Date: Sat, 5 Aug 2017 08:35:00 -0400
From: Markus Vester <markusvester@aol.com>
To: rsgb_lf_group@blacksheep.org
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In-Reply-To: <59858CB7.3000202@posteo.de>
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Subject: Re: VLF: Carrier on 3675.005 Hz
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Yes the signal is definitely making it to Amberg! This is a fine result of =
mutual collaboration: Stefan DK7FC erecting the transmit facility and posin=
g the low frequency challenge, the DL0AO team (specifically Tom DK1IS and B=
ernd DF9RB) laying out antennas in a quiet forest around their club station=
 and installing dedicated hardware, and myself trying to tame 14 SpecLab in=
stances without introducing too many errors.

The first indication of a 3675.005 Hz peak appeared already a couple of day=
s ago on the E-probe antenna, and is still shown in the ultra-narrow 9.3 uH=
z window (waiting to be updated later tonight). Since yesterday, antenna an=
d GPS connections have been greatly optimized, and the 31 uHz peak appeared=
 early this morning after "only" 9 hours of averaging.=20

Best 73,
Markus (DF6NM)


-----Urspr=C3=BCngliche Mitteilung-----=20
Von: DK7FC <selberdenken@posteo.de>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Verschickt: Sa, 5. Aug 2017 11:17
Betreff: Re: VLF: Carrier on 3675.005 Hz


VLF,=20

 After nearly 8 days the carrier is still on the air without an interruptio=
n, despite occasional thunderstorms :-)
 It looks like the SNR is suffering by summer QRN, as expected.=20

 The stable carrier was good for doing local tests with my Raspi+Octo-sound=
card. The system is now completely configured including system time setting=
 via the GPS module. I recorded a few days from the carrier, converted the =
data files into wav, reprocessed them in SpecLab: The carrier is stable and=
 on the expected frequency, so the sample rate correction via vlfrx tools s=
eems to work.

 Forthermore i corrected some bugs in the circuit of my portable RX loop pr=
eamp for VLF (must have been late in the night when i built it up a few mon=
ths ago). Now the noise is much lower. It looks promising! So it is time fo=
r a portable VLF experiment in the far field, just to check the system more=
 seriously.

The crew of DL0AO has built up and optimised their VLF system to receive th=
e weak 3675.005 Hz carrier in abt 220 km distance. Looks like there is some=
thing on their cardioidal spectrogram pointing to West,=20
http://df6nm.bplaced.net/dl0ao/VLFgrabber/vlfgrabber_dl0ao_test.htm
 Something like 10 dB SNR in 31 uHz. That's not so bad!

 I will run it for some more time until the trace is a bit longer. Then in =
some days i like to start transmitting an EbNaut message on that frequency =
which can be stacked until a decode appears. Markus has developed a tool fo=
r windows to do the stacking, maybe it works in that experiment... It will =
also be a test to see if i can decode the message from my own recording usi=
ng vlfrx tools, an important step to pass...

 So far so good. What are YOUR projects you are currently working on, LF/MF=
/VLF related?

 73, Stefan


 Am 28.07.2017 16:56, schrieb DK7FC:=20
Hi VLF,=20

 I'm back from LF for a while and built up my large VLF coil which was used=
 on 2970 Hz in the beginning of the year. Actually it is under maintenance,=
 one of the six stacks has to be replaced. It is already dismantled but the=
 new wire is not yet wound on the 250 mm diameter PVC tube again.=20
 So now the resonance is higher! I didn't know where it is and just connect=
ed the coil and scanned the frequency downwards. Near 3685 Hz i found a max=
imum of the antenna. Since the Q is not extremely high, i decided to tune t=
o 3675 Hz and added the usual 5 mHz offset, to stay away from multiples of =
1 Hz.=20

 So, now since 14:40 UTC a carrier is running on 3675.005 Hz. The antenna c=
urrent is 170 mA. I estimate the ERP is just 3 uW!

 I guess this is a first amateur radio transmission on the 82 km band and t=
hat class of ERP (?).

 Hopefully the coil will hold the 15.5 kV with just 5 stacks of windings. I=
t's inductance is 3.9 H in the moment!

 I intend to run the carrier for at least a few days, depending on the feed=
back.

 Good luck for the VLF experts!

