Joe wrote:
> compiled v0.3 but got a bailout 5000 symbols
For some reason, you're still running the earlier version.
ebkey -?
gives you the version. Check the execution path and the
gcc -o option.
> tried 4K19A.
That might be about 3dB too weak.
I made a spectrogram of one of VO1NA's QRP transmissions which
decoded with Eb/N0 = 0.2dB
http://abelian.org/vlf/tmp/151204b.png
That's after the modulation has been reversed to reconstruct
the carrier. There isn't really a lot to see. The carrier
is the intermittent line across the middle at 137.777 kHz and
the bandwidth is that of an information bit. The Viterbi
algorithm manages to pull out 46 bits from the broken line.
The only way to really see the carrier is to plot the spectrum
of the entire 1024 seconds in about 1mHz bandwidth,
http://abelian.org/vlf/tmp/151204c.gif
Spectrograms are popular but they're not really very good
when looking at weak signals and mostly I use spectrum plots.
--
Paul Nicholson
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