Автор Тема: Эксперименты на 8.97 кГц  (Прочитано 45475 раз)

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Re: Эксперименты на 8.97 кГц
« Ответ #150 : 17 Январь 2018, 20:42:22 »
Удалось принять 12-ти символьное сообщение Стефана на 5170.1 Гц. Для этого понадобилось сложить файлы, накопленные за 14 дней:
ebnaut-rx V0.7a
input file C:\EbNaut\DK7FC-12ch-5170\sum_dk7fc — копия.wav
sample rate 0.514403 per second
rx frequency 5170.1
file start time 2018-01-14 14:32:26.360
polynomial 16K21A
crc size 20
number of chars 12
block size 92
symbol period 30.000
number of symbols 1792
list length 20000000
start offset 1660.000
freq offset 0.000000
cores 1
skipped 1660.178234 seconds to start
initial reference phase -10.0
---------------------------------------------
found 73 TO RUSSIA
list rank 898759
reference phase    0    0    0    0
carrier S/N 18.08 dB in 18.6 uHz, -29.23 dB in 1Hz, -63.21 dB in 2.5kHz
carrier Es/N0 -14.46 dB
carrier Eb/N0 -0.27 dB
info bit period 785.96 seconds
symbol error rate 720/1792 = 40.179 %
Es/N0 from symbol errors -15.0 dB
Eb/N0 from symbol errors -0.8 dB
Shannon capacity 6.1 bits/hour
Shannon efficiency 75.1 %
symbols file C:\EbNaut\DK7FC-12ch-5170\sum_dk7fc — копия-symbols.csv
elapsed 159 seconds

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Re: Эксперименты на 8.97 кГц
« Ответ #151 : 07 Октябрь 2018, 17:45:02 »
Стефан принял передачу Рикардо IW4DXW 8270.003 Hz в Ebnaut.


Hi Riccardo,

I also got your 06:30 transmission:

found rank 0 ber 3.9497e-01 Eb/N0 0.9 M -1.385156938e-04 ph 5 150,150,150,150 [IW4DXW]
carrier phase: -3.4 deg
carrier Eb/N0: 0.9 dB
carrier Es/N0: -14.36 dB
carrier S/N: 16.25 dB in 43.4 uHz, -27.37 dB in 1Hz, -61.35 dB in 2.5kHz

73, Stefan



Am 05.10.2018 08:13, schrieb Riccardo:

    Свернуть

    A new transmission is starting at 06:30 UTC.


    73 de Riccardo IW4DXW


    Il Gio 4 Ott 2018, 21:43 Riccardo  ha scritto:

        Свернуть

        Ok, Stefan, thanks. I'm ready:

        Start at 00:00 UTC (5 Oct)
        Coding 16K21A
        CRC 16
        20 sec/sym
        6 char
        Duration 6 h, 24 min

        ...hoping the noise remains low.

        73, Riccardo IW4DXW



Hi Stefan,

Congratulations! It was less of 10 μW.
Thanks for your efforts to decode me. And thanks again to Paul.

The experiment will be portable with a very simple equipment: a 12V 60Ah lead-acid battery (pretty heavy, but i'm considering to buy a LiFePO4 battery pack) and a 200W car audio PA with input connected to a FM RX (QRG in the 70 cm band, no WLAN audio streaming and stuff).
400 meters away, at home, I have the FM TX (500 mW or less) modulated by the PC audio. The feedback for Spectrum Lab will be taken from a little loop (or my main antenna). Do you think that would work?
Tomorrow, wx permitting, I'll measure the impedance of the ground loop.


73 de Riccardo IW4DXW
--_ _ _  _ _ _ --  --_   _   _-_  _--  _ _ _-- _- -_ _ -_ _ _

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Re: Эксперименты на 8.97 кГц
« Ответ #152 : 07 Май 2019, 09:38:56 »
В журнале CQ-QRP N 66 помещена статья "Радиосвязь на частотах ниже 9 кГц"
http://qrp.ru/files/category/15-cqqrp?download=367%3Acq-qrp-66-2019

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Re: Эксперименты на 8.97 кГц
« Ответ #153 : 15 Март 2020, 22:00:41 »
10 лет назад состоялся 2-й VLF эксперимент Стефана DK7FC с использованием антенны 300м, поднятой воздушным змеем.
В рассылке интересные воспоминания Маркуса и Стефана:
Цитировать
Am 15.03.2020 13:57, schrieb Markus (DF6NM) via Groups.Io:
Today is the day! In my eyes, a real breakthrough happened ten years ago, when Stefan did his legendary "second experiment" on March 15, 2010.
 
