"Digimodes"
Thanks JR,
It was digimodes that I had in mind for advanced HF voice comms. I haven't tried that route yet, though I see from RSGB's RadComm that it is becoming popular in amateur circles. and would appear to have serious advantages in "getting through", at least with marginal path loss situations - how this handles high-noise situations such as storms I'm not sure.
Maybe I can look again into hooking my FT857's audio to my computer when I get back from my current trip abroad (if I can keep the computer's broad-spectrum noise out of the radio!)
TKS & 73s
G3OCR