[Xastir] A problem decoding PHG...

[Tom Russo]

On Wed, Nov 15, 2006 at 11:05:58PM -0500, we recorded a bogon-computron collision of the <kf4otn at ericsatcom.net> flavor, containing:
> Okay.  So there shouldn't be a PHG statement at the end of the weather
> data?  That is interesting.  I know that UIView doesn't integrate the
> PHG in like Xastir does so John (KE4TZN) was simply putting the PHG
> statement in the comment portion of the station ID so it would be in there.

Ah.  Well it's certainly wrong just to bung it into the comment field.  The 
PHG data belongs in a specific place in the information field; specifically 
PHG belongs in the "Data Extension" field, right after the symbol code in byte 
28 of the packet, according to the spec.  No spec-compliant software should be 
decoding it from the comment field.

> I wonder if there is a way to modify the spec to include these
> situations?  

Sigh.  The spec is pretty well ossified, although there are a large number
of "errata" out there on Bob B's web site.  You could always ask on APRSSIG, I
guess, but let us know when you before you do so --- I, for one, need to 
order a new asbestos suit before reading any subsequent traffic over there.

> If a digipeater were setup to also be a weather station
> you'd definitely want to know the approximate coverage area.

Yep.  Such a digi should be transmitting extra packets with a station 
comment (containing a canonical set of information to show its capabilities)
and PHG info.  It is not enough for it to just burp weather info.  This is
usually done by programming a set of beacon strings into its TNC to be 
sent out at infrequent intervals.

-- 
Tom Russo    KM5VY   SAR502   DM64ux          http://www.swcp.com/~russo/
Tijeras, NM  QRPL#1592 K2#398  SOC#236 AHTB#1 http://kevan.org/brain.cgi?DDTNM
"And, isn't sanity really just a one-trick pony anyway? I mean all you get is
 one trick, rational thinking, but when you're good and crazy, oooh, oooh,
 oooh, the sky is the limit!"  --- The Tick