Hi VLF,
Today i've improved the reception of my VLF remote reception with the
0.8m diameter loop.
http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html
Quite low QRM levels i find.
I will try to get a trace of ZEVS, you remember? :-)
Still waiting for the GPS module. But maybe i will find the reason for
the occasional phase glitches and can reduce them.
There could have been a faint trace of DJ8WX at 8270.00 Hz, which was
not visible on the city grabber.
Ah, and, today it's the first time i was charging my smartphone onto the
tree!
https://dl.dropboxusercontent.com/u/19882028/MF/20160313_163417.jpg The
Raspi needs 5V anyway and the DC/DC converter is strong enough. So i
simply can switch it in parallel. I constructed a hanger to hold the
phone while it is chared. So i can watch grabber windows out in the
forest. And i can see my incoming spectrograms on VLF by using
Teamviewer remote software. This allows me to align filter components
and gain levels on the VLF preamp
https://dl.dropboxusercontent.com/u/19882028/MF/20160309_152620.jpg :-)
73, Stefan
Am 13.03.2016 23:36, schrieb DK7FC:
Am 11.03.2016 10:06, schrieb Domenico IZ7SLZ:
What about an VLF Ebnaut signal from you ?
73 Domenico, iz7slz
In about 2 weeks i will prepare a small transmit (air cored) coil for
VLF. Markus/DF6NM has been here in Heidelberg a few days ago. He
kindly lent me his yoghurt-cup coil which has > 1 H. I measured 820
Ohm DC resistance but since my antenna C is about 470 pF, i can remove
some of the stacked cups.
The advantage of the coming tests is that i will be able to transmit
under all WX conditions, even in rain and storm! I will also control
the phase of the radiated signal in a feed back loop to compensate
eventual phase changes (thermal variation of L; wire movement in the
wind...). So my signal could be very stable. It is already using 1pps
syncing...
The disadvantage is that i am limited to about 200 mA antenna current.
So the signal will be even 10 dB weaker than in my last experiments
with the large coil. And it is about 30 dB weaker then the kite
experiments signal. An ERP below 100 uW.
We will see if this makes any sense at all. I hope i can leave a
signal on my 3.5 km distant VLF remote grabber then ;-)
Are YOU prepared to monitor traces in 47 uHz FFT BW ("DFCW-60000") ?
This will likely be the mode we can try. In EbNaut it will be most
difficult, maybe when using 100s symbols??
Did you try to monitor the Alpha signals for some days, without seeing
phase glitches except one per day on 0' clock Moscow time?
I'm still struggling to get my VLF remote grabber running on its best
performance using the 0.8m diameter loop.
http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html
73, Stefan
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