Hi Jim,
Thanks.
Yes, i actually noticed the the signal was not as stable as expected.
The frequency on the TX side was absolutely stable, as well as the
phase. But on the TX side i saw that the SNR did not rise with the time
as expected (e.g. 3 dB when integrating 2 hours instead of 1 hour). The
noise did not change significantly during that time. I did not expect
this effect on other VLF or ULF frequencoes so far. Unfortunately the
signal is not strong enough to watch the SNR in smaller steps, e.g. in
15 minute segments.
Anyway, i wanted to put a step on that band and i've done it. So now i
can conitune on 970 Hz now which was/is my next goal. I started to
construct a 500 W PA operating on 12 V directly, using 2x 2x IRFP3206
which is no problem on that frequency :-)
73, Stefan
Am 05.09.2018 17:46, schrieb [email protected]:
Stefan,
Excellent news, a great day for ULF!
1570 Hz seems like rough propagation terrain (unpredictable spatial nulls
and temporal phase variations at distances less than 500 km); I wonder if
the earth-loop antenna magnetic field pattern helps with these.
It seems that the rough part of ULF is yielding to your experimental
adjustments and innovation, well done!
Regards,
Jim AA5BW
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of DK7FC
Sent: Wednesday, September 5, 2018 8:51 AM
To: [email protected]
Subject: ULF: First far field detection at 1570 Hz
ULF,
Last sunday i finally managed to detect a carrier transmission on the
191 km band in the far field. In fact the distance is higher than 1/4
wavelength. A new lowest frequency of a signal generated by amateurs,
detected in the far field.
At 250 W RF power i transmitted for 2 hours (starting 08:08 UTC) on my 900m
long ground loop antenna. It seems to be a very hard band with poor
propagation. Furthermore my RX antenna becomes deaf below 2 kHz. So the S/N
is much lower as expected when comparing to the results at 1970 Hz.
Two spectrograms are arrached, showing the short trace in 424 uHz and
212 uHz.
Before finally entering the far field in the frequency range below 1 kHz it
may be necessary to build up an E field RX at the RX QTH. I first step for
that was done yesterday.
To be continued...
73, Stefan
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