[Xastir] FIltering FOR NWS Watchbox Polygons

[Eric Germann]

Colleagues,

I spent some time last night beating my head on the wall trying to figure
out why NWS Watch/Warning polygons weren't coming up when I zoomed way out
to watch the storms a couple of states away.

So I brought up their polygons via SHP files and couldn't see them.  Of
course, without a dbfawk file, they're black, so on my black background,
they were missing.  Problem solved there.

But I still couldn't figure out why the "normal" watch warning polygons
weren't coming up.  Today they're up since we're getting hammered again in
West Central Ohio.

Then it dawned on me.  They're coming via APRS-IS feeds and I have a 320km
radius filter set.

What I want to accomplish is to have nationwide watch warnings without
polling NWS every couple of minutes.  Seems like the way to do it is to
create another link to my internal APRS server (which is linked to
APRS-IS, so I don't have a bunch of clients polling the core) with a
filter set to only catch the polygon announcements.  Only issue is, I
don't what the packets look like or how to build that filter.  I'd like to
keep the 320 km limit for stations which is a pretty good field of view on
a 22" monitor.

Any ideas, thoughts?  Or would the better approach be to just use the NWS
files for farther out and write up the dbfawk files (not an issue to do
that).  As an academic exercise, the multiline polygons would be
interesting over APRS and filtering them.

73 de N1ICS
Eric