[Xastir] Davis Weather APRS Data Streamer

[Tom Russo]

On Fri, May 15, 2009 at 10:41:31AM -0600, we recorded a bogon-computron collision of the <k5mts.xastir at gmail.com> flavor, containing:
> Hello all,
> 
> I'm new to Xastir and love the software, and I have a question.
> 
> With the new APRS Data logger for the Davis weather stations it is no longer
> necessary to poll the station for data.  Additionally the unit can stream
> data in APRS packet format as fast as every minute.  The data is formatted
> as such:
> 
> @151632z3500.03N/10620.88W_267/002g007t070r000p016P000h17b10219.DsVP
> 
> Is there any chance of implementing this in Xastir?  It would certainly take
> the headache out of trying to interface my station with MySql and the like.
> Thanks in advance,

Hmmmm.  I've been looking at this, and think that it would actually be 
even easier than I thought.

In wx.c there's a function "wx_decode" and another called wx_fill_data that
attempt to decode data from interfaces of type "Serial WX".  The code is 
convoluted and ugly as sin because it's a big "if/else" block, but the code
to recognize these Davis packets could be hacked in to those two functions,
and very easily at that.  The format is only *slightly* different from how
the "DAVISMETEO" block decodes things --- the only difference is the presence
of the (unneeded) APRS posit information at the beginning and the fact that
course and speed are indicated in "CSE/SPD" format instead of "cCSEsSPD" format.

Mike:  I can hack the code, but since I don't have such a unit I can't test it.
But what I can do is try to hack it into my copy, make sure the hack compiles, 
and then shoot you a "patch" file and instructions for applying it.  Then you 
can test it out and let me know if it works.  If it does, I'll commit it, and 
we can iterate if it *doesn't*.

-- 
Tom Russo    KM5VY   SAR502   DM64ux          http://www.swcp.com/~russo/
Tijeras, NM  QRPL#1592 K2#398  SOC#236        http://kevan.org/brain.cgi?DDTNM
  In some cultures what I do would be considered normal. 
                                  -- Ineffective daily affirmation