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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: Thu, 11 Apr 2019 22:44:26 +0200
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Hi Jacek, ULF,

That's great! Amazing! 976 km distance in the ULF range!
A decode at 15.63 dB carrier S/N.
Can you describe your RX antenna and location/position of it?

Thank you for your work! I will try to use your parameters and then we see the digital loss of the vorbis path. It is a good set of data to 'play' with, because this distance/frequency/mode has never been done by radio amateurs before.
A first detection/decode DL > SP.

Eventually i'll do more experiments this weekend. Let's hope for a suitable wx. The last days have not been really quiet ;-)
And BTW, when is your next transmission together with Marcin?

Another thing: Sometimes i git better results when using vtfilter -h lp... -h hp... instead of vtfilter -h bp... because the edges are a bit smoother. Also it can improve the SNR to place the center frequency of the filter not to the TX frequ ency but some 100 Hz up or down, depending on the noise distribution.
73, Stefan

PS: I remember you asked a few times if i can go lower than 5170 Hz. Now we are there :-)


Am 11.04.2019 21:39, schrieb Jacek Lipkowski:
Stefan,

I've tried to bruteforce the right filtering and noise blanking parameters. So after a few thousand tries i get:
[email protected]:/stuff2/sq5bpf/vlf_stefan2$ vtcat -p < stefan_2970_1 |
vtfilter -a th=4 -h bp,f=2970,w=2200 > pliktmp6
[email protected]:/stuff2/sq5bpf/vlf_stefan2$ vtblank -v -d0.0007 -a20 -t
50 < pliktmp6 | vtmult -f 2970.1 | vtresample -r 240 | vtresample
-r 10 |vtraw -oa | ebnaut -dp16K21A -r10 -c2 -v -k16 -S6 -N7 -PS -L
50000
vtblank: selected channel: 1 = -:1
vtblank: channels: 1, sample_rate: 48000
vtblank: hfactor: 0.000e+00
vtblank: afactor: 20.000
initial reference phase -89.4 amplitude 7.496e-04
phase   0    0    0    0    0
vtblank: end of input
vtblank: dropsum 0 64750004, nfp 359999999
vtblank: dropfactor 0 1.799e-01
found rank 14143 ber 4.2548e-01 Eb/N0 -2.5 M -2.143712342e-02 ph 0 0,0,0,0 [DK7FC/P]
carrier phase: -10.6 deg
carrier Eb/N0: -0.4 dB
carrier Es/N0: -15.33 dB
carrier S/N: 15.63 dB in 133.5 uHz, -23.11 dB in 1Hz, -57.09 dB in 2.5kHz
elapsed 92



Hope you like it :)
7 chracters at 976km on ULF 2970.1Hz :)

Article about it here:

https://klubnl.pl/wpr/en/index.php/2019/04/11/ulf-2970hz-record/

BTW i will keep bruteforcing the rx parameters, maybe i will come up with a setting that gives even more S/N. This might be useful for your next tests.

VY 73

Jacek / SQ5BPF







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