From Dave G3YMC

I looked at the information and pictures on the Amrad site of the recent
Nag's Head Dx-pedition today, which I found interesting.  I note however
there is no mention of either the DCF39 signal (138.8) or CFH, the latter at
least I would have expected to be audible there.  Mike G3XDV mentioned this
week that reception of DCF39 must be a good indicator of a possible DX path
to Europe.  However identification of this signal may be the problem as it
is a continuous carrier with periodic bursts of data, and as such would
appear as a solid line on a DSP display.

Yes, but until DCF39 is detected by ear, there is no chance of amateurs
70dB below it getting through, even using slow CW. I, too, was
disappointed that DCF wasn't mentioned. It would be interesting to see a
Spectrogram of the bands 135-137kHz and 137-139kHz using SSB bandwidths
on both the Rx and the DSP. In that bandwidth, Spectrogram will easily
show the modulation bursts.
--
Mike, G3XDV
IO91VT
http://www.dennison.demon.co.uk/activity.htm