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VO1NA<>DK7FC 8270.003 kHz experiment
« : 23 Ноябрь 2019, 23:55:49 »
Splendid work, Stefan! Thanks for the details of what must have been the first
amateur VLF message across the globe.

It seems the VLF TX on this end is behaving itself again, thanks to
your guidance. It was good to have some company from Riccardo on Paul's
spectrograms. A bit of tinkering is still needed here before EbNaut can
be attempted again.

73
Joe VO1NA

On Tue, 12 Nov 2019, DK7FC wrote:

    Свернуть
     Hi Joe,

     Yes, the carrier transmissions were done to get an impression if and when the
     path is stable and if this is reproducable over a few days. I transmitted
     carriers for a few hours and later i tried to decode EbNaut '*' messages with
     different start times and symbol lengths.
     The results were plotted in an Excel sheet (attached) and we found that, when
     stacking 4 days, that a 3 hour long transmission starting at 17.55 UTC would
     give the best SNR of about 12.5 dB. One week later, the situation would be
     different since the path is very dynamic and the sunrise/sunset times are
     changing permanently. It looks a bit weird but in the end we managed to
     decode a 1 char, a 2 char and a 3 character EbNaut message.
     The antenna current was 1.2 A. I had some PA problems, EMC and so on. The
     antenna should have managed 3 dB more signal.
     Meanwhile the special licence for that band expired.

     73, Stefan
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Re: VO1NA<>DK7FC 8270.003 kHz experiment
« Ответ #1 : 03 Январь 2022, 21:43:06 »
Маркус пишет, что принимал Джо не плохо на 8 КГц на днях...

[rsgb-lf-group] VO1NA 8270 Hz
Когда: 2 января в 14:37


Hi Joe, LF,

continuing this thread, here is the data from DL0AO for December 2021. The carrier has been very well visible in our spectrograms.

Happy New Year to all in the group!

73, Markus


Ну и ответ самого Джо:

====================================

Thank-you once again, Markus. The carrier is also very clear in your 47.1 uHz instance, Stefan's VLF spectrogram and Paul's Todmorden RX site. The IQ
data shows the diurnal peaks and their first overtones in the FT (attached). The 2 negative and one positive peak in the imaginary (blue)
component have me curious!

Autumn has changed the aerial impedance -- the current was peaked by
increasing the tuning inductance slightly. Then the back yard thawed during a brief heat wave. The current was peaked this time by putting 1uF in the line to the shed. This is more convenient than going to the shed
to play with the tuning coils.

The tuning was relatively high and stable during the summer. The winter fluctuations are being monitored with a view to automating the tuning,
ideally using the clever ideas of the 'Automatic Tuner' 2000 you posted last year.

In the mean time, the plase is monitored by a scope with the ne07m going to Channel A and Channel B connected to 1 metre of wire tacked
to the shack ceiling. The phase is taken as the distance between the negative to positive transition of the neo7m clock and the peak of the
  sense antenna signal a 75cm wire with 0 phase corresponding to peak aerial current.

Work is ongoing to make a recording phase monitor. An LM324 op amp has done well as a voltage follower for the sense antenna but poorly as a
zero crossing detector for the ne07m: it puts out a trapeziodal wave for some bewildering reason.


73's Joe VO1NA


Маркус прислал тхт с цифирками - прилагаю.
Джо прислал картинку.
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Re: VO1NA<>DK7FC 8270.003 kHz experiment
« Ответ #2 : 04 Январь 2022, 11:47:08 »
С помощью какой программы ведёт наблюдение Маркус?
UB1APE ( RA1ADF) Сергей.

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Re: VO1NA<>DK7FC 8270.003 kHz experiment
« Ответ #3 : 04 Январь 2022, 11:58:44 »
С помощью какой программы ведёт наблюдение Маркус?
EbNaut вроде.
Бывш. Р6ЛДД.

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Re: VO1NA<>DK7FC 8270.003 kHz experiment
« Ответ #4 : 04 Январь 2022, 13:14:06 »
Наверное. А попроще нет ничего?
UB1APE ( RA1ADF) Сергей.

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Re: VO1NA<>DK7FC 8270.003 kHz experiment
« Ответ #5 : 05 Январь 2022, 21:11:35 »
Наверное. А попроще нет ничего?

Увы.
Они там пробили расстояние между Стефаном и Малом G3KEV - что-то ~850 км... Передавали несущую в щрсс-6000.
Но самые ДХ только в Ебнаут возможны.



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