17.47 kHz DK7FC - VK7/Edgar Ebnaut one-way

[rw3adb]

A successful transmission, on 17470.1 Hz, of a two character EbNaut message was completed on the 10 th September 2018.

The transmitter was at JN49ik, Germany and receiver at QE37pd Tasmania a path of ~ 16786 km (10491 miles).

The message was decoded by processing the signals received on the 8 th and 10 th of September 2018.

The software used was

Spectrum Lab by Wolfgang "Wolf" Buescher  ( https://www.qsl.net/dl4yhf/spectra1.html ) and

EbNaut Coherent BPSK programs, by Paul Nicholson ( http://www.abelian.org/ebnaut/ )

The receiving set-up was a 1 m whip with a FET buffer at 9 m, a Steinberg UR 242 audio interface,

a Garmin GPS unit and Asus notebook.

Thank you to Stefan Schaefer DK7FC for his help and guidance to make this possible, and Wolf and Paul for their excellent software.




Regards, Edgar
Moonah, Tasmania.

P.S. Message re-sent with smaller image

[rw3adb]

 > Not sure if everybody can really understand how weak and
 > buried in noise was that signal ...

1.6 info bits per hour across a 16800 km path, 42% of the
Earth's circumference, using 2mW, much less than the power
of a small LED.

S/N -65 dB in an audio bandwidth.

Not a bad result there, at a range of 183727 American football
stadiums.

Added to http://abelian.org/vlf/amateur-radio/

--
Paul Nicholson
--

[rw3adb]

Edgar, VLF,

My congratulations and respect for your permanent available well working RX system and your patience. When looking back, i remember a number of remarkable achievements we made, also on LF. Great work!
As you say, credits go of course to Wolfgang, Paul and Markus for their great tools and help. Very much has been developed in this decade.

What now? Are 3 characters realistic? We learned that normalizing and stacking can be quite a complex thing and there is that propagation over this path which is not completely predictable and not always reproducable.
I'm going to try 3 characters which needs about 12 dB SNR. But first, some carrier transmissions again...

Roman, i used the inverted L antenna, not the loop. Antenna current was 1.2 A. That's about 320 W and about 23 kV on the antenna, i.e. quite relaxed ;-)

73, Stefan

[rw3adb]

Отчего-то сперва подумал, что Стефан использовал земляную антенну из  дорожного отбойника в этом эксперименте, потому писал в ту тему. потом решил все же уточнить у него, он ответил только сегодня - потому создал отдельную тему посвященную этому эпохальному событию.

[Р1ЩБИ]

42% of the
Earth's circumference, using 2mW, much less than the power
of a small LED.

Впечатляет. Без сравнения звучало бы суховато.

[rw3adb]

42% of the
Earth's circumference, using 2mW, much less than the power
of a small LED.

Впечатляет. Без сравнения звучало бы суховато.

потому и прибил сюда к нам)

[Р1ЩБИ]

потому и прибил сюда к нам)

А может стоит Сергея HGN ссылку на RSGB_LF прикрепить в шапке? Смотрю эту группу на Yahoo, там совсем другие темы, это разные группы или как? Чтот я от жизни совсем отстал.

[rw3adb]

потому и прибил сюда к нам)

А может стоит Сергея HGN ссылку на RSGB_LF прикрепить в шапке? Смотрю эту группу на Yahoo, там совсем другие темы, это разные группы или как? Чтот я от жизни совсем отстал.

их две.
есть на блекшип, есть на яху. потому, что бывало, что блекшип вствала.
я на яху не подписан.
кто поумнее тот создает сразу в двух системах.
я уже давно предлагал открыть тут англоязычный раздел для них всех и пригласить их сюда.
но проблема в том, что кто-то сидит с тлф и через почту ему удобнее.
и потом не у всех у них за границей корректно открывается наш сайт почему-то.
почему я пишу сюда самое важное - не до всех нормально ходит рассылка. и блекшип, и яху. яху вообще весьма глючный портал с кривой кодировкой какой-то. то ли утф8, толь еще какой. помню были проблемы, потому как у большинства все ж вин1251.

[rw3adb]

Here is an update on the ongoing experiment between Edgar and me, trying to pass a 3 character EbNaut message over to VK7 on 17.4701 kHz.

Since the 21st September i'm transmitting the same message with identical parameters, one starts at 16:30 UTC, the other one at 19:30 UTC.
After some days it showed that the first time slot does not develop positively (2 days = +3 dB, 4 days = +6 dB....). The second message was more promising. After 3 days stacked it got up to 9.71 dB SNR. Best result so far:
rank 2673527 ber 4.5833e-01 Eb/N0 -5.3 M -6.947182617e+02 ph 77 150,180,150,180
But this is not really a valid decode because you only get it when knowing the message before and searching explicitely for it.
Yesterday i got the 4th file, today the 5th.
Adding the 4th and 5th file to the stack unfortunately lowers the SNR again.

What now?
There is something to try:
These days the sunset happens about 2 minutes per day earlier. I want to try if it helps to start the transmission 2 minutes earlier per day. Of course this must be considered / compensated when building the stack.
So now i'm continuing to transmit the same messages but the start times will be:
26th: 16:28 and 19:28 UTC
27th: 16:26 and 19:26 UTC
28th: 16:24 and 19:24 UTC

and so on...

We have not been to far away from a valid decode, so let's hope this will help.

Comments or ideas?

73, Stefan