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Re: VLF: Using resonance effects of earth-ionosphere for radio experimen

To: <[email protected]>
Subject: Re: VLF: Using resonance effects of earth-ionosphere for radio experiments
From: John Fisher <[email protected]>
Date: Mon, 23 Oct 2017 14:08:25 +0000 (UTC)
Cc: <[email protected]>
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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

Attachment: Earth Ionosphere Waveguide Propagation.jpg
Description: JPEG image

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