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

[Markus Vester <markusvester@aol.com>]

No need for Paul to stay in the cold all night... I guess the idea is to raise the kite to 60 m slant altitude above the anchor point, and let the antenna wire drop 170 m downwards (sic!) from there, straight to the house ;-) 

The signal on Jan 1st wasn't mine. My last VLF transmissions were Oct 1st and Oct 30, both pure carrier on 8270.0025 and still visible in the Todmorden spectrogram history. A somewhat stronger signal was radiated from a balloon on July 19.

Lacking sensitivity on lower frequencies, my poor grabber has been starving. So we're looking forward to Stefan trying his new coil. 

All the best,
Markus (DF6NM)


-----Ursprüngliche Mitteilung-----
Von: DK7FC <selberdenken@posteo.de>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Verschickt: So, 15 Jan 2017 10:07 pm
Betreff: Re: VLF: Back on 5.17 kHz / 58 km...

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