> Hi all,
>  I have a question for those analog engineers on the list.  I have been s=
earching
> the internet for information on listening to ELF signals.  I have found s=
ome
> information but not exaxtly what I'm looking for.  For example one site h=
as a
> circuit of amplifiers and passive filters utilizing either an antenna or =
just probes
> stuck in the ground to receive ELF signals below 50Hz.  Another person ha=
s a very
> large coil of wire wound on a spool and just sets it on the ground.  What=
 I would
> like to do is similar but I'd like to listen to 76Hz which is the US subm=
arine
> communications frequency.  The Russians utilize 82Hz.  Is it possible to =
build a
> circuit that would pickup the 76Hz signal only?  Any information on how t=
o do this
> if it is possible is appreciated.
> Thanks,
> FJ
>=20
> http://www.vlf.it/kurt/elf.html

Do they still use ELF? I had been given to understand that they use lasers =
from spacecraft these days, green blue lasers penetrate the water quite wel=
l apparently, and the resultant data rate is much faster than ELF, and has =
a potentially bidirectional path.
--=20
Scanned by iCritical.

--=20
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