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Date: Tue, 15 Nov 2016 14:50:42 +0100
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Subject: Re: VLF: EbNaut transmissions on lower frequencies?, pre-tests: 6.47kHz
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Hi Paul,

Am 15.11.2016 08:18, schrieb Paul Nicholson:
> Carrier (after phase modulation reversed) in 6uHz bandwidth
>   http://abelian.org/vlf/tmp/161115a.gif
Very nice indeed! :-) I like the very long transmissions. Hopefully the 
phase between day and night is more equal on 5170 Hz and 2970 Hz.

> http://abelian.org/vlf/tmp/161115c.gif
Most impressing. This is something i would call "DFCW-20000", a FFT 
resolution for that mode. But the 15 characters would take several weeks 
in that mode and probably wouldn't even be identifiable during a day 
with high QRN.


Am 14.11.2016 20:09, schrieb Paul Nicholson:
> Start tomorrow with 50 chars? 

Currently i would like to continue with the ongoing daily repetition 
experiment. We are getting most interesting data of the daily path 
stability. So far 4 'events'. For a better statistical certainty i would 
like to get, say, 7 days, one week of coherent adding. We are in the 
comfortable situation to get a daily decode, so we can continue to write 
that table. Some day we may try an attempt to transfer a message that 
will not decode after days, so it would be a better feeling to know from 
our own experiments that we can stay optimistic. An experiment like that 
has not been done (that way) before. So it is good to see what happens 
for a few more days i think.
The recent developed optimism leads us to the imagination that we can 
pass every message length on 46km, as long as the path is stable. We 
will show it!

Currently, RN3AUS is running his setup on VLF, 8270 and 6470. He is 
running a 10 uHz spectrogram. I think i am to weak for that path in that 
BW. Also the path must be stable over the FFT time. But i should give it 
a try! It is also a try to leave a trace at Renato Romero / IK1QFK.

So the plan is to run the experiment (daily repetition) until the 17th, 
15:44 UTC (7 events). Then i will run a carrier for about 2 days without 
an interruption. Then i would start an attempt for the 20 character 
message, which was the mail goal defined in May 2016. And then finally i 
could start the 50 character message to complete the experiments on 6470 
Hz. That is the idea.

BTW it is raining today here. The antenna is detuned a bit and the 
antenna current drops, see 
http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF/TX.png (this link 
always works if i am on air). So the SNR will be lower today. Anyway the 
result will be interesting! Looking forward to that.

73, Stefan

PS: That is an issue for itselfe: If we can assume a LONG path is stable 
in its phase during a certain time, would it be possible to transfer an 
EbNaut message over > 10000 km? We need more stations in higher distances!