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Date: Thu, 07 Dec 2017 21:24:19 +0100
From: DK7FC <selberdenken@posteo.de>
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In-Reply-To: <db1d866c-49c3-1b8d-dcd7-2bc75ee1a414@abelian.org>
Subject: Re: VLF: TA east to west?
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Well, most exciting stuff to read each hour these days.

-4.8 dB is better than i expected. 1 character in a single night is in 
reach! Furthermore i'm running a *carrier with 1.2 A antenna current 
since 19:20 UTC. That's QRO of 1.58 dB.* The wx forecast shows strong 
rain coming closer to Heidelberg. It will rain in a few hours. During 
the carrier transmission in the last days i observed that the current 
drops down by 6 dB in heavy rain. I need the transductor again. A few 
minutes ago i tried to turn the small coil inside the main coil a bit, 
to reduce the L and rise the resonance frequency a bit. Hopefully this 
helps to lower the detuning from the coming rain...

Now, could i do this night? I'm most curious about the message 
detection. I like the whole EbNaut detection process very much, meanwhile.
On the other side i admit that a 24+ hour carrier may be even more 
useful because you can generate a spectrum peak that can give an 
impression about the signal strength (of a 3rd night), and it was 
requested by Markus and Jacek and Jim. With a carrier you can even 
determine the day and night phase and the best time period for a night 
time transmission.
Anyway, it is better to run daytime carriers during the weekends so i 
will start the carrier tomorrow in the evening.
Today i'd like to try that first east to west VLF TA transmission. Let's 
try:

*f = 17470.1000 Hz
Start time: 07.Dec.2017  22:00:00 UTC
Symbol period: 60 s
Characters: 1
CRC bits: 6
Coding 16K21A
Duration: 08:32 [hh:mm]
Antenna current: 1 A*

I just checked that this would be the path to Forest,VA:  
http://k7fry.com/grid/?qth=FM07II52&from=jn49ik00wd

73, Stefan


Am 07.12.2017 18:12, schrieb Paul Nicholson:
>
>
> Ah, ignore the last message.  I just noticed a mistake
> I made with the sample rate!!!
>
> Forest, Virginia gives Eb/N0 = -4.8 dB on the 3 char
> message, which is -37.30 dB in 1Hz.
>
> Only something like 1 in 300 chance of that Eb/N0 with random noise.
> Combining the two results, this is quite likely your signal.
>
> So, this is looking interesting.
>
> -- 
> Paul Nicholson
> -- 
>

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Well, most exciting stuff to read each hour these days.<br>
<br>
-4.8 dB is better than i expected. 1 character in a single night is in
reach! Furthermore i'm running a <b>carrier with 1.2 A antenna current
since 19:20 UTC. That's QRO of 1.58 dB.</b> The wx forecast shows
strong rain coming closer to Heidelberg. It will rain in a few hours.
During the carrier transmission in the last days i observed that the
current drops down by 6 dB in heavy rain. I need the transductor again.
A few minutes ago i tried to turn the small coil inside the main coil a
bit, to reduce the L and rise the resonance frequency a bit. Hopefully
this helps to lower the detuning from the coming rain...<br>
<br>
Now, could i do this night? I'm most curious about the message
detection. I like the whole EbNaut detection process very much,
meanwhile. <br>
On the other side i admit that a 24+ hour carrier may be even more
useful because you can generate a spectrum peak that can give an
impression about the signal strength (of a 3rd night), and it was
requested by Markus and Jacek and Jim. With a carrier you can even
determine the day and night phase and the best time period for a night
time transmission.<br>
Anyway, it is better to run daytime carriers during the weekends so i
will start the carrier tomorrow in the evening.<br>
Today i'd like to try that first east to west VLF TA transmission.
Let's try:<br>
<br>
<b>f = 17470.1000 Hz<br>
Start time: 07.Dec.2017  22:00:00 UTC<br>
Symbol period: 60 s<br>
Characters: 1<br>
CRC bits: 6<br>
Coding 16K21A<br>
Duration: 08:32 [hh:mm] <br>
Antenna current: 1 A</b><br>
<br>
I just checked that this would be the path to Forest,VA: 
<a class="moz-txt-link-freetext" href="http://k7fry.com/grid/?qth=FM07II52&amp;from=jn49ik00wd">http://k7fry.com/grid/?qth=FM07II52&amp;from=jn49ik00wd</a><br>
<br>
73, Stefan<br>
<br>
<br>
<br>
Am 07.12.2017 18:12, schrieb Paul Nicholson:
<blockquote cite="mid:db1d866c-49c3-1b8d-dcd7-2bc75ee1a414@abelian.org"
 type="cite"><br>
  <br>
Ah, ignore the last message.  I just noticed a mistake
  <br>
I made with the sample rate!!!
  <br>
  <br>
Forest, Virginia gives Eb/N0 = -4.8 dB on the 3 char
  <br>
message, which is -37.30 dB in 1Hz.
  <br>
  <br>
Only something like 1 in 300 chance of that Eb/N0 with random noise.
  <br>
Combining the two results, this is quite likely your signal.
  <br>
  <br>
So, this is looking interesting.
  <br>
  <br>
--
  <br>
Paul Nicholson
  <br>
--
  <br>
  <br>
</blockquote>
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