I remember the day very well. A couple of days before I had set up a narrowband grabber around 8.97 Hz at home in Nürnberg, and we expected that it might be possible to reach a couple of hundred kilometers from the kite antenna. Paul Nicholson also set up a spectrogram in Todmorden. It was a Monday afternoon and I was in the office, fortunately with no scheduled meetings, which allowed me to periodically check the online grabber. Then a small peak started to appear on the right frequency... I immediately called Stefan on his mobile to tell him the good news. When he answered I could her the wind blowing. You can guess how happy he was!

Half an hour later, traces became visible in Todmorden, which really no one had expected. So I called again. This time, I swear Stefan jumped right up, shouting "Mensch das gibts doch nicht!".

The rest is history, and in a way this day has changed what we have been doing with our lives. Fortunately Jacek's archive has all the reflector traffic of that period, still exciting to read:
https://klubnl.pl/rsgb_lf_group-archives/html/rsgb_lf_group/2010-03/msg00171.html
 
Best wishes to all Dreamers,
 
Markus (DF6NM)

Цитировать
Thanks Markus,

Yes, it was an exciting time. When thinking back... Ther was no mobile internet, not PPS stabilized signal generator and i started with DFCW-10 instead of a simple carrier. And it was quite QRP from lead acid accus. Nowadays... So we can see how things develop within 10 years. But now i'm old!
Where is the next generation??! What about your son?

73, Stefan

Действительно, как много достигнуто за эти 10 лет.
И будет ли продолжение?

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Re: Эксперименты на 8.97 кГц
« Ответ #154 : 04 Апрель 2020, 13:12:56 »
Стефан проводит интересный эксперимент: используя "земляную" антенну groundloop (в качестве земляного электрода используется ограждение-отбойник автомобильной дороги; провод длиной около 1100 м проложен в лесу по земле), передает несущую на частоте 8270 Гц непосредственно с ноутбука! Мощность встроенного УНЧ всего 0,6 Вт, ток антенны 75 мА. Тем не менее, сигнал принимается Paul Nicholson! Это 840 км. Письмо Стефана из рассылки:
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Hi VLF friends,

After some problems with software and the antenna, the QRP carrier
transmission seem to run very well now.

The day before yesterday the carrier was interrupted again. But this
time the culprit was not Windows10 but rather by a deer running through
the antenna wire. The wire has been fixed yesterday morning. Later there
was a bad contact in the loop which has been fixed in the afternoon.
Since then, and now, it seems to run very well.

The signal is strong enough in 57.6 km distance to watch the trace with
good S/N in 424 uHz FFT bin widh, see
http://web1.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html
(bottom).

I'm happy. Imagine! The audio output ("speaker") of a tablet computer
connected to a 1130m spaced earth electrode antenna. 0.6 W TX power...
Thinking back to 2010, from that perspective it would have been
considered to be IMPOSSIBLE to detect something on the 36 km band with
real QRP.

The signal is also visible as a weak but stable trace on the right
frequency at DL0AO, QRB = 283 km, see https://vlf.u01.de/VLFgrabber/vlf3.jpg
Oh and now there comes another signal at 8270.01 Hz. Probably this is
DF6NM? Or IW4DXW?

Finally, the QRP signal has also been clearly received by Paul Nicholson
in the UK, at 840 km distance:
http://78.46.38.217/fbins3.html#p=1585983600&b=110&s=fd&m=cardioid&w=r&h=62&z1=0.34&z2=0.64&c=1&mb=637.1666717529297,131.1666717529297,743,194.1666717529297,1
Amazing!

It was worth all the efforts! :-)

It is the first time that i can study local propagation effects. They
seem to be quite expressed. A few times i thought that there is a bad
contact again or even an interruption of the wire. However the signal
was strong on other spectrograms during that time. So it must have been
a groundwave-skywave cancellation. SpecLab is monitoring the antenna
current in the plotter so i can have a look if the antenna current has
been stable during the night.

Later i will announce an EbNaut message transmission but let's see some
more carrier first.

Already thinking about 5.17 kHz in the near future...

73, Stefan

Хотелось бы и мне принять участие в этих экспериментах. Может быть к лету ситуация у нас здесь станет попроще и удастся развернуть приемную позицию на даче...

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Re: Эксперименты на 8.97 кГц
« Ответ #155 : 04 Апрель 2020, 15:29:39 »
То же есть желание  принять участие в экспериментах, по мониторить 8 кГц. В EbNaut, не могу, максимум QRSS.
.-. .- ...-- - - ...

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Re: Эксперименты на 8.97 кГц
« Ответ #156 : 31 Август 2020, 23:29:08 »
Разъяснение как пользоваться ebnaut еще и здесь: http://136.su/index.php/topic,498.msg28893.html#msg28893