VO1NA spectrum measured over the VK window 09:45 to 11:30

 http://abelian.org/vlf/tmp/151209a.gif

shows the carrier energy spread evenly across three bins and
the S/N here is 14.5 dB.

A non-coherent sum of three consecutive 476 uHz spectra produces

 http://abelian.org/vlf/tmp/151209b.gif

where the S/N is now around 21 dB.

Plot of carrier phase at an average frequency of 137776.999810 Hz,

 http://abelian.org/vlf/tmp/151209c.gif

There's a few places where the phase seems to step 180 deg and this
is probably where the signal fades out briefly and comes up in
the opposite phase.   If that happens in the middle of an EbNaut
message it will have little chance of decoding.   It might
cope if the phase inversion is near one end or the other.

--
Paul Nicholson
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