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Date: Fri, 04 Nov 2016 14:00:16 +0100
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Subject: Re: VLF: EbNaut transmissions on lower frequencies?, pre-tests: 6.47kHz
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Hi Paul,

Am 04.11.2016 07:52, schrieb Paul Nicholson:
>
> http://abelian.org/vlf/tmp/161102b.gif
A few more thoughts:
-The error density is not really higher during times of higher noise. So 
the SNR may be as good as in daylight? Time for a night-transmission test!
-There are short periods in which the error density is very high, it's 
RED!! Probably this is the Terminator (II) which passes to that time 
between our path and that misterious 46 km band? How many terminators 
are there? And when do they pass?
- I find it interesting to focus on errors rather than on the actual 
signal :-) They also contain relevant information to study the band over 
our path.

> Difference between success and failure is only a few bits, eg
>
>  Eb/N0 = +1.7 dB  bit error rate = 501/1312  Virtually certain decode
>  Eb/N0 = -0.2 dB  bit error rate = 531/1312  ~95% chance
>  Eb/N0 = -0.5 dB  bit error rate = 535/1312  ~80% chance
>  Eb/N0 = -1.0 dB  bit error rate = 541/1312  ~50% chance
>  Eb/N0 = -1.7 dB  bit error rate = 551/1312  Almost no chance
Very interesting. It helps to better understand what a successful decode 
depends on.

> Still working on 2016-11-03 06:00 16K25A S30 C11, so far no decode
> but a couple of settings remain to try.
Good luck for us!

It's a bit a pity that the phase varies so much between day and night. I 
would have fun to try a message with 1000 second symbols and 20 
characters. Even if they take 2 weeks, no problem!

Ah, and another thing: Did you ever see a frequency offset or (relevant) 
time offset on my transmissions. If so, it would be useful to get a 
feedback.

73, Stefan
>
> -- 
> Paul Nicholson
> -- 
>