Nice work.
The 22:00 message Eb/N0 is 13.8dB calculated from the symbol
error rate, but when the decode is used to reverse the
modulation so as to reconstruct a steady carrier, its S/N
corresponds to only Eb/N0 = -3.3dB. Was there a signal on an
adjacent frequency, within the bandwidth of the baseband I/Q but
far enough away from the EbNaut signal not to upset the decode?
Two of the other messages also have suspiciously weak S/N of
the reconstructed carrier.
Adjacent signals wont upset the decoder but will give incorrect
(low) carrier S/N measurements.
The carrier S/N is used to estimate percentage of capacity,
maybe this estimate should instead use the Eb/N0 derived
from the BER so that it's not affected by signals on nearby
frequencies.
There's a big range of signal levels during this QSO, is that
normal for MF? The phase looks pretty steady on these short
messages so I guess the amplitude should be too.
Perhaps you will try some weaker transmissions. Some of the
signals are 3dB to 15dB too strong to be a challenge
for EbNaut, it is not even having to use list decoding.
--
Paul Nicholson
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