PS: I don't want to say that 15 kHz is trivial, not at all. It is all
interesting (except skype!!), 20m, 80, 630m, 2200m, 36km, 46km, 58km,
101km, 309 km and of course also 20 km! :-)
73 and good luck on the mid VLF!!!!!
Stefan
Am 23.10.2017 16:40, schrieb DK7FC:
Hi John,
Yes, like on HF it is a different league to work on 15 kHz or 8.27 kHz
or 2.97 kHz. Working VK from DL in SSB is usually easier on 20m than
on 80m, same for WSPR of course. So one may ask "Why are you trying to
work VK on 80m, 20m is much easier?!"
Some youngsters may even ask "Why are you using radio at all, there is
skype!!?!" :-)
73, Stefan
Am 23.10.2017 16:17, schrieb John Fisher:
Hi Stefan,
Actually, 1 - 4 kHz is the worst frequency range as it is right
between the two waveguide Modes 0 and 1.
ELF around 100 Hz is good for Mode 0 and Mode 1 peaks around 15 kHz.
73 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
|
