milliseconds for the stop pulse. Thus it takes 6 x 22 plus 31 or 163 milliseconds to transmit one letter or one figure. An
average word is 5 characters (letters), with a space after each word, making a total of 6 characters or 6 operations.
Therefore, it takes 6 x 163 or 978 milliseconds (.978 second) to transmit an average word. The rate of transmission is 60
seconds divided by .978 second per word which equals 61.3 WPM. This rate is generally rounded off and referred to as
60 WPM.
b. Baud. Instead of using the term words per minute to express the rate of a teletypewriter system, a different
term, the baud, is used internationally.
(1) The term baud expresses the rate of sending the shortest pulse in a character. One baud is a speed on 1 pulse
per second. Twenty baud is a speed of 20 pulses per second.
(2) To determine the baud number, divide 1 second by the time duration of one intelligence pulse. For example,
60 WPM equipment transmits at a rate of 1 second divided by 0.022 second of 45.5 baud.
(3) Standard teletypewriter equipment that operates at 45.5 baud (60 WPM) can be modified to operate at either
61.0 baud (75 WPM) or 74.2 baud (100 WPM). To do this, certain gears within the teletypewriter must be changed. As a
result, the pulse length or duration is shortened and the baud number is increased.
c. Bits per second. The term bits per second is sometimes used to describe the rate. A bit is equivalent to a
pulse. If all pulses including the start and stop pulses last for the same length of time, the bit rate is exactly the same as
the baud number. The term bit is used in data communication.
d. Operations per minute. Operations per minute (which is the same as the number of characters per minute) is
another term used to designate the rate of teletypewriter equipment. 61.3 WPM is equivalent to 61.3 WPM x 6 characters
per word or 368 operations per minute.
e. Dot frequency. There's still another term that's used--the dot frequency. A dot cycle is defined as the time
duration of a mark plus a space