Date: Mon, 8 Apr 2019 22:44:42 +0200 (CEST)
From: Jacek Lipkowski <sq5bpf@lipkowski.org>
To: rsgb_lf_group@blacksheep.org
Subject: Re: ULF: EbNaut message transmitted from ground loop
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References: <1652663722.1033558.1554575549616.ref@mail.yahoo.com> <1652663722.1033558.1554575549616@mail.yahoo.com> <5CA90E98.2070707@posteo.de> <8c46744b-f60a-ca91-f60f-97a2f5f7b11f@abelian.org> <5CA931D4.6050908@posteo.de> <83eece37-ae11-b2fd-917c-ad29c350695b@abelian.org>
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this is the best i can do:

~$ vtblank -v -a30 -t80  -d0.0008 < pliktmp | vtmult -f 2970.1 | vtresample -r 240 |  vtresample -r 10 | vtraw -oa  | ebnaut  -dp16K21A -r10 -c4 -v -f15 -f16 -M'DK7FC/P' -k16 -S6 -N7

vtblank: selected channel: 1 = -:1
vtblank: channels: 1, sample_rate: 48000
vtblank: hfactor: 0.000e+00
vtblank: afactor: 30.000
carrier phase: -102.8
carrier Eb/N0: -0.9 dB
carrier S/N: 15.09 dB in 133.5 uHz, -23.66 dB in 1Hz, -57.64 dB in 2.5kHz
vtblank: end of input
vtblank: dropsum 0 17485057, nfp 359999999
vtblank: dropfactor 0 4.857e-02

unfortunately i still can't get a decode with -f9

maybe try a few characters less or longer symbols next time.

VY 73

Jacek / SQ5BPF


On Sun, 7 Apr 2019, DK7FC wrote:

> Date: Sun, 07 Apr 2019 17:54:05 +0200
> From: DK7FC <selberdenken@posteo.de>
> Reply-To: rsgb_lf_group@blacksheep.org
> To: rsgb_lf_group@blacksheep.org
> Subject: Re: ULF: EbNaut message transmitted from ground loop
> 
> Jacek,
> 
> 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
> produced
> 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
> 
> 
> 
>