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Re: VLF: Back on 5.17 kHz / 58 km...

To: [email protected]
Subject: Re: VLF: Back on 5.17 kHz / 58 km...
From: DK7FC <[email protected]>
Date: Sun, 15 Jan 2017 22:04:43 +0100
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Am 15.01.2017 20:46, schrieb Paul Nicholson:
Yes I keep thinking about kites.  It sounds like a lot
of fun.
It is! But of course it's effort too. And you need the wind but i can imagine that in north UK you will have enough wind on such a hill, even with a power sled 24.
I've had a powersled 36TT on order from Kiteworld (UK)
since last May, for some reason they don't seem to be
able to send one.   I think that's like the one you
used in 2010 for your first series of VLF experiments.
Mine was without TT.
I'll have to order one direct from Germany.
Oh yes! ;-)
Meanwhile I have a powersled 24 which is quite big
enough.  It flies very steady.   In the UK we are
limited to only 60m height above ground. I am
surrounded by hills of over 100m so I might anchor
the kite at the top of the hill behind the house - if
the wind is right it will be 60m above the anchor and
170m above the house!
Sounds very good. I hope there are no trees on that hill.
But far away from the house you will need a generator which is heavy, so you need a car. QRP in combination with kite antennas is not satisfying i assume. And then, on LF the nights are more promising of course. But then it's dark and cold :-( A piece of land on that hill, with a fence arround it, with a shed and an oven and a generator and some accus as a buffer, and a BIG coil for the band of interest! That's a DREAM! Why didn't we yet see a signal from you if the kite flies steady in the wind? :-) What is missing to come on the air?
>  i tested (again) my new coil for 8270 Hz.

It is a long time since I saw a signal on the 8270Hz
band.   There was a carrier for 2 hours at 8270.002 on
1st Jan 10:20 to 12:20 approx.  Markus?  The last strong
signal was 17th Dec from DJ8WX.
Maybe you will see one in the next hours.
I've been experimenting with changes to the sferic
blanking.  Gained about 1dB at 5170.  Your recent 24 char
daily repeats:

        Was      Now
 10th  -5.8 dB  -4.5 dB (-62.6 dB in 2500Hz)
 11th  -5.3 dB  -4.5 dB
 12th  -4.9 dB  -3.7 dB (-61.8 dB in 2500Hz)
Very interesting! And good that you have some data to experiment with. And a significant improvement! Do you still have the data of my recent transmissions, e.g. the 75 character message on 6470 Hz. Would be interesting to see if less daily transmissions would have been sufficient for a decode. And good to see that there's still more to be gained! Maybe an interesting option for SpecLab? And what about the super-AGC, Markus, Wolf? :-)
The trick is to duplicate the VLF into 2 channels,
one channel triggers the blanker, the other channel
gets the blanking.  Different filter settings on
each channel.   3kHz b/w on the triggering channel,
1kHz b/w on the channel to be blanked.   I think
there's still more to be gained but it takes a long
time to trial all the permutations.
Interesting, i'm looking forward to the end-result.
> i tried to install vlfrx-tools on my Raspi today!

Don't be too disappointed. The USB on RPi is rubbish.
An old laptop would do better.
OK, good to know.
My idea is that i may need more gain in future ULF reception experiments. A loop and an E field receiver, both working on separate soundcards, combined and weighted with vlfrx-tools, to form a cardioid pattern, that could help to gain maybe 6 dB SNR?! But it's probably not an easy task to do that, at least as a beginner...
OK, i'm on the roof again...

73, Stefan

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