Message-ID: <5990112D.3030503@posteo.de>
Date: Sun, 13 Aug 2017 10:43:25 +0200
From: DK7FC <selberdenken@posteo.de>
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To: rsgb_lf_group@blacksheep.org
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Subject: Re: VLF: Carrier on 3675.005 Hz / EbNaut - YES
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Hello Markus and the DL0AO crew,

My congrats, i confirm the message is correct. That's a first message 
detection by radio amateurs on frequencies between 3...4 kHz over such a 
distance.

The phase of that best decode is quite varying. Maybe the phase between 
day and night is changing by more than 120 deg? That could be another 
reason for the unsuccessful 24 hour transmissions...
Let us produce more signals and message decodes to get more impressions 
from that 'new' band: I'm repeating the same message again today. Then 
we can compare the results and you can try stacking both transmissions. 
Later we can try longer stacked messages...


73, Stefan


Am 12.08.2017 23:08, schrieb Markus Vester:
> It looks like we got a valid decode of Stefan's 16 hour 
> transmission from the DL0AO cardioid antenna.
>
> I had also attempted an early decode from a file ending 18:12 UT. This 
> one appeared to be even better (rank 0, +2.2 dB carrier EbN0), perhaps 
> because it ended before the QRN increased.
>
> We had no success with the earlier 24 h transmissions on Aug 10th and 
> 11th, neither single days nor both stacked - surely due to much higher 
> QRN levels than today.
>
> BTW Each decode attempt also produced several false hits with 
> relatively good ranking, so a longer CRC might be preferable.
>
> All the best,
> Markus (DF6NM)
>
>
>
> -----Ursprüngliche Mitteilung-----
> Von: DK7FC <selberdenken@posteo.de>
> An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
> Verschickt: Fr, 11. Aug 2017 15:32
> Betreff: Re: VLF: Carrier on 3675.005 Hz / EbNaut
>
> ...looks like there was no decode from DL0AO from that transmission. 
> It was one of the noisiest days again. I already expected that result 
> and repeated the same message again, running today (24 hours, ending 0 
> UTC). With Markus' tool to stack the resulting files, they could gain 
> 3 dB by stacking these two transmissions.
> Today the noise is much lower. Attached is a RDF spectrogram showing 
> the BPSK as recveived on the tree.
>
> I'm announcing another test, again trying 3 characters, even in a 
> shorter time, avoiding the night time where the SNR is much lower:
>
> *f = 3675.005000 Hz
> Start time: 12.August.2017  04:00:00 UTC
> Symbol period: 80 s
> Characters: 3
> CRC bits: 7
> Coding 16K21A
> Duration: 16h
> Antenna current: 160 mA*
>
>
> 73, Stefan
>
>
>
> Am 09.08.2017 16:48, schrieb DK7FC:
>
>     Hi VLF,
>
>     An attempt for a first message transfer between radio amateurs in
>     the range 3...4 kHz for an expected distance of 226 km, or 2.77
>     wavelengths:
>
>     *f = 3675.005000 Hz
>     Start time: 10.August.2017  00:00:00 UTC
>     Symbol period: 120 s
>     Characters: 3
>     CRC bits: 7
>     Coding 16K21A
>     Duration: 24h
>     Antenna current: 160 mA*
>
>     73, Stefan
>
>

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Hello Markus and the DL0AO crew,<br>
<br>
My congrats, i confirm the message is correct. That's a first message
detection by radio amateurs on frequencies between 3...4 kHz over such
a distance.<br>
<br>
The phase of that best decode is quite varying. Maybe the phase between
day and night is changing by more than 120 deg? That could be another
reason for the unsuccessful 24 hour transmissions...<br>
Let us produce more signals and message decodes to get more impressions
from that 'new' band: I'm repeating the same message again today. Then
we can compare the results and you can try stacking both transmissions.
Later we can try longer stacked messages...<br>
<br>
<br>
73, Stefan<br>
<br>
<br>
<br>
Am 12.08.2017 23:08, schrieb Markus Vester:
<blockquote cite="mid:15dd846ba8e-2e05-13131@webprd-a53.mail.aol.com"
 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;">It
looks like we got a valid decode of Stefan's 16 hour transmission from
the DL0AO cardioid antenna. <br>
  <br>
I had also attempted an early decode from a file ending 18:12 UT. This
one appeared to be even better (rank 0, +2.2 dB carrier EbN0), perhaps
because it ended before the QRN increased.<br>
  <br>
We had no success with the earlier 24 h transmissions on Aug 10th and
11th, neither single days nor both stacked - surely due to much higher
QRN levels than today.<br>
  <br>
BTW Each decode attempt also produced several false hits with
relatively good ranking, so a longer CRC might be preferable.<br>
  <br>
All the best,<br>
Markus (DF6NM)<br>
 <br>
  <br>
  <br>
-----Ursprüngliche 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>
Verschickt: Fr, 11. Aug 2017 15:32<br>
Betreff: Re: VLF: Carrier on 3675.005 Hz / EbNaut<br>
  <br>
  </div>
  <div id="AOLMsgPart_1.2_4c9f935d-521f-4b4b-9357-2fa96a65d6f6">
  <div class="aolReplacedBody" text="#000000" bgcolor="#ffffff">...looks
like there was no decode from DL0AO from that transmission. It
was one of the noisiest days again. I already expected that result and
repeated the same message again, running today (24 hours, ending 0
UTC). With Markus' tool to stack the resulting files, they could gain 3
dB by stacking these two transmissions. <br>
Today the noise is much lower. Attached is a RDF spectrogram showing
the BPSK as recveived on the tree.<br>
  <br>
I'm announcing another test, again trying 3 characters, even in a
shorter time, avoiding the night time where the SNR is much lower:<br>
  <br>
  <b>f = 3675.005000 Hz<br>
Start time: 12.August.2017  04:00:00 UTC<br>
Symbol period: 80 s<br>
Characters: 3<br>
CRC bits: 7<br>
Coding 16K21A<br>
Duration: 16h<br>
Antenna current: 160 mA</b><br>
  <br>
  <br>
73, Stefan<br>
  <br>
  <br>
  <br>
Am 09.08.2017 16:48, schrieb DK7FC:
  <blockquote cite="about:blank"> Hi VLF, <br>
    <br>
An attempt for a first message transfer between radio amateurs in the
range 3...4 kHz for an expected distance of 226 km, or 2.77 wavelengths:<br>
    <br>
    <b>f = 3675.005000 Hz<br>
Start time: 10.August.2017  00:00:00 UTC<br>
Symbol period: 120 s<br>
Characters: 3<br>
CRC bits: 7<br>
Coding 16K21A<br>
Duration: 24h<br>
Antenna current: 160 mA</b><br>
    <br>
73, Stefan<br>
  </blockquote>
  </div>
  </div>
  <br>
  </div>
</blockquote>
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