[GreenKeys] BAUD -vs- WPM

[Jim Haynes]

On Fri, 9 May 2014, tony.podrasky wrote:
>
> 45.45 BAUD = 60  WPM
> 110.00 BAUD = 100 WPM
>
Well you would expect 100 wpm to finish faster than 60 wpm on the same
text.  Because it's faster words per minute.

However - now in binary BAUD=bits/second, so

45.45 bits/second divided by 7.42 bits/character gives 6.1-something
characters per second.  Which multiplied by 60 seconds/minute and divided
by 6 characters/word (counting the space between words) gives 61 
something words/minute.  The more official figure in terms of shaft speed
is 368 operations (characters)/minute or 61.3 words/minute.  But it is
slowed down by the stopping between character


110 bits/second divided by 11 bits/character gives 10 characters per
second, and that gives 100 words/minute.

These things get jiggled a little by the fact that gears have to have an
integral number of teeth.  You could take the motor speed of 1800 rpm
(model 15, sync motor) or 3600 rpm (Model 28, 35) and calculate the
shaft speeds from the gear ratios.  Noting that the receiving shaft has
to be faster than the incoming character so it has time to stop between
characters, and then the main shaft to keyboard gearing slows down the
keyboard.

Others (left as an exercise for the student) are Western Union 5-level
code uses 7.00 units instead of 7.42, but the same 45.45 baud, so you
get a faster wpm.  And European (which include Model 32) use 7.50 code
and 50 baud, so again you get a different wpm.