[CW] ARRL Digital Communications Course

[Donald Chester]

"Digital" is, by definition, a toggling between two states, 1 and zero, with 
no in-between.  That's exactly what cw is - two states, key up and key down. 
  The difference is that the transition is manually controlled, not 
electronically clocked.  But the digital characteristic is what gives cw the 
edge under poor s/n conditions.  Then there is "coherent cw", which is 
digital in every sense of the word.  The key up/key down transition is 
clocked electronically, at an extremely slow sending speed.

In the practical sense with radio transmission, cw does have an analogue 
charcacteristic in the shaping of the keyed waveform to eliminate key 
clicks.  With pure digital cw, the clicks would theoretically have 
infinitely wide sidebands.

Don k4kyv