Message-ID: <5AAEB091.70709@posteo.de>
Date: Sun, 18 Mar 2018 19:31:45 +0100
From: DK7FC <selberdenken@posteo.de>
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Subject: Re: LF: EbNaut for Dummies (again)
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Hi Luis,

A good idea, very basic.

Am 18.03.2018 18:22, schrieb VIGILANT Luis Fernández:
> There is a text file "sr.txt" you need to configure according to your 
> SpectrumLab settings this way
> https://www.dropbox.com/s/l4ty8yyi2yetaep/SR%20file%20configuration%20explained.bmp?dl=0
>
In the sr.txt file you also need to write the FFT center frequency, like
95998.34 104976 32768 17470.00
> Select the file in the EbNaut decoder and press Run. You will get the 
> real File start at 23:22:41.040
> Then  you need to calculate and set the exact Start offset in EbNaut 
> decoder
> A clock calculator like this is a good help 
> http://www.calculator.net/time-calculator.html
> Anyway you will need to convert the result to seconds. Easy, even for 
> a dummy
>
> Don't forget to increase the CPU number if you are using a multi core 
> processor. Press Run again
> and let the force be with you while the decoder work digging for a 
> signal in that file
>
> Sure I'm missing something here. I think have read there is a 4 sample 
> delay to be added to the offset
> time.
There is also a 0.3 second delay if the TX stations uses SL to transmit 
the VLF signal, like i do.
For the above file start i'm calculating the offset as:
0.3 +4/SR +18.96+7*60

> List lenght is also important, but as a dummy I prefer not to place a 
> finger there at this moment
> Please elaborate and describe how one (dummy) can translate that to 
> seconds.
The list length depends on these transmit parameters, CRC bits, 
polynomial, message length.
There is an optimum list length that can be calculated on Pauls site: 
http://abelian.org/ebnaut/calc.php?
The default list length of 20000 is ok for typical messages in typical 
modes and typical list lengths :-)
But e.g. for messages with a very high CRC, messages beeing very close 
to the limit, or messages as long as 'garden fence' may need a longer 
list length.
On the other side, a 1 character message with CRC0 and list length 20000 
will produce several decodes. So sometimes it is worth to have a look 
for the optimum list length.
For my transmission, the optimum list length is 6485439, much more than 
the default value, due to my very high CRC level.
>
> There is also a lack of lower level explanations about SL here. You 
> must be running sample rate compensation
> from 1pps GPS signal, and the system timing must be accurately set. 
> There is also a relation between FFT
> configuration and file lenght which determines how much transmission 
> time you get in a single file. Depending
> on announced transmission duration it should be modified to fit a 
> complete transmission window
Yes, the important information is the FFT window time. It should cover 
at least the transmission length + the scroll intervall.
>
> So, please go ahead and feel free to complete this basic instructions. 
> And specially ... CORRECT it !
> But always keeping it simple, for us, dummies  ;-)
Hope it is simple enough so far :-)

73, Stefan
>
> 73 de Luis
> EA5DOM
>
>

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Hi Luis, <br>
<br>
A good idea, very basic.<br>
<br>
Am 18.03.2018 18:22, schrieb VIGILANT Luis Fern&aacute;ndez:
<blockquote
 cite="mid:579355A36AEE9D4FA555C45D556003ABA3C369B8@servigilant.vigilant.local"
 type="cite">
  <div
 style="direction: ltr; font-family: Tahoma; color: rgb(0, 0, 0); font-size: 10pt;">
  <span style="font-size: 10pt;">There is a text file "sr.txt" you need
to configure according to your SpectrumLab settings this way</span>
  <div><a moz-do-not-send="true"
 href="https://www.dropbox.com/s/l4ty8yyi2yetaep/SR%20file%20configuration%20explained.bmp?dl=0"
 target="_blank" style="font-size: 10pt;">https://www.dropbox.com/s/l4ty8yyi2yetaep/SR%20file%20configuration%20explained.bmp?dl=0</a></div>
  <div><br>
  </div>
  </div>
</blockquote>
In the sr.txt file you also need to write the FFT center frequency, like<br>
95998.34 104976 32768 17470.00
<blockquote
 cite="mid:579355A36AEE9D4FA555C45D556003ABA3C369B8@servigilant.vigilant.local"
 type="cite">
  <div
 style="direction: ltr; font-family: Tahoma; color: rgb(0, 0, 0); font-size: 10pt;">
  <div>Select the file in the EbNaut decoder and press Run. You will
get the real File start at 23:22:41.040</div>
  <div>Then&nbsp; you need to calculate and set the exact Start offset in
EbNaut decoder</div>
  <div>A clock calculator like this is a good help&nbsp;<span
 style="font-size: 10pt;"><a class="moz-txt-link-freetext" href="http://www.calculator.net/time-calculator.html">http://www.calculator.net/time-calculator.html</a></span></div>
  <div>Anyway you will need to convert the result to seconds. Easy,
even for a dummy&nbsp;</div>
  <div><br>
  </div>
  <div>Don't forget to increase the CPU number if you are using a multi
core processor. Press Run again</div>
  <div>and let the force be with you while the decoder work digging for
a signal in that file</div>
  <div><br>
  </div>
  <div>Sure I'm missing something here. I think have read there is a 4
sample delay to be added to the offset</div>
  <div>time.</div>
  </div>
</blockquote>
There is also a 0.3 second delay if the TX stations uses SL to transmit
the VLF signal, like i do.<br>
For the above file start i'm calculating the offset as:<br>
0.3 +4/SR +18.96+7*60<br>
<br>
<blockquote
 cite="mid:579355A36AEE9D4FA555C45D556003ABA3C369B8@servigilant.vigilant.local"
 type="cite">
  <div
 style="direction: ltr; font-family: Tahoma; color: rgb(0, 0, 0); font-size: 10pt;">
  <div> List lenght is also important, but as a dummy I prefer not to
place a finger there at this moment</div>
  <div>Please elaborate and describe how one (dummy) can translate that
to seconds.</div>
  </div>
</blockquote>
The list length depends on these transmit parameters, CRC bits,
polynomial, message length.<br>
There is an optimum list length that can be calculated on Pauls site:
<a class="moz-txt-link-freetext" href="http://abelian.org/ebnaut/calc.php">http://abelian.org/ebnaut/calc.php</a>?<br>
The default list length of 20000 is ok for typical messages in typical
modes and typical list lengths :-)<br>
But e.g. for messages with a very high CRC, messages beeing very close
to the limit, or messages as long as 'garden fence' may need a longer
list length.<br>
On the other side, a 1 character message with CRC0 and list length
20000 will produce several decodes. So sometimes it is worth to have a
look for the optimum list length.<br>
For my transmission, the optimum list length is 6485439, much more than
the default value, due to my very high CRC level.<br>
<blockquote
 cite="mid:579355A36AEE9D4FA555C45D556003ABA3C369B8@servigilant.vigilant.local"
 type="cite">
  <div
 style="direction: ltr; font-family: Tahoma; color: rgb(0, 0, 0); font-size: 10pt;">
  <div><br>
  </div>
  <div>There is also a lack of lower level explanations about SL here.
You must be running sample rate compensation</div>
  <div>from 1pps GPS signal, and the system timing must be accurately
set. There is also a relation between FFT</div>
  <div>configuration and file lenght which determines how much
transmission time you get in a single file. Depending</div>
  <div>on announced transmission duration it should be modified to fit
a complete transmission window</div>
  </div>
</blockquote>
Yes, the important information is the FFT window time. It should cover
at least the transmission length + the scroll intervall.<br>
<blockquote
 cite="mid:579355A36AEE9D4FA555C45D556003ABA3C369B8@servigilant.vigilant.local"
 type="cite">
  <div
 style="direction: ltr; font-family: Tahoma; color: rgb(0, 0, 0); font-size: 10pt;">
  <div><br>
  </div>
  <div>So, please go ahead and feel free to complete this basic
instructions. And specially ... CORRECT it !</div>
  <div>But always keeping it simple, for us, dummies&nbsp; ;-)</div>
  </div>
</blockquote>
Hope it is simple enough so far :-)<br>
<br>
73, Stefan<br>
<blockquote
 cite="mid:579355A36AEE9D4FA555C45D556003ABA3C369B8@servigilant.vigilant.local"
 type="cite">
  <div
 style="direction: ltr; font-family: Tahoma; color: rgb(0, 0, 0); font-size: 10pt;">
  <div><br>
  </div>
  <div>73 de Luis</div>
  <div>EA5DOM</div>
  <div><br>
  </div>
  <div><br>
  </div>
  </div>
</blockquote>
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