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From: Paul Nicholson <vlf0403@abelian.org>
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Date: Wed, 3 Jan 2018 18:01:56 +0000
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Jay wrote:

 > the BIG coil has since been decommissioned.

What a shame, it would at least have made a great Tesla coil.
But it illustrates the obstacle to getting going on VLF -
so few stations.  The nearest rx or tx is likely to be out of
range to begin with.

I couldn't have received W1VLF at the time, but 3 years
later there would have been a good chance.

Stefan wrote:

 > We were looking in 4.5 mHz spectrograms or wider...

Yes I was using MSF 60kHz for frequency lock and no absolute
phase reference.

Many incremental improvements since then, but the major gains
for receiving are use of GPS for timing (enabling much narrower
bandwidths and absolute phase reference), and use of strong
sferic blanking (which can gain up to 20dB).

For transmitting, also the use of GPS, and a move away from
inefficient modes such as QRSS, to MFSK and coherent BPSK.

I guess Paul W1VLF was just a couple of years ahead of us
there.

 > http://abelian.org/vlf/tmp/ss100315a.png

Gosh, 3 fT was a huge signal!   Now it is possible to decode
messages from 0.03 fT.

We should think about ways to encourage more interest in VLF.
I suspect that not many amateurs are aware of the activity.
Chatting with a colleague at work the other day, a radio ham,
he had no idea that people were operating at VLF.

There are about a dozen major amateur radio journals, but as
far as I know, none have carried any articles about VLF.

I would have thought that the big LF players at least, would
be interested.  Certainly those that have had a go have found
great success and in most cases they already have suitable
antennas and they know how to wind loading coils and build
hefty amplifiers.

Now I'm half tempted to write an article, but I can only write
about receiving.

--
Paul Nicholson
--