[Xastir] IS to RF igating

[Tom Russo]

On Sat, Mar 22, 2014 at 10:21:56AM -0700, we recorded a bogon-computron collision of the <ksaves2 at sbcglobal.net> flavor, containing:
> ? With Jason's gps2aprs.pl script, method #2, one goes to the "Interface" drop down, selects the "Enable Sever Ports" button, waits a few seconds, then fires up the gps2aprs.pl script in another terminal.? This takes the raw NMEA data and injects it into Xastir as an APRS packet. Once the script is running, one sees the raw NMEA data coming in on the terminal which can then be minimizied.? The only problem with this method is Xastir doesn't recognize this "station" as something to digipeat.


There are two ways to do it --- add the call-sign of the data from gps2aprs.pl
to the nws-stations.txt file so Xastir DOES gate it, or have the script
create OBJECTS instead of station data.

The cleanest fix for this to make Xastir transmit this data is to make the 
gps2aprs.pl script create an *OBJECT* rather than a regular station posit.

  callsign>TOCALL:;<9 character object name>*POSITDATA

where TOCALL is an appropriate choice, probably one of the "experimental"
tocalls like APZ<your initials>, "callsign" is the call sign of the Xastir
program, and POSITDATA is one of the NON-NMEA style posits with timestamp.

Because of the way that Xastir processes object packets, it will see its own
call sign in the packet and think it created it, then beacon it on RF.  That's
because when Xastir creates an object, it just constructs the packet and
sends it through its incoming data processing routines, and relies on this
mechanism.  Faking it out by injecting a packet through the server port
with its own call sign gets the job done.  It doesn't process its own
station posits this way, though, so the technique only works with object
posits.

Since gps2aprs.pl is using the NMEA format packet (slapping an APRS header 
on a raw NMEA string from a GPS) this would be a little bit of work, because 
object packets don't work with raw NMEA sentences.  But parsing the NMEA 
sentences enough to extract the data needed for a regular posit isn't *that* 
hard.  Just need to pull out the date/time, lat/lon, course and speed (which
means combining data from a couple of different sentences, I think).  

-- 
Tom Russo    KM5VY   SAR502   DM64ux          http://www.swcp.com/~russo/
Tijeras, NM  QRPL#1592 K2#398  SOC#236        http://kevan.org/brain.cgi?DDTNM
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