When you say "machine" modes, are you meaning CW decoded by software or
by the brain (be it aurally or visually) ? There is a profound

difference...

73,
Alberto    I2PHD

By "machine" modes, I mean anything which requires a PC or other
hard/software to change the raw CW+QRM/QRN audio input into something which
can be interpreted by human senses (usually involving translating the signal
from audible to visible form). This is in contrast to direct aural decoding
of CW by the brain, filter-assisted or otherwise, which generally requires a
lot more human "processing power".

Apart from the obvious i.e. the various decoders with text output, I would
put software such as Spectran (VY NICE program, by the way!), Spectrogram,
etc. in the "machine modes" category. This is because it takes a wanted
audio signal which is buried in QRM/QRN and therefore indistinguishable, and
translates it into a visual form, separating it from the unwanted stuff as a
discrete trace on a screen. The only part the brain is required to play in
this process is to interpret the trace as letters and numbers - most of the
hard work has been done already.

Hope this explanation is reasonably coherent!

Regards

Kevin, G1HDQ.