[aprssig] APRS in caves! HF & Experiment Ideas

Steve Noskowicz noskosteve at yahoo.com
Mon Nov 19 23:15:01 EST 2012

Hmmm.  Just some thoughts for possible experiments:

1 - What freq travels the best (longest) *in* the cave.  Reflections could be a problem for digital data...

2 - What freq is best for the "HF up-links".  This is a combination of freq and practical antennas.

3 - While a longer term experiment, there is magnetic communications, but probably higher than this 1.16kHz technique:

RE: legal vs. illegal frequency/mode combinations:
  ??  For short term experiments I don't think an STA would be necessary?  We're supposed to be experimenters, no?

73, Steve, K9DCI  

--- On Mon, 11/19/12, Robert Bruninga <bruninga at usna.edu> wrote:

> 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

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