N2EY wrote:

"S" is one time unit on, one time unit off, one time unit on, one
time unit
off, one time unit on. Then at least three time units off.

"O" is three time units on, one time unit off, three time units on,
one time
unit off, three time units on. Then at least three time units off.

The only true ambiguity is between "E" and "T" sent all by
themselves. Unless
you know the speed from some other source, there's no way to tell
them apart.

Something easy for the brain but hard for
computers to do when the sender varies his speed.

Naw, just requires a bit more software.

73 de Jim, N2EY

What happened to your "1 and 0" and "mark and space" theory?