Message-ID: <5C5C7EF9.2060804@posteo.de>
Date: Thu, 07 Feb 2019 19:54:49 +0100
From: DK7FC <selberdenken@posteo.de>
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To: rsgb_lf_group@blacksheep.org
References: <5C5C5757.5080906@posteo.de>
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Subject: Re: ELF: Carrier on 22.97 Hz
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...wow, after analysing the first 90 minutes of the transmission i found 
that the best SNR is achieved without sferic blanking! So then the hum 
filter and the low pass filter can be disabled too.
So far, during that noisy evening period, i'm getting about *14 dB SNR 
in 185 uHz.*
Unfortunately i temporarely overloaded the PC while doing the analysis, 
which caused an interruption of the stream and then all SpecLab 
instances did a restart.

Now the spectrogram is generated from the unfiltered and unblanked 
stream and now we can already see a clear peak right on the expected 
frequency, showing about 10 dB SNR.

I intend to run the carrier at least for 24 hours, if all works well. 
Not sure if and how the antenna current will drop when it starts to 
rain. It would have been better to decouple the DC component from the 
antenna by using a big series capacitor but id didn't have one that 
holds 20 kV or so.

More later...

73, Stefan


Am 07.02.2019 17:05, schrieb DK7FC:
> Hi ELF ;-)
>
> I'm glad to announce that since 15:46 UTC i am transmitting on ELF 
> (the real ELF, i.e. into the range of 3...30 Hz, ITU radio band 1 
> <https://en.wikipedia.org/wiki/Radio_spectrum#ITU> ) for the first 
> time ever.
>
> Here are the parameters:
>
> TX frequency: *22.970 Hz*
> Wavelength of that frequency: *13060 km*
> Antenna voltage: *4.8 kV rms* (+ a DC component of 7.5 kV)
> Antenna current: *325 uA*
> ERP: 600 aW, or *6E-16 W*
>
> Call it QRP!
> The goal is to detect the signal on my 3.5 km distant tree grabber, 
> whose E field is now working again. Since the E field probe is not to 
> far above the tree, the effective height is not as much as it should 
> ideally be, at this frequency, so the RX is somewhat deaf. Anyway i 
> can see the Schumann resonances and the 60 Hz power grid. So i hope it 
> will work.
>
> A spectrogram which is centered on the frequency of interest in now 
> shown at 
> http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html 
> (3rd window). But maybe 424 uHz FFT bin width is even to optimistic! 
> In a few minutes we'll see more :-) It takes about 40 minutes until a 
> peak could have fully developed...
>
> 73, Stefan
>

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...wow, after analysing the first 90 minutes of the transmission i
found that the best SNR is achieved without sferic blanking! So then
the hum filter and the low pass filter can be disabled too.<br>
So far, during that noisy evening period, i'm getting about <b>14 dB
SNR in 185 uHz.</b><br>
Unfortunately i temporarely overloaded the PC while doing the analysis,
which caused an interruption of the stream and then all SpecLab
instances did a restart.<br>
<br>
Now the spectrogram is generated from the unfiltered and unblanked
stream and now we can already see a clear peak right on the expected
frequency, showing about 10 dB SNR.<br>
<br>
I intend to run the carrier at least for 24 hours, if all works well.
Not sure if and how the antenna current will drop when it starts to
rain. It would have been better to decouple the DC component from the
antenna by using a big series capacitor but id didn't have one that
holds 20 kV or so.<br>
<br>
More later...<br>
<br>
73, Stefan<br>
<br>
<br>
<br>
Am 07.02.2019 17:05, schrieb DK7FC:
<blockquote cite="mid:5C5C5757.5080906@posteo.de" type="cite">
  <meta http-equiv="content-type"
 content="text/html; charset=ISO-8859-15">
Hi ELF ;-)<br>
  <br>
I'm glad to announce that since 15:46 UTC i am transmitting on ELF (the
real ELF, i.e. into the range of 3...30 Hz, <a moz-do-not-send="true"
 href="https://en.wikipedia.org/wiki/Radio_spectrum#ITU">ITU radio band
1</a> ) for the first time ever.<br>
  <br>
Here are the parameters: <br>
  <br>
TX frequency: <b>22.970 Hz</b><br>
Wavelength of that frequency: <b>13060 km</b><br>
Antenna voltage: <b>4.8 kV rms</b> (+ a DC component of 7.5 kV)<br>
Antenna current: <b>325 uA</b> <br>
ERP: 600 aW, or <b>6E-16 W</b><br>
  <br>
Call it QRP!<br>
The goal is to detect the signal on my 3.5 km distant tree grabber,
whose E field is now working again. Since the E field probe is not to
far above the tree, the effective height is not as much as it should
ideally be, at this frequency, so the RX is somewhat deaf. Anyway i can
see the Schumann resonances and the 60 Hz power grid. So i hope it will
work.<br>
  <br>
A spectrogram which is centered on the frequency of interest in now
shown at
  <a moz-do-not-send="true" class="moz-txt-link-freetext"
 href="http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html">http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html</a>
(3rd window). But maybe 424 uHz FFT bin width is even to optimistic! In
a few minutes we'll see more :-) It takes about 40 minutes until a peak
could have fully developed...<br>
  <br>
73, Stefan<br>
  <br>
</blockquote>
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