Stefan's
single character transmission was received well by DL0AO and DF9RB -
guess it's ok for everyone to share the decode result now. Note that
the export-data from our 31.4 uHz FFTs are slightly shorter than the
sequence, producing a little SNR loss. Here are the carrier-based Eb/N0
results:
DL0AO E-W-earthloop in Amberg:
date dB
12th 9.4
13th 12.1
14th 12.8
sum 16.0 (three days stacked with equal weighting)
sum 16.3 (12th down-weighted by -4.2 dB)
DF9RB urban E-probe in Vilseck:
date dB
12th 3.0
13th 2.3
14th (no data)
sum 4.0 (two days with equal weighting)
The big downer for myself was that nothing at all was received here in
Nuremberg. Even after stacking three days (26.7 hours total, equivalent
to 10.5 uHz) and undoing the now-known PSK sequence, not the slightest
peak appeared in the noise, implying a combined Eb/N0 of less than -7.5
dB. This means that at 6.47 kHz, my E-field antenna with local railway
QRM is at least 24 dB worse than the DL0AO earth loop. Pretty hopeless
it seems...
Next I will try to look at the nighttime 16 char transmissions in DL0AO
data.
Hi VLF,
The recent 1 character message on 6470 Hz was received at RN3AUS in
nearly 2000 km distance, a land path, with very good Eb/N0. 4
characters would have been possible. That was a night time transmission.
Now since a few days there is a SpecLab instance 'listening' on 6470.1
Hz at RC4HAA in 2877 km distance (LO53CF) from here, configured for
EbNaut reception.
The daily 16 character night time transmission is still going on, now 6
days are completed. After 4 days, there was no result at RN3AUS and
obviously not at SQ5BPF.
So there is some free time for a next experiment during daytime.
Stacking EbNaut messages works very well with the tool by DF6NM. So one
could try to get a result over many daytime transmissions.
I have the idea to run a few more single-character transmissions. This
is also a good chance for newcomers to get a first decode in EbNaut on
VLF.
With some luck, RN3AUS may decode them over the day time path, as well
as SQ5BPF. And with even more luck, a decode at RC4HAA?
Trying the impossible:
f = 6470.100000 Hz
Start time: 12.October.2017 06:00:00 UTC
Symbol period: 180 s
Characters: 1
CRC bits: 0
Coding 8K19A
Duration: 9h36min
Antenna current: 300 mA
73, Stefan
