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Date: Mon, 25 Sep 2017 15:16:47 +0200
From: DK7FC <selberdenken@posteo.de>
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To: rsgb_lf_group@blacksheep.org
CC: Renato Romero <contact@vlf.it>
References: <15e33e223c2-c04-25a32@webjas-vad091.srv.aolmail.net> <59A6EAF1.1020703@posteo.de> <f9fc93e4-a6e4-fcf1-e665-9de0fcea6d8d@abelian.org> <59A873A1.1090501@posteo.de> <59BEFDB0.5050007@posteo.de>
In-Reply-To: <59BEFDB0.5050007@posteo.de>
Subject: ELF: ZEVS reception from a small loop
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Hi LF friends,

You know, a few weeka ago i've been in France. We had a field day and i 
tested my small loop with its new preamp. Description below.
 From a handy loop with just 0.8 m diameter and 84 turns i didn't expect 
much. However i saw my 4470.005 Hz carrier quite well even in 424 uHz 
FFT bandwidth which is not bad at all for 250 km distance. It even was a 
noisy day.

But now: I reprocessed the recording (which was done by the Raspi and 
vlfrx tools) again, looking for ZEVS on 82 Hz.
To my surprise ZEVS has a very good SNR from that small antenna! It was 
up to 25 dB in 3.8 mHz! That's the celarest signal i saw from ZEVS, so 
far. For the spectrogram i used a 1.5 kHz low pass filter and a noise 
blanker.
See: 
http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF/ZEVS__from_JN29PD06BO.png

So my loop setup seems to be promising for the next 970 Hz experiment as 
well :-)

73, Stefan

PS: The preamp design is taken from: 
http://www.vlf.it/feletti2/idealloop.html


Am 18.09.2017 00:56, schrieb DK7FC:
>
> Am 31.08.2017 22:37, schrieb DK7FC:
>> This weekend i will be in France again, JN29OD96SK 
>> <http://no.nonsense.ee/qth/map.html?qth=JN29OD96SK> , on a field day 
>> with the radio club. I plan to receive the 4470 Hz signal with a 
>> small loop and its new preamp and the octo soundcard. Thus i want to 
>> run a carrier again on 4470.005 Hz. Tomorrow, Friday, i will transmit 
>> the EbNaut message again. After that, the carrier will continue until 
>> sunday. With some luck i hope you can decode the message when 
>> including the friday transmission. If not, i could continue to 
>> transmit on monday...
>
> It took some time but now i have some results from that experiment. I 
> actually placed a 84 turn loop with 0.8 m diameter and a low noise 
> preamp between some trees in France, JN29PD06BO.
> A path of 250 km or 3.7 wavelengths between RX and TX ( 
> http://no.nonsense.ee/qth/map.html?qth=JN29PD06BO&from=jn49ik00wd ). 
> Quite a compact RX system for VLF. I did not prepare the experiment as 
> good as possible, there was no E field RX together with the loop. H 
> field only. It was mainly another test of the octo-soundcard and a 
> first test for the samll loop and its LNA.
> I converted the data files recorded by vlfrx tools into a wav file and 
> analysed it in SpecLab. Here is a wideband spectrogram showing the 
> QRN: http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF/wide4470.png 
> (time markers are incorrect there)
>
> On sunday morning, 3rd Spetember when i looked at the installation i 
> found that the preamp was disconnected from the battery. It must have 
> been an animal walking arround into the field, stumbling over the 
> cable ;-) . Fortunately the interruption took just about one hour ;-)
> Assuming that vlfrx tools correctly resampled to 24 kS/s i run the 
> file into SpecLab set to 47 uHz FFT bin width, hoping to see a 
> trace/peak at 4470.005 Hz.
> And indeed, there is something! See attachment. That's a first trace 
> from DL to F on the 67 km band :-) About 18 dB in 47 uHz during the 
> best time, much more than i expected.
>
> Another success is that i managed to produce a first spectrum peak and 
> generated a png file using vlfrx tools. The procedure is based on 
> Paul's advice. :-)
>
> 73, Stefan
>
>
>
>
>
>
>
>
>
>

