[Xastir] IS to RF igating

[Tom Russo]

[Reposted to the Xastir mailing list for archiving of response]

The topic is using a script to generate posits, using a similar script to
generate APRS Objects instead, or using the incoming NMEA stream as a 
"system GPS" for the Xastir instance itself.

I had recommended changing the script to do objects instead, but that's
a bit harder than it sounded because the script itself is very simple.

On Sat, Mar 22, 2014 at 11:13:58AM -0700, we recorded a bogon-computron collision of the <ksaves2 at sbcglobal.net> flavor, containing:
> 
> [...] here's the script that Jason wrote [...] [script sent in private email]

Yeah, since that script just takes the raw NMEA strings and tacks on an APRS
header, it's extraordinarily simple.  

To do what I suggested means you have to parse them, save the data, and 
reconstruct a new posit.  If I were implementing it, I'd have a loop that 
reads the NMEA strings and parsed 'em (where now all it does is prepend some 
text and send it off to Xastir), saving the position, velocity and 
course each time into "my current data" variables, then tested the time since 
last posit creation --- if the desired interval passed, construct the new 
object data and pass it to the server port.  Could be a fun exercise, but
definitely not as simple as what you have.

Maybe your system GPS idea is the best one to use.  There are ways around
the 6 second limitation you mention...

> With the NMEA receiver attached as the "system GPS" the frequency is limited 
> to once every 6 seconds.

The reason Xastir is limited to 6 seconds minimum is because of how it 
calculates the interval from the timing slider, which limits it to .1 minute
increments.

But this number from the slider is converted back to a rate in seconds to
be stored in the xastir.cnf file.  On restart, the config file is read to get
the rate in seconds again, and the dialog slider issue is not triggered
again unless you open the configure timing dialog and save the settings.  So 
if you open xastir, set the posit rate to .1 minute using the slider, then 
exit, you'll find that it's stored POSIT_RATE:6 in the config file.  If you 
manually edit that to POSIT_RATE:4, restart xastir and then never even open 
the configure dialog slider again, it will just use the value from the config 
file from then on.

Just remember to set it to something sane again before you use xastir on 
144.39!
 
-- 
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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