I want to believe but I also suspect that FSK is antiquated analog stuff and that almost everyone has switched to digital encrypted communication nowadays. Anyway if it pans out maybe there is a Nellie Ohr ham radio license connection, since I doubt she bought the equipment purely in pursuit of a hobby, and I also doubt she would be sending or receiving anything in the clear... just thinking out loud...
:^) I just used the 'FSK' term as an example to reinforce 'FS' as a freq shift... 'freq shift' seemed to fit the context, and 'FSK demonstrates the initials are used in tech lingo.
I'm trying to picture Nellie working code at 5wpm. 😜