Message-ID: <573E5907.6020107@posteo.de>
Date: Fri, 20 May 2016 02:23:35 +0200
From: DK7FC <selberdenken@posteo.de>
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To: rsgb_lf_group@blacksheep.org
References: <154c32c4dba-373a-24653@webprd-m58.mail.aol.com> <573CAF79.9040701@abelian.org> <573CBBF0.4030701@posteo.de>
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Subject: Re: VLF: EbNaut transmissions on lower frequencies?, pre-tests: 6.47kHz
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A new attempt on 6470 Hz:

*f = 6470.00000 Hz
Start time: 20.05.2016   00:30:02 UTC
Symbol length: 100 s
Characters: 10
CRC 16
Coding 8K19A
Duration: 20h, 53m, 20s*
*Antenna current: 240 mA*

73, Stefan


Am 18.05.2016 21:01, schrieb DK7FC:
> Hi Paul, VLF,
>
> Hmmmm, a pity. I have been optimistic. On the other side it shows that 
> working down there is far from trivial or normal.
> Do you think the phase variations are stronger or rather 
> unpredictable? Some time ago you said the phase changes are no 
> problem. maybe it can be completely different on different days?
> You know, Renato is updating his dreamers band spectrograms. I will 
> run a longer carrier again soon, trying to leave a trace there. Maybe 
> this is helpful for you to get more informations about the phase 
> variations and their reproducability.
>
>
> Markus is crazy, counting psk-ing of the carrier and pixels :-) So the 
> capture of the decoder was a fake (?). At least not a typical decode ;-)
>
> I calibrated the SpecLab plotter to show my antenna current directly 
> in mA in a linear scale and show the image in png format now.
> It is a good feedback for me and decoding stations to check if 
> everything went fine so far: 
> http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF/TX.png
> Only a 3.86 kB file, ideal for regular updating on a smartphone ;-)
>
> 73, Stefan
>
> Am 18.05.2016 20:07, schrieb Paul Nicholson:
>>
>> Stefan wrote:
>>
>> > f = 6470.00000 Hz
>> > Start time: 16.05.2016   21:00:02 UTC
>> > Symbol length: 100 s
>> > Characters: 20
>> > CRC 16
>> > Coding 8K19A
>>
>> I wasn't able to decode the 18 char message.  Thanks to
>> Markus for the sneaky decode, I was able to reverse the
>> modulation to see the signal was 13.6dB in 8.8 uHz.
>>
>> That puts Eb/N0 at about -6.5 dB.
>>
>> Strange, I was expecting a better result because the
>> background noise was quite low throughout the message.
>>
>> Tomorrow I'll have a closer look to try and see if
>> propagation is upsetting the phase.
>>
>> -- 
>> Paul Nicholson
>> -- 
>>
>

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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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A new attempt on 6470 Hz: <br>
<br>
<big><b>f = 6470.00000 Hz<br>
Start time: 20.05.2016   00:30:02 UTC<br>
Symbol length: 100 s<br>
Characters: 10<br>
CRC 16<br>
Coding 8K19A<br>
Duration: 20h, 53m, 20s</b></big><br>
<big><b>Antenna current: 240 mA</b></big><br>
<br>
73, Stefan<br>
<br>
<br>
<br>
Am 18.05.2016 21:01, schrieb DK7FC:
<blockquote cite="mid:573CBBF0.4030701@posteo.de" type="cite">Hi Paul,
VLF,
  <br>
  <br>
Hmmmm, a pity. I have been optimistic. On the other side it shows that
working down there is far from trivial or normal.
  <br>
Do you think the phase variations are stronger or rather unpredictable?
Some time ago you said the phase changes are no problem. maybe it can
be completely different on different days?
  <br>
You know, Renato is updating his dreamers band spectrograms. I will run
a longer carrier again soon, trying to leave a trace there. Maybe this
is helpful for you to get more informations about the phase variations
and their reproducability.
  <br>
  <br>
  <br>
Markus is crazy, counting psk-ing of the carrier and pixels :-) So the
capture of the decoder was a fake (?). At least not a typical decode
;-)
  <br>
  <br>
I calibrated the SpecLab plotter to show my antenna current directly in
mA in a linear scale and show the image in png format now.
  <br>
It is a good feedback for me and decoding stations to check if
everything went fine so far:
<a class="moz-txt-link-freetext" href="http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF/TX.png">http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF/TX.png</a>
  <br>
Only a 3.86 kB file, ideal for regular updating on a smartphone ;-)
  <br>
  <br>
73, Stefan
  <br>
  <br>
Am 18.05.2016 20:07, schrieb Paul Nicholson:
  <br>
  <blockquote type="cite"><br>
Stefan wrote:
    <br>
    <br>
&gt; f = 6470.00000 Hz
    <br>
&gt; Start time: 16.05.2016   21:00:02 UTC
    <br>
&gt; Symbol length: 100 s
    <br>
&gt; Characters: 20
    <br>
&gt; CRC 16
    <br>
&gt; Coding 8K19A
    <br>
    <br>
I wasn't able to decode the 18 char message.  Thanks to
    <br>
Markus for the sneaky decode, I was able to reverse the
    <br>
modulation to see the signal was 13.6dB in 8.8 uHz.
    <br>
    <br>
That puts Eb/N0 at about -6.5 dB.
    <br>
    <br>
Strange, I was expecting a better result because the
    <br>
background noise was quite low throughout the message.
    <br>
    <br>
Tomorrow I'll have a closer look to try and see if
    <br>
propagation is upsetting the phase.
    <br>
    <br>
-- <br>
Paul Nicholson
    <br>
-- <br>
    <br>
  </blockquote>
  <br>
</blockquote>
</body>
</html>

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