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Date: Tue, 26 Sep 2017 00:05:42 +0200
From: DK7FC <selberdenken@posteo.de>
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Subject: Re: ELF: ZEVS reception from a small loop
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Hi Markus,

Am 25.09.2017 17:03, schrieb Markus Vester:
> Have you also tried to look for Schumann resonances in the recording?
I tried but saw nothing. So either the signal level from the loop is to 
small (i think so) and/or the frequency response of the preamp also 
contributes.
>
> Instead of the 84 turns, you could probably employ a single turn loop 
> with a transformer. So perhaps your antenna in the tree might receive 
> ELF as well?
You know, on the tree i'm using a single turn loop and a ferrite 
transformer with 100 turns secondary. But the preamp was designed for a 
low power consumption. The LT1028 must run from the 12 V level, 5 V is 
not enough. VLF was a rather low priority during the time i built the 
preamp.

BUT: You may have noticed some interruptions on the grabber yesterday. 
This happend because i set up a new firmware on the Raspi (now Linux 8 / 
Jessie). vlfrx tools is also installed already. I want to observe if the 
new system is running stable, then i consider to install one of the octo 
soundcards there. And then i could run 2 channels for MF and 3 channels 
for VLF and 1 channel for PPS. If i do so, i would need a new preamp 
anyway. And then i can watch the E field from there too. But that will 
take time...

73, Stefan

>
> Best 73,
> Markus
>
> -----UrsprĂźngliche Mitteilung-----
> Von: DK7FC <selberdenken@posteo.de>
> An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
> Cc: Renato Romero <contact@vlf.it>
> Verschickt: Mo, 25. Sept 2017 15:18
> Betreff: ELF: ZEVS reception from a small loop
>
> 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
>     <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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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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Hi Markus,<br>
<br>
Am 25.09.2017 17:03, schrieb Markus Vester:
<blockquote
 cite="mid:15eb990d1e5-c02-28ac5@webjas-vaa005.srv.aolmail.net"
 type="cite">
  <div
 style="font-size: 10pt; font-family: arial,helvetica,sans-serif; color: black;">
  <div
 style="color: black; font-family: arial,helvetica,sans-serif; font-size: 10pt;">Have
you also tried to look forÂ Schumann resonances in the recording?<br>
  </div>
  </div>
</blockquote>
I tried but saw nothing. So either the signal level from the loop is to
small (i think so) and/or the frequency response of the preamp also
contributes.<br>
<blockquote
 cite="mid:15eb990d1e5-c02-28ac5@webjas-vaa005.srv.aolmail.net"
 type="cite">
  <div
 style="font-size: 10pt; font-family: arial,helvetica,sans-serif; color: black;">
  <div
 style="color: black; font-family: arial,helvetica,sans-serif; font-size: 10pt;"><br>
Instead of the 84 turns,Â you couldÂ probably employ a single turn loop
with a transformer. SoÂ perhaps your antennaÂ in the tree mightÂ receive
ELF as well?<br>
  </div>
  </div>
</blockquote>
You know, on the tree i'm using a single turn loop and a ferrite
transformer with 100 turns secondary. But the preamp was designed for a
low power consumption. The LT1028 must run from the 12 V level, 5 V is
not enough. VLF was a rather low priority during the time i built the
preamp. <br>
<br>
BUT: You may have noticed some interruptions on the grabber yesterday.
This happend because i set up a new firmware on the Raspi (now Linux 8
/ Jessie). vlfrx tools is also installed already. I want to observe if
the new system is running stable, then i consider to install one of the
octo soundcards there. And then i could run 2 channels for MF and 3
channels for VLF and 1 channel for PPS. If i do so, i would need a new
preamp anyway. And then i can watch the E field from there too. But
that will take time...<br>
<br>
73, Stefan<br>
<br>
<blockquote
 cite="mid:15eb990d1e5-c02-28ac5@webjas-vaa005.srv.aolmail.net"
 type="cite">
  <div
 style="font-size: 10pt; font-family: arial,helvetica,sans-serif; color: black;">
  <div
 style="color: black; font-family: arial,helvetica,sans-serif; font-size: 10pt;"><br>
Best 73,<br>
Markus<br>
  <br>
-----UrsprĂźngliche Mitteilung----- <br>
Von: DK7FC <a class="moz-txt-link-rfc2396E" href="mailto:selberdenken@posteo.de">&lt;selberdenken@posteo.de&gt;</a><br>
An: rsgb_lf_group <a class="moz-txt-link-rfc2396E" href="mailto:rsgb_lf_group@blacksheep.org">&lt;rsgb_lf_group@blacksheep.org&gt;</a><br>
Cc: Renato Romero <a class="moz-txt-link-rfc2396E" href="mailto:contact@vlf.it">&lt;contact@vlf.it&gt;</a><br>
Verschickt: Mo, 25. Sept 2017 15:18<br>
Betreff: ELF: ZEVS reception from a small loop<br>
  <br>
  </div>
  <div id="AOLMsgPart_2_6c0e22fe-daff-417e-b45f-c86fe32039dc">
  <div class="aolReplacedBody" text="#000000" bgcolor="#ffffff">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 moz-do-not-send="true" class="aolmail_moz-txt-link-freetext"
 href="http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF/ZEVS__from_JN29PD06BO.png"
 target="_blank" rel="noopener noreferrer">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 moz-do-not-send="true" class="aolmail_moz-txt-link-freetext"
 href="http://www.vlf.it/feletti2/idealloop.html" target="_blank"
 rel="noopener noreferrer">http://www.vlf.it/feletti2/idealloop.html</a><br>
  <br>
  <br>
Am 18.09.2017 00:56, schrieb DK7FC:
  <blockquote cite="about:blank"> <br>
Am 31.08.2017 22:37, schrieb DK7FC:
    <blockquote cite="about:blank"> This weekend i will be in France
again, <a moz-do-not-send="true"
 href="http://no.nonsense.ee/qth/map.html?qth=JN29OD96SK"
 target="_blank" rel="noopener noreferrer">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="aolmail_moz-txt-link-freetext"
 href="http://no.nonsense.ee/qth/map.html?qth=JN29PD06BO&amp;from=jn49ik00wd"
 target="_blank" rel="noopener noreferrer">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="aolmail_moz-txt-link-freetext"
 href="http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF/wide4470.png"
 target="_blank" rel="noopener noreferrer">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>
  </div>
  </div>
  </div>
</blockquote>
</body>
</html>

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