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[aprssig] APRS in caves! (mammoth map) & HF

Greg Dolkas ko6th.greg at gmail.com
Tue Nov 20 04:06:12 UTC 2012


HF penetrates wet rock?  Cool.  Now if we can figure out a way to correlate
multiple HF signals, maybe build a poor-man's underground-capable GPS?
Sort of like what SSTV is to NTSC...

Ok, crazy thought.  But so far the only location information you're going
to get is either a manually entered coordinate, or a guess based on your
path to the exit node.

Greg  KO6TH


On Mon, Nov 19, 2012 at 6:03 PM, Robert Bruninga <bruninga at usna.edu> wrote:

> HF VERTICAL LINKS:  I just realized that since HF penetrates a few
> hundred feet vertically, we can use HF to link up to the surface every
> 7 hops or so.  Just an FT-817 with a DIPOLE above and below ground
> hooked to a TNC can provide the link  Once above ground, then hops
> continue on VHF.
>
> Each vertical link takes up 2 hops, but it sure beats having to do 14.
>  We need some people experimenting with HF packet FM (with squelch) on
> 80m (below ground since it would not be legal above ground)...  I
> gotta do some research on HF links...
>
> Also this gets more hams involved.  SOme hams not prone to caving, can
> man the top side stations.  One of the HF links will be right in the
> Lobby of the hotel and since it has WIFI, then that can be our IGATE!
>
> > With this map, there's no easy way to separate the above-ground
> > elevation contours from the cave tunnels.
>
> Not sure I follow.  The tunnels are dark black.  Everything else is
> color.  Its too early to start a huge investmnt in manually crossing
> over the data to a vector file until I find out "which" path is the
> MAIN CAVE.  The big portions are easy, but there are many places where
> there are multiple thin lines.
>
> > Also, is this just the first level of the cave, or is it
> > several vertical levels drawn together?
>
> all 6 levels.  So crossing black lines do not necessarily mean a
> connection.
>
> Bob, WB4APR
>
> > Andrew Pavlin, KA2DDO
> > ------Original Message------
> > From: Robert Bruninga
> > To: APRS at yahoogroups.com
> > Cc: aprssig at tapr.org
> > Sent: Nov 19, 2012 4:58 PM
> > Subject: Re: [aprssig] [APRS] APRS in caves! (mammoth map)
> >
> >
> > Mammoth cave underlay on local terrain map is now complete.  The map has
> a
> > LAT/LONG grid on the sides so one can pinpoint one's position into the HT
> > underground to the same 0.01 Minute of LAT/LONG as on the surface.
> >
> > See http://aprs.org/cave-link.html
> >
> > So far, none of the modern clients seem to do GIF or JPG files.  But as
> we
> > get closer to the 2 March 2013 test, maybe someone can develop a vector
> > overlay for the main passage.  Can YACC or APRSIS32 do APRS Overlays?
> >
> >
> > Bob, WB4APR
> >
> > _______________________________________________
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> >
> >
> > Sent from my Verizon Wireless BlackBerry
> >
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