 73, Stefan

 PS: A 424 uHz RDF spectrogram is running at http://www.iup.uni-heidelberg.=
de/schaefer_vlf/DK7FC_VLF_Grabber2.html (First pixel appears in 30 minutes)
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<div style=3D"font-size:10pt;font-family:arial,helvetica,sans-serif;color:b=
lack;"><div style=3D"color: black; font-family: arial,helvetica,sans-serif;=
 font-size: 10pt;">Yes the signal is definitely making it to Amberg! This i=
s a fine result of mutual collaboration: Stefan&nbsp;DK7FC erecting the&nbs=
p;transmit facility and posing the low frequency challenge, the DL0AO team =
(specifically Tom DK1IS and Bernd DF9RB) laying out antennas in&nbsp;a quie=
t forest around their club station and installing dedicated hardware, and&n=
bsp;myself trying to tame 14 SpecLab instances&nbsp;without introducing too=
 many errors.<br><br>The first indication of a 3675.005 Hz peak appeared al=
ready a&nbsp;couple of&nbsp;days ago on the E-probe antenna, and is still s=
hown&nbsp;in the&nbsp;ultra-narrow 9.3 uHz window (waiting to be updated la=
ter tonight). Since yesterday, antenna&nbsp;and GPS connections have been g=
reatly optimized, and the 31 uHz peak&nbsp;appeared early this morning afte=
r&nbsp;"only" 9 hours of averaging. <br><br>Best 73,<br>Markus (DF6NM)<br><=
br><br>-----Urspr=C3=BCngliche Mitteilung----- <br>Von: DK7FC &lt;selberden=
ken@posteo.de&gt;<br>An: rsgb_lf_group &lt;rsgb_lf_group@blacksheep.org&gt;=
<br>Verschickt: Sa, 5. Aug 2017 11:17<br>Betreff: Re: VLF: Carrier on 3675.=
005 Hz<br><br></div>
<div id=3D"AOLMsgPart_2_ebdb4f12-f32a-4957-b7a9-0934e7937ea2">
<div class=3D"aolReplacedBody" text=3D"#000000" bgcolor=3D"#ffffff">
VLF, <br>
<br>
After nearly 8 days the carrier is still on the air without an
interruption, despite occasional thunderstorms :-)<br>
It looks like the SNR is suffering by summer QRN, as expected. <br>
<br>
The stable carrier was good for doing local tests with my
Raspi+Octo-soundcard. The system is now completely configured including
system time setting via the GPS module. I recorded a few days from the
carrier, converted the data files into wav, reprocessed them in
SpecLab: The carrier is stable and on the expected frequency, so the
sample rate correction via vlfrx tools seems to work.<br>
<br>
Forthermore i corrected some bugs in the circuit of my portable RX loop
preamp for VLF (must have been late in the night when i built it up a
few months ago). Now the noise is much lower. It looks promising! So it
is time for a portable VLF experiment in the far field, just to check
the system more seriously.<br>
<br>
The crew of DL0AO has built up and optimised their VLF system to
receive the weak 3675.005 Hz carrier in abt 220 km distance. Looks like
there is something on their cardioidal spectrogram pointing to West, <br>
<a class=3D"aolmail_moz-txt-link-freetext" href=3D"http://df6nm.bplaced.net=
/dl0ao/VLFgrabber/vlfgrabber_dl0ao_test.htm" target=3D"_blank" rel=3D"noope=
ner noreferrer">http://df6nm.bplaced.net/dl0ao/VLFgrabber/vlfgrabber_dl0ao_=
test.htm</a><br>
Something like 10 dB SNR in 31 uHz. That's not so bad!<br>
<br>
I will run it for some more time until the trace is a bit longer. Then
in some days i like to start transmitting an EbNaut message on that
frequency which can be stacked until a decode appears. Markus has
developed a tool for windows to do the stacking, maybe it works in that
experiment... It will also be a test to see if i can decode the message
from my own recording using vlfrx tools, an important step to pass...<br>
<br>
So far so good. What are YOUR projects you are currently working on,
LF/MF/VLF related?<br>
<br>
73, Stefan<br>
<br>
<br>
Am 28.07.2017 16:56, schrieb DK7FC:
<blockquote cite=3D"about:blank">
 =20
Hi VLF, <br>
  <br>
I'm back from LF for a while and built up my large VLF coil which was
used on 2970 Hz in the beginning of the year. Actually it is under
maintenance, one of the six stacks has to be replaced. It is already
dismantled but the new wire is not yet wound on the 250 mm diameter PVC
tube again. <br>
So now the resonance is higher! I didn't know where it is and just
connected the coil and scanned the frequency downwards. Near 3685 Hz i
found a maximum of the antenna. Since the Q is not extremely high, i
decided to tune to 3675 Hz and added the usual 5 mHz offset, to stay
away from multiples of 1 Hz. <br>
  <br>
So, now <b>since 14:40 UTC</b> a carrier is running on <b>3675.005 Hz</b>.
The
antenna current is <b>170 mA</b>. I estimate the <b>ERP is just 3
uW</b>!<br>
  <br>
I guess this is a first amateur radio transmission on the <b>82 km</b>
band and that class of ERP (?).<br>
  <br>
Hopefully the coil will hold the <b>15.5 kV</b> with just 5 stacks of
windings. It's inductance is <b>3.9 H</b> in the moment!<br>
  <br>
I intend to run the carrier for at least a few days, depending on the
feedback.<br>
  <br>
Good luck for the VLF experts!<br>
  <br>
73, Stefan<br>
  <br>
PS: A 424 uHz RDF spectrogram is running at
  <a class=3D"aolmail_moz-txt-link-freetext" href=3D"http://www.iup.uni-hei=
delberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html" target=3D"_blank" rel=3D"n=
oopener noreferrer">http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF=
_Grabber2.html</a>
(First pixel appears in 30 minutes)<br>
  <br>
</blockquote>


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