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Hi LF friends, <br>
<br>
You know, a few weeka ago i've been in France. We had a field day and i
tested my small loop with its new preamp. Description below.<br>
>From a handy loop with just 0.8 m diameter and 84 turns i didn't expect
much. However i saw my 4470.005 Hz carrier quite well even in 424 uHz
FFT bandwidth which is not bad at all for 250 km distance. It even was
a noisy day.<br>
<br>
But now: I reprocessed the recording (which was done by the Raspi and
vlfrx tools) again, looking for ZEVS on 82 Hz.<br>
To my surprise ZEVS has a very good SNR from that small antenna! It was
up to 25 dB in 3.8 mHz! That's the celarest signal i saw from ZEVS, so
far. For the spectrogram i used a 1.5 kHz low pass filter and a noise
blanker.<br>
See:
<a class="moz-txt-link-freetext" href="http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF/ZEVS__from_JN29PD06BO.png">http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF/ZEVS__from_JN29PD06BO.png</a><br>
<br>
So my loop setup seems to be promising for the next 970 Hz experiment
as well :-)<br>
<br>
73, Stefan<br>
<br>
PS: The preamp design is taken from:
<a class="moz-txt-link-freetext" href="http://www.vlf.it/feletti2/idealloop.html">http://www.vlf.it/feletti2/idealloop.html</a><br>
<br>
<br>
Am 18.09.2017 00:56, schrieb DK7FC:
<blockquote cite="mid:59BEFDB0.5050007@posteo.de" type="cite">
  <meta content="text/html; charset=UTF-8" http-equiv="Content-Type">
  <br>
Am 31.08.2017 22:37, schrieb DK7FC:
  <blockquote cite="mid:59A873A1.1090501@posteo.de" type="cite">
    <meta content="text/html; charset=UTF-8" http-equiv="Content-Type">
    <title></title>
This weekend i will be in France again, <a moz-do-not-send="true"
 href="http://no.nonsense.ee/qth/map.html?qth=JN29OD96SK">JN29OD96SK</a>
, on a field day with the radio club. I plan to receive the 4470 Hz
signal with a small loop and its new preamp and the octo soundcard.
Thus i want to run a carrier again on 4470.005 Hz. Tomorrow, Friday, i
will transmit the EbNaut message again. After that, the carrier will
continue until sunday. With some luck i hope you can decode the message
when including the friday transmission. If not, i could continue to
transmit on monday...<br>
  </blockquote>
  <br>
It took some time but now i have some results from that experiment. I
actually placed a 84 turn loop with 0.8 m diameter and a low noise
preamp between some trees in France, JN29PD06BO.<br>
A path of 250 km or 3.7 wavelengths between RX and TX (
  <a moz-do-not-send="true" class="moz-txt-link-freetext"
 href="http://no.nonsense.ee/qth/map.html?qth=JN29PD06BO&amp;from=jn49ik00wd">http://no.nonsense.ee/qth/map.html?qth=JN29PD06BO&amp;from=jn49ik00wd</a>
). Quite a compact RX system for VLF. I did not prepare the experiment
as good as possible, there was no E field RX together with the loop. H
field only. It was mainly another test of the octo-soundcard and a
first test for the samll loop and its LNA. <br>
I converted the data files recorded by vlfrx tools into a wav file and
analysed it in SpecLab. Here is a wideband spectrogram showing the QRN:
  <a moz-do-not-send="true" class="moz-txt-link-freetext"
 href="http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF/wide4470.png">http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF/wide4470.png</a>
(time
markers are incorrect there)<br>
  <br>
On sunday morning, 3rd Spetember when i looked at the installation i
found that the preamp was disconnected from the battery. It must have
been an animal walking arround into the field, stumbling over the cable
;-) . Fortunately the interruption took just about one hour ;-)<br>
Assuming that vlfrx tools correctly resampled to 24 kS/s i run the file
into SpecLab set to 47 uHz FFT bin width, hoping to see a trace/peak at
4470.005 Hz. <br>
And indeed, there is something! See attachment. That's a first trace
from DL to F on the 67 km band :-) About 18 dB in 47 uHz during the
best time, much more than i expected.<br>
  <br>
Another success is that i managed to produce a first spectrum peak and
generated a png file using vlfrx tools. The procedure is based on
Paul's advice. :-)<br>
  <br>
73, Stefan<br>
  <br>
  <br>
  <br>
  <br>
  <br>
  <br>
  <br>
  <br>
  <br>
  <br>
</blockquote>
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