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Date: Fri, 19 Mar 2010 18:38:47 +0000
From: Paul Nicholson <vlf0308@abelian.org>
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Subject: Re: VLF: TA, 300m and new PA?
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Jacek wrote:
 > [interference to research] might be not so much of a big
 > problem after all.

I'm inclined to agree.  The ERP is low and should only be a
problem to a research station near to a tx, which could be
dealt with on individual cases.

I should think the lightning locator networks would be affected
least of all - as they are timing pulses, the narrow band CW
should not get in the way.  But they are the tip of the
iceberg.  There is much work going on with whistlers, lightning,
sprites, etc - there is so much still to learn about interaction
between sun, magnetosphere, ionosphere, lightning, weather,
climate, seismic events, etc.  Sensitive instruments operating
at frequencies below 9kHz are important for all of this.

There are already many signals to avoid - power distribution,
navigation and Navy MSK signals.  The latter are a nuisance
because they obliterate whistler nose frequencies at mid
latitudes.  But they have their uses too - strong reliable
signals for detecting ionospheric events.

One difficulty may be that military users might argue that,
if radio amateurs are allowed to transmit, why can't we?
For example, there is sometimes a test signal on VLF, origin
unknown, which moves across a wide range of frequencies above
9kHz.   I have seen it come down to 9.000kHz +/- 0.4Hz and stop
there, obviously respecting the ITU limit.  You can imagine
they would like to go lower if they could get away with it.

Perhaps these concerns amount to nothing - the regulations and
politics are not my field at all!   But personally I would
not like to see conflict between researchers and amateurs.
Having a foot in both camps I can play Devil's advocate in
both directions and it seems to me that technically there need
not be a collision.  (My 'dream' would not be dx records, but
to find a cooperative role).  Hopefully the Bundesnetzagentur
have done their homework and made suitable consultations before
declaring the band 'free'.

But doesn't it seem extraordinary?   No restriction of ERP, mode,
or frequency!  Perhaps amateurs should elect sensible voluntary
limits.  Better for the hobby too, so that all the success is
not taken by a few with largest wallet and garden, and instead
ingenuity, technical skill and determination will be rewarded.

Transmitters and receivers seem not too hard to build.  Success
may boil down to developments in weak signal extraction and
decoding.  One can imagine a contact taking days to complete
with symbol-synchronous or even phase-synchronous signal
processing at each end.  It could turn into a very technical
band.  There might even be developments that have benefit for
underground comms or geological survey. Who knows but it's an
exciting green field in many ways.

Hmm, too much dreaming going on at this end...
--
Paul Nicholson
--