Jacek wrote:

> we went from joy because we were able to decode a simple carrier
> from a high power transmission using a kite antenna, to decoding
> multi-character medium-power transmissions with ease.

I was thinking just the same thing recently.   When you look back,
VLF has come a long way in the last seven years.

Here is the first sign of an amateur VLF signal received at
Todmorden, 15th March 2010,

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

It was actually a very strong signal, 20dB stronger than we
routinely use today.   But at the time it was not entirely
certain that this was a genuine signal and not some artifact
or interference.  That's why the title doesn't mention DK7FC.
It took a bit of work to be sure of it.

After many years of listening to natural radio at VLF it was
quite a novelty to pick up an amateur radio signal!

Two things are interesting to note.

One is that Stefan's kite experiment could have been done 20 or
more years earlier.   I don't think we used any technology or
knowledge that wasn't available in say 1990, or even 1985.
It just needed somebody to go out there and try it.

The other thing is that, although the art has been developed
greatly since then, I don't think anything new has been invented.
We've just pulled in whatever existing technology appears useful.
There are no break-through antenna designs or marvelous new DSP
algorithms.

It makes you wonder what else is out there, just waiting to
be tried for the first time.

--
Paul Nicholson
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