. When we say STATUS packet we are taling aobut the independent long STATUS packet which is independent of position. But when we talk Mic-E the word STATUS refers to the free field text that is added onto the Mic-E position.
In APRSdos, on receipt of a Mic-E packet, all of the information about the packet is parsed into the POSITION packet as in:
And the text is parsed and saved over in the STATUS field.
Hope that helps.
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