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Date: Sat, 14 May 2016 23:55:03 +0200
From: DK7FC <selberdenken@posteo.de>
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In-Reply-To: <57371C03.5040906@posteo.de>
Subject: Re: VLF: EbNaut transmissions on lower frequencies?, pre-tests: 6.47kHz
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Hi Paul, VLF,

Now, i've optimised the resonance a bit and can run 220 mA antenna 
current now! The transductor circuit is still not existing in the system 
so the antenna current may vary a bit. Can be watched at 
http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF/TX.jpg
220 mA is equivalent to -36.5 dB.
Let's try again the same message.

*f = 6470.00000 Hz
Start time: 14.05.2016   21:40:02 UTC
Symbol length: 100 s
Characters: 6
CRC 16
Coding 8K19A
Duration: 15h, 33m, 20s*
*Antenna current: 220 mA

*Not the easiest time in the year but that's the challenge.
As soon as i go to 5.17 kHz we start to dive down the QRN! ;-)

73, Stefan

Am 14.05.2016 14:37, schrieb DK7FC:
> Hi Paul,
>
> Hmm, that's a pity. Maybe it would be useful to run a beacon, 
> periodically the same message in shorter symbols, maybe 40s. A single 
> character would be already fine, like 'R'. This would take 3:33:20 to 
> be sent. I could do this each 4 hours.
> Or i can send a simple carrier for a few days. However i want to build 
> a circuit which keeps the antenna current constant, even during rain, 
> so the ERP stays constant!
>
> 73, Stefan
>
> Am 14.05.2016 12:59, schrieb Paul Nicholson:
>>
>> Stefan wrote:
>>
>> > f = 6470.00000 Hz
>> > Start time: 13.05.2016   00:00:02 UTC
>> > Symbol length: 100 s
>> > Characters: 6
>>
>> I haven't been able to decode this one.   The average noise
>> was 3.7 dB higher than the previous successful message, so
>> there should still be a couple of dB to spare.
>>
>> I've tried a wider range of phase search in case the
>> day/night phase change was more than expected.
>>
>> So far it seems that 6.47 is more variable and unpredictable
>> than 8.27 which is opposite to what I'd expect.
>>
>> -- 
>> Paul Nicholson
>> -- 
>>
>

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Hi Paul, VLF,<br>
<br>
Now, i've optimised the resonance a bit and can run 220 mA antenna
current now! The transductor circuit is still not existing in the
system so the antenna current may vary a bit. Can be watched at
<a class="moz-txt-link-freetext" href="http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF/TX.jpg">http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF/TX.jpg</a><br>
220 mA is equivalent to -36.5 dB.<br>
Let's try again the same message.<br>
<br>
<big><b>f = 6470.00000 Hz<br>
Start time: 14.05.2016   21:40:02 UTC<br>
Symbol length: 100 s<br>
Characters: 6<br>
CRC 16<br>
Coding 8K19A<br>
Duration: 15h, 33m, 20s</b></big><br>
<big><b>Antenna current: 220 mA<br>
<br>
</b><small>Not the easiest time in the year but that's the challenge. <br>
As soon as i go to 5.17 kHz we start to dive down the QRN! ;-)<br>
<br>
73, Stefan<br>
</small></big><br>
Am 14.05.2016 14:37, schrieb DK7FC:
<blockquote cite="mid:57371C03.5040906@posteo.de" type="cite">Hi Paul,
  <br>
  <br>
Hmm, that's a pity. Maybe it would be useful to run a beacon,
periodically the same message in shorter symbols, maybe 40s. A single
character would be already fine, like 'R'. This would take 3:33:20 to
be sent. I could do this each 4 hours.
  <br>
Or i can send a simple carrier for a few days. However i want to build
a circuit which keeps the antenna current constant, even during rain,
so the ERP stays constant!
  <br>
  <br>
73, Stefan
  <br>
  <br>
Am 14.05.2016 12:59, schrieb Paul Nicholson:
  <br>
  <blockquote type="cite"><br>
Stefan wrote:
    <br>
    <br>
&gt; f = 6470.00000 Hz
    <br>
&gt; Start time: 13.05.2016   00:00:02 UTC
    <br>
&gt; Symbol length: 100 s
    <br>
&gt; Characters: 6
    <br>
    <br>
I haven't been able to decode this one.   The average noise
    <br>
was 3.7 dB higher than the previous successful message, so
    <br>
there should still be a couple of dB to spare.
    <br>
    <br>
I've tried a wider range of phase search in case the
    <br>
day/night phase change was more than expected.
    <br>
    <br>
So far it seems that 6.47 is more variable and unpredictable
    <br>
than 8.27 which is opposite to what I'd expect.
    <br>
    <br>
-- <br>
Paul Nicholson
    <br>
-- <br>
    <br>
  </blockquote>
  <br>
</blockquote>
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