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Date: Mon, 16 May 2016 22:50:04 +0200
From: DK7FC <selberdenken@posteo.de>
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In-Reply-To: <57395CE6.5040208@abelian.org>
Subject: Re: VLF: EbNaut transmissions on lower frequencies?, pre-tests: 6.47kHz
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Hi Paul, VLF,

A spontaneous impulse/idea:

Let's be optimistic and try the long message in 100s symbols. The 
announcement happens a few minutes before the start of the transmission :-)

*f = 6470.00000 Hz
Start time: 16.05.2016   21:00:02 UTC
Symbol length: 100 s
Characters: 20
CRC 16
Coding 8K19A
Duration: 34h, 13m, 20s*
*Antenna current: 240 mA*

16K25A and 200s, that's a job for the lower frequencies. I have to send 
the mail now, otherwise it comes to late ;-)

73, Stefan

Am 16.05.2016 07:38, schrieb Paul Nicholson:
>
> Stefan wrote:
>
> > would you think that going from 100s to 200s will improve
> > things by about 3 dB?
>
> Yes, or better: keeping to 100s and going to a 16K mode instead
> of 8K for an increase of coding gain.
>
> > How long do you record the VLF soundcard stream?
>
> About 65 months at the moment.
>
> > Would it be possible, for example, to transmit a 1 week long
> > message, without an announcement before the start?
>
> Yes, in principle.  The longer the message the more chance of
> a battery problem or sheep knocking down one of the antennas,
> or thunderstorm or power cut, or one of the cats sleeping on
> top of the GPS antenna.
>
> But with a long message, an interruption of a few hours is
> not a disaster.  After a power cut, my rx will restart with
> the same reference phase and continue recording so there will
> be a gap but no loss of phase.
>
> We may have to put this to use when we reach ULF.
>
> Un-announced is ok because of the continuous recording but better
> to announce if possible so that I know not to do maintenance
> (or tests with kites! Will be playing with the Power Sled 24).
>
> -- 
> Paul Nicholson
> -- 
>

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Hi Paul, VLF,<br>
<br>
A spontaneous impulse/idea:<br>
<br>
Let's be optimistic and try the long message in 100s symbols. The
announcement happens a few minutes before the start of the transmission
:-)<br>
<br>
<big><b>f = 6470.00000 Hz<br>
Start time: 16.05.2016   21:00:02 UTC<br>
Symbol length: 100 s<br>
Characters: 20<br>
CRC 16<br>
Coding 8K19A<br>
Duration: 34h, 13m, 20s</b></big><br>
<big><b>Antenna current: 240 mA</b></big><br>
<br>
16K25A and 200s, that's a job for the lower frequencies. I have to send
the mail now, otherwise it comes to late ;-)<br>
<br>
73, Stefan<br>
<br>
Am 16.05.2016 07:38, schrieb Paul Nicholson:
<blockquote cite="mid:57395CE6.5040208@abelian.org" type="cite"><br>
Stefan wrote:
  <br>
  <br>
&gt; would you think that going from 100s to 200s will improve
  <br>
&gt; things by about 3 dB?
  <br>
  <br>
Yes, or better: keeping to 100s and going to a 16K mode instead
  <br>
of 8K for an increase of coding gain.
  <br>
  <br>
&gt; How long do you record the VLF soundcard stream?
  <br>
  <br>
About 65 months at the moment.
  <br>
  <br>
&gt; Would it be possible, for example, to transmit a 1 week long
  <br>
&gt; message, without an announcement before the start?
  <br>
  <br>
Yes, in principle.  The longer the message the more chance of
  <br>
a battery problem or sheep knocking down one of the antennas,
  <br>
or thunderstorm or power cut, or one of the cats sleeping on
  <br>
top of the GPS antenna.
  <br>
  <br>
But with a long message, an interruption of a few hours is
  <br>
not a disaster.  After a power cut, my rx will restart with
  <br>
the same reference phase and continue recording so there will
  <br>
be a gap but no loss of phase.
  <br>
  <br>
We may have to put this to use when we reach ULF.
  <br>
  <br>
Un-announced is ok because of the continuous recording but better
  <br>
to announce if possible so that I know not to do maintenance
  <br>
(or tests with kites! Will be playing with the Power Sled 24).
  <br>
  <br>
--
  <br>
Paul Nicholson
  <br>
--
  <br>
  <br>
</blockquote>
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