Stefan,
I've tried to bruteforce the right filtering and noise blanking
parameters. So after a few thousand tries i get:
sq5bpf@jitter:/stuff2/sq5bpf/vlf_stefan2$ vtcat -p < stefan_2970_1 | vtfilter -a
th=4 -h bp,f=2970,w=2200 > pliktmp6
sq5bpf@jitter:/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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