Indeed -
What happened to WOLF (*) ?
I've just tried Googling (**) it and find practically no hits. The data mode seems to have been used successfully in the years around 2001 and on, for a bit, but has faded. The URL I had for it is now gives the magic 404. Didn't the first transatlantic contact on 137kHz use this mode?
I guess that as it used 10 baud BPSK, was considered too complicated for the average LF Op. to generate. No one seems to use upconversion from audio, and few seem to be able to make simple PSK encoders. Even for EBnaut, relays are suggested as the means to reverse the phase (yes, truely !!). I suppose, to be fair, 10 baud unfiltered BPSK from a high power transmitter is a bit unkind to other band users.
Andy G4JNT
(*) Weak signal Operation at LF
(**) Other search engines are available - so it has been said.