Message-ID: <59E505A5.7090800@posteo.de>
Date: Mon, 16 Oct 2017 21:16:53 +0200
From: DK7FC <selberdenken@posteo.de>
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To: rsgb_lf_group@blacksheep.org
References: <15f21bba67d-c15-4e89b@webjas-vaa133.srv.aolmail.net>
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Subject: Re: VLF: Trying the impossible, once more - received by DL0AO and
 DF9RB
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Hi Markus,

Thanks for the summary. Nice results from DL0AO!
Despite your higher QRM i did not expect that the difference in the SNR 
is so high. Your distance to me is even 50 km shorter. But maybe this is 
the reason? Another example for ground/skywave cancellation? At least we 
can see big differences from my signal between day and night at DL0AO. 
Would be nice to have a 30 dB stronger signal, then we could quickly 
check out a certain frequency range to find an optimum...

73, Stefan

Am 15.10.2017 22:31, schrieb Markus Vester:
> Stefan's single character transmission was received well by DL0AO and 
> DF9RB - guess it's ok for everyone to share the decode result now. 
> Note that the export-data from our 31.4 uHz FFTs are slightly shorter 
> than the sequence, producing a little SNR loss. Here are the 
> carrier-based Eb/N0 results:
>
> DL0AO E-W-earthloop in Amberg:
>  date       dB
>  12th       9.4
>  13th      12.1
>  14th      12.8
>  sum      16.0 (three days stacked with equal weighting)
>  sum      16.3 (12th down-weighted by -4.2 dB)
>
> DF9RB urban E-probe in Vilseck:
>  date       dB
>  12th       3.0
>  13th       2.3
>  14th     (no data)
>  sum      4.0  (two days with equal weighting)
>
> The big downer for myself was that nothing at all was received here in 
> Nuremberg. Even after stacking three days (26.7 hours total, 
> equivalent to 10.5 uHz) and undoing the now-known PSK sequence, not 
> the slightest peak appeared in the noise, implying a combined Eb/N0 of 
> less than -7.5 dB. This means that at 6.47 kHz, my E-field 
> antenna with local railway QRM is at least 24 dB worse than the DL0AO 
> earth loop. Pretty hopeless it seems...
>
> Next I will try to look at the nighttime 16 char transmissions in 
> DL0AO data.
>
> Best 73,
> Markus (DF6NM)
>
>
> -----Ursprüngliche Mitteilung-----
> Von: DK7FC <selberdenken@posteo.de>
> An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>;<rd4hu@mail.ru>
> Verschickt: Mi, 11. Okt 2017 17:43
> Betreff: VLF: Trying the impossible, once more
>
> Hi VLF,
>
> The recent 1 character message on 6470 Hz was received at RN3AUS in 
> nearly 2000 km distance, a land path, with very good Eb/N0. 4 
> characters would have been possible. That was a night time transmission.
> Now since a few days there is a SpecLab instance 'listening' on 6470.1 
> Hz at RC4HAA in 2877 km distance (LO53CF) from here, configured for 
> EbNaut reception.
> The daily 16 character night time transmission is still going on, now 
> 6 days are completed. After 4 days, there was no result at RN3AUS and 
> obviously not at SQ5BPF.
>
> So there is some free time for a next experiment during daytime. 
> Stacking EbNaut messages works very well with the tool by DF6NM. So 
> one could try to get a result over many daytime transmissions.
> I have the idea to run a few more single-character transmissions. This 
> is also a good chance for newcomers to get a first decode in EbNaut on 
> VLF.
> With some luck, RN3AUS may decode them over the day time path, as well 
> as SQ5BPF. And with even more luck, a decode at RC4HAA?
> Trying the impossible:
>
> *f = 6470.100000 Hz
> Start time: 12.October.2017  06:00:00 UTC
> Symbol period: 180 s
> Characters: 1
> CRC bits: 0
> Coding 8K19A
> Duration: 9h36min
> Antenna current: 300 mA*
>
> 73, Stefan
>

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Hi Markus, <br>
<br>
Thanks for the summary. Nice results from DL0AO! <br>
Despite your higher QRM i did not expect that the difference in the SNR
is so high. Your distance to me is even 50 km shorter. But maybe this
is the reason? Another example for ground/skywave cancellation? At
least we can see big differences from my signal between day and night
at DL0AO. Would be nice to have a 30 dB stronger signal, then we could
quickly check out a certain frequency range to find an optimum...<br>
<br>
73, Stefan<br>
<br>
Am 15.10.2017 22:31, schrieb Markus Vester:
<blockquote
 cite="mid:15f21bba67d-c15-4e89b@webjas-vaa133.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;">Stefan's
single character transmission was received well by DL0AO and DF9RB -
guess it's ok for everyone to share the decode result now. Note that
the export-data from our 31.4 uHz FFTs are slightly shorter than the
sequence, producing a little SNR loss. Here are the carrier-based Eb/N0
results: </div>
  <div
 style="color: black; font-family: arial,helvetica,sans-serif; font-size: 10pt;"><br>
DL0AO E-W-earthloop in Amberg:<br>
 date       dB<br>
 12th       9.4<br>
 13th      12.1<br>
 14th      12.8<br>
 sum      16.0 (three days stacked with equal weighting)<br>
 sum      16.3 (12th down-weighted by -4.2 dB)</div>
  <div
 style="color: black; font-family: arial,helvetica,sans-serif; font-size: 10pt;"><br>
DF9RB urban E-probe in Vilseck:<br>
 date       dB<br>
 12th       3.0<br>
 13th       2.3<br>
 14th     (no data)<br>
 sum      4.0  (two days with equal weighting)</div>
  <div
 style="color: black; font-family: arial,helvetica,sans-serif; font-size: 10pt;"><br>
The big downer for myself was that nothing at all was received here in
Nuremberg. Even after stacking three days (26.7 hours total, equivalent
to 10.5 uHz) and undoing the now-known PSK sequence, not the slightest
peak appeared in the noise, implying a combined Eb/N0 of less than -7.5
dB. This means that at 6.47 kHz, my E-field antenna with local railway
QRM is at least 24 dB worse than the DL0AO earth loop. Pretty hopeless
it seems...</div>
  <div
 style="color: black; font-family: arial,helvetica,sans-serif; font-size: 10pt;"><br>
Next I will try to look at the nighttime 16 char transmissions in DL0AO
data.</div>
  <div
 style="color: black; font-family: arial,helvetica,sans-serif; font-size: 10pt;"><br>
Best 73,<br>
Markus (DF6NM)<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>;<a class="moz-txt-link-rfc2396E" href="mailto:rd4hu@mail.ru">&lt;rd4hu@mail.ru&gt;</a><br>
Verschickt: Mi, 11. Okt 2017 17:43<br>
Betreff: VLF: Trying the impossible, once more<br>
  <br>
  </div>
  <div id="AOLMsgPart_2_15b4f207-c8bd-4fe4-9940-0172e59ad1ce">
  <div class="aolReplacedBody" text="#000000" bgcolor="#ffffff">Hi VLF,
  <br>
  <br>
The recent 1 character message on 6470 Hz was received at RN3AUS in
nearly 2000 km distance, a land path, with very good Eb/N0. 4
characters would have been possible. That was a night time transmission.<br>
Now since a few days there is a SpecLab instance 'listening' on 6470.1
Hz at RC4HAA in 2877 km distance (LO53CF) from here, configured for
EbNaut reception.<br>
The daily 16 character night time transmission is still going on, now 6
days are completed. After 4 days, there was no result at RN3AUS and
obviously not at SQ5BPF.<br>
  <br>
So there is some free time for a next experiment during daytime.
Stacking EbNaut messages works very well with the tool by DF6NM. So one
could try to get a result over many daytime transmissions.<br>
I have the idea to run a few more single-character transmissions. This
is also a good chance for newcomers to get a first decode in EbNaut on
VLF.<br>
With some luck, RN3AUS may decode them over the day time path, as well
as SQ5BPF. And with even more luck, a decode at RC4HAA?<br>
Trying the impossible: <br>
  <br>
  <b>f = 6470.100000 Hz<br>
Start time: 12.October.2017  06:00:00 UTC<br>
Symbol period: 180 s<br>
Characters: 1<br>
CRC bits: 0<br>
Coding 8K19A<br>
Duration: 9h36min<br>
Antenna current: 300 mA</b><br>
  <br>
73, Stefan<br>
  <br>
  </div>
  </div>
  </div>
</blockquote>
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