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Re: ULF: EbNaut message transmitted from ground loop

To: [email protected]
Subject: Re: ULF: EbNaut message transmitted from ground loop
From: DK7FC <[email protected]>
Date: Sun, 07 Apr 2019 17:54:05 +0200
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I'm right now trying to decode the message from your stream recording. First i did not expect much but a first attempt with
vtread -T2019-04-06_20:25,+125m /jacek | vtcat -p | vtfilter -a th=4 -h bp,f=2970,w=1800 | vtblank -v -a23 -d0.0005 -t100 | vtmult -f2970.1 | vtresample -r240 | vtresample -r10 | vtraw -oa | ebnaut -dp16K21A -r10 -c2 -v -f15 -f16 -M'DK7FC/P' -T0.3 -k16 -S6 -N7
carrier Eb/N0: -1.4 dB
carrier S/N: 14.65 dB in 133.5 uHz

Wow, this already crossed the 14 dB criterium for significant spectrum peaks! A 5 character message would already ecode clearly now!
My data from you has passed a vorbis encode/decode stage, so maybe it is possible for you to get a decode from the raw data?
I'm telling the best result later. We are close to a decode! And that would be a new record distance for amateur radio at ULF.

All this rises new questions about radio propagation because my loop does not at all point into your direction!

73, Stefan

Am 07.04.2019 12:49, schrieb Jacek Lipkowski:
On Sun, 7 Apr 2019, DK7FC wrote:

An OM (OT!) of my radio club told stories of his early radio experiments. He had a friend in some 100m distance and they lay out a small hidden wire into they ground between their QTHs, using the earth as the back 'wire'.

Some electricity (i think they didn't call it electronics back then) hobby books for boys in the USA has descriptions of using ground dipoles for telegraphy. The transmitter was a buzzer-like circuit with step-up transformer, and the receiver was just high impedance headphones. Unfortunately i don't have the book, but i remember it also showed how to make a rhumkorff generator from a ford t ignition coil, so it must have been very old.

I also remember reading somewhere that during the war (not sure it was WW II) using amateur radio equipment was prohibited, and the ARRL advised using similar equipment, so that people don't loose their operating skills.

No doubt some people used much larger ground dipoles than advised in the books :)

VY 73

Jacek / SQ5BPF

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