Hi Stefan,
I reduced the size of the second graph and it is attached.
15 kHz is the sweet spot of Earth Ionosphere Waveguide Propagation.
I have a special license for 15.8 kHz and will be doing some transmissions this
winter with 600W.
This frequency range is not used much anymore. The navy communications have
moved up to 19 - 25 kHz.
The TV horizontal frequencies were around here for the old CRT TVs. It should
be easy to get authorization for 15 kHz.
Kind regards,
John
VA3VVV
--------------------------------------------
On Mon, 10/23/17, DK7FC <[email protected]> wrote:
Subject: Re: VLF: Using resonance effects of earth-ionosphere for radio
experiments
To: "[email protected]" <[email protected]>
Received: Monday, October 23, 2017, 9:05 AM
Hi John,
Thank you.
The large image is
well known meanwhile but i did see the other one so
far. Where did you take it from and are there
more informations?
What means ||Tn| ? I
guess n is the numer of hops. But T = Tesla? Not
really. It should be |B(n)|. So maybe something
else. But it would make
sense that is is
something that has to do with the field strength. Odd...
Assuming it is actually the fieldstrength, then
1 kHz looks most
interesting again. I need
to continue to work in that range!!
73, Stefan
Am
23.10.2017 14:21, schrieb John Fisher:
>
Hi Stefan,
>
>
Attached re two graphs on this subject you might find
interesting.
>
> 73
John VA3VVV
>
>
>
>
--------------------------------------------
> On Mon, 10/23/17, DK7FC<[email protected]>
wrote:
>
> Subject:
VLF: Using resonance effects of earth-ionosphere for radio
experiments
> To: [email protected]
> Received: Monday, October 23, 2017,
7:15 AM
>
> Paul,
Markus, VLF,
>
>
Some days ago there have been
> local
thunderstorms near DL0AO in JN59.
>
Two
> images in attachemnt.
> The distance is about
> 225 km. The thunderstorms were on a
small spot only.
>
>
The sferics are clearly
> pronounced
with an SNR increase of 10 dB and
>
more, quite a sharp peak/trace. That's not
> a new observation but now we
> are operating
>
just in that frequency range!
> The
effect
> seems to appear in integer
multiples of about 1.7 kHz, which
>
> is roughly a wavelength of a 180 km,
and
> the earth-ionosphere height
is
> just
>
lambda/2.
>
> It
would be most
> interesting to see how
a similar spectrogram looks from
>
Pauls site (time and date given in the images).
> Is the effect still
> there in 881 km? How
> strong is it expressed. Are the
frequencies the same?
> If so, we
should try to find that region of
>
enhanced propagation, by
> using a
2-tone or
> 3-tone carrier signal. No
problem to provide that from
>
here.
>
> The
> effect is less expressed on 3.4 kHz in
this event. Recently
> we
> discussed about a geometric
single-hop
> path difference between
DK7FC and
> DL0AO
> (Markus calculated 63.3 km difference
between groundwave and
>
> skywave). 5.17 is at a 1.09 lambda
> difference on that path, so
> groundwave and
>
skywave will add constructively. The 3rd order trace of
> the sferic resonance effect is also at
5.1
> kHz!
> 3.4
kHz, or the 88.2 km wave, is then
> at
1.4 lambda difference, so
> skyway
and
> groundwave do not add so
constructive. Maybe this explains
>
> the lower expressed resonance
effect?
>
> It
looks like there can be SNR
>
difference of several dB when changing
> the
> frequency
by just a few 10 Hz, at least arround 5.1 kHz and
> on the
> path to
DL0AO. We should try to
> check
that!
>
> Could
there be
> a frequency with an
advantage on the way to RN3AUS? On a
>
2000 km path the effects will be less
>
expressed. But worth to think about...
>
> 73, Stefan
Earth Ionosphere Waveguide Propagation.jpg
Description: JPEG image
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