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Date: Fri, 18 Nov 2016 21:11:02 +0100
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,

Thanks for the daily details and the summary. We or at least i learned a 
lot from the tests.

Probably there would have been a night decode in cumiana if the stream 
would have been available last night.

The night phase between us (Todmorden - Heidelberg) seems to be quite 
stable as well. In average it is about 6 dB weaker. So we need 4 times 
longer to get the same SNR.
Would it makes sense, when we try the longest VLF message ever (it must 
be 75 characters, i found an important message! :-) ), to run day and 
night transmissions? When you assume a known day/night phase shift (28.8 
deg) you could correct that and then add the night signals to the day 
signals. 4 days night+day would then be as good as 5 days day-only, in 
principle. Could be worth to try if there is no result after 4 days.

Since the day/night phase offset is almost constant, does it mean that 
the groundwave phase  and the skywave phase is constant as well? Could 
be assumed from a constant refelction height at night (90km) but i did 
not think that it is so easy.
If night is 6 dB worse than day (simplified perception), is it just due 
to the higher QRN levels or is there some kind of destructive 
interference between skywave and groundwave? If so, this could be 
different on a QTH beeing a few 10 km distant.

Just some thoughts...

What about all the other stations out there, RX and/or TX? Are we alone 
now with our special stuff?

73, Stefan


Am 18.11.2016 18:40, schrieb Paul Nicholson:
>
> Stefan wrote:
>
> > 6 UTC, a carrier starts on 6470.005 Hz, taking 48 hours.
>
>  http://abelian.org/vlf/tmp/161118a.gif
>
> S/N averaging -68.5 dB in 2500Hz, noisier than recent
> daytime tests.  Snowing much of the day here and lots of
> noise on the E-field antenna.
>
> > A test for RN3AUS and IK1QFK and all those taking part in
> > the background.
>
> LWPC predicts the signal in Moscow to be around 48dB below
> 1uV/m, 3dB stronger at night.  Long overland path, over 2000km
> so plenty of attenuation.
>
> Cumiana lost its internet connection last night so no final
> overnight 'TEST' result from there.  Back on since 14:33 today.
>
> Final results of the 'TEST' messages.
>
> Todmorden 881.8 km
> ------------------
>
>  Day test      Eb/N0    S/N   Phase  RMS
>  2016-11-11     3.9    -62.5  141.2  2.56
>  2016-11-12     4.9    -59.7  134.3  2.01
>  2016-11-13     8.5    -55.6  138.5  1.07
>  2016-11-14     3.5    -61.3  136.8  2.48
>  2016-11-15     1.1    -64.0  139.9  3.59
>  2016-11-16     5.0    -60.8  140.8  2.45
>  2016-11-17     3.4    -61.6  152.3  2.87
>
>  11th to 12th   7.5    -57.9  137.1
>  11th to 13th   9.6    -53.8  137.8
>  11th to 14th  10.4    -53.1  137.6
>  11th to 15th  10.7    -52.9  137.8
>  11th to 16th  11.8    -52.3  138.3
>  11th to 17th  11.8    -51.9  139.9
>
>  Night test    Eb/N0    S/N   Phase  RMS
>  2016-11-15    -3.0    -67.8  106.5  5.09   no decode
>  2016-11-16     0.0    -65.5  118.2  4.77   'TEST
>  2016-11-17    -4.1    -69.0  105.8  7.13   no decode
>
>  15th to 16th   1.8    -63.7  113.0         'TEST'
>  15th to 17th   2.5    -62.6  111.1         'TEST'
>
> Todmorden night phase lags day by 28.8 degrees.
>
> Cumiana 507.3 km
> ----------------
>
>  Day test       Eb/N0   S/N   Phase  RMS
>  2016-11-11     -1.7   -66.6   21.9  3.90  no decode
>  2016-11-12     -3.7   -68.6   41.3  4.32  no decode
>  2016-11-13     -7.2   -72.1   51.0  3.81  no decode
>  2016-11-14     -5.2   -70.0   39.2  4.28  no decode
>  2016-11-15     -5.5   -70.4   39.3  6.23  no decode
>  2016-11-16     -0.4   -65.3   31.4  4.78  no decode
>  2016-11-17     -2.3   -67.1   30.1  4.94  no decode
>
>  11th + 12th     0.8  -64.6     30.4  decoded 'TEST'
>  11th to 15th    2.9  -62.5     36.6  decoded 'TEST'
>  11th to 16th    4.6  -60.8     34.3  decoded 'TEST'
>  11th to 17th    4.9  -59.8     34.7  decoded 'TEST'
>
>  Night test      Eb/N0  S/N    Phase  RMS
>  2016-11-15      -5.0  -69.8     2.5  9.88  no decode
>  2016-11-16      -4.5  -69.3     5.1  9.06  no decode
>  2016-11-17      no recording
>  15th + 16th     -1.7  -66.6     3.8        no decode
>
> Cumiana night phase lags day by 30.9 degrees.
>
> -- 
> Paul Nicholson
> -- 
>