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Date: Wed, 18 May 2016 21:01:04 +0200
From: DK7FC <selberdenken@posteo.de>
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Subject: Re: VLF: EbNaut transmissions on lower frequencies?, pre-tests: 6.47kHz
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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
> -- 
>