Is there anyone in VK equipped to receive coherent? You'll need longer symbols and therefore a longer message duration. Will the phase remain stable for long enough without a GPS lock on the oscillat
Got a good carrier from you http://abelian.org/vlf/fbins.shtml#p=1448996400&b=090&s=sp and this decoded easily in EbNaut using 10 second symbols, eg 8K19A 2 characters, found rank 7: ** ps [ 2 30 30
No way to guess suitable code settings without prior experience or a measurement. I recommend a 3 hour carrier, GPS locked tx and rx to get hopefully a spike on a spectrum in 92 uHz. Measure S/N and
Given a 3 hour VO/VK window, http://abelian.org/ebnaut/calc.php?sndb=15&snbws=92e-6&code=16K21&sp=10&L=1&nc=5&submit=1 http://abelian.org/ebnaut/calc.php?sndb=12.5&snbws=92e-6&code=16K21&sp=12.5&L=1&
... indicates that it takes 4.66 hours for one window. You don't need a spectrogram, just a single 3 hour spectrum. Both ends would need GPSDO and also PPS at the rx soundcard. And even then we don't
I ran last night's signal through vtmatch. First I retrieve 14 hours of signal and mix down to baseband I/Q at 100 samples/sec. vtread -T2015-12-01_19:00,2015-12-02_09:00 /raw | vtmult -f 2777 | # 13
If you have a rubidium oscillator, then use it. But if buying, then I'd suggest a GPSDO because they're often cheaper, you don't have to worry about calibration, and it also gives you a PPS for your
vtmatch passes all its tests now. The next release of vlfrx-tools isn't ready yet but the latest vtmatch is at http://abelian.org/vlf/tmp/vtmatch.c which you can just drop into the build directory an
A plot of the daytime correlation of I/Q against the known encoded message http://abelian.org/vlf/tmp/151204a.gif shows significant spikes with each half-hour message, up to 14:00. Only the first two
At 20:00 and 20:30 I only got carrier. It decoded well with 131 chars and 0.2S symbols, Eb/N0 = 1.7 but no modulation. Looks like ebkey is limited to 5000 symbols and this one needs 6560. I've modifi
I just made a 0.3f with increased limit. It'll probably do something bad with the user interface but the logfile might cope. http://abelian.org/ebnaut/software_ms.shtml -- Paul Nicholson --
For some reason, you're still running the earlier version. ebkey -? gives you the version. Check the execution path and the gcc -o option. That might be about 3dB too weak. I made a spectrogram of on
Joe, Copied your 131 char 4K19A 0.2S 21:00 message fine, Eb/N0=7.2 and I think that's a record for message length but not for capacity. -- Paul Nicholson --
Something taking up your RAM, the decoder needs 3.8 Gbytes for this one which should fit ok. The 4K19A 0.2S signal is much stronger than I expected and decodes easily with uniform phase. We're stret
The timing of these 0.2S messages appears to be spot on, I'm getting about a 10mS lag which would be roughly the propagation delay. So far, VO1NA 2015-12-04/05 4K19A 0.2S 131C QRO start Eb/N0 BER ran
Yes a huge signal tonight in Europe from VO1NA. I'll leave it to you guys to choose a frequency. VO1NA 2015-12-04/05 4K19A 0.2S 131C QRO start Eb/N0 BER rank 22:00 7.2 5.7% 0 22:30 7.0 6.2% 0 23:00 4
How about a daytime test with, as a starting point, say Message: VO1NA Chars: 5 Symbols: 5 seconds Coding: 16K21A Duration: 5280 seconds, 01:28:00.00 -- Paul Nicholson --
Looks like I chose about the right settings for daytime: found rank 10968: VO1NA ps [ 2 30 30 30 30] re-encode 425/1056 ber 4.02e-01 Es/N0=-15.1 Eb/N0=0.4 and the phase appears steady for the 90 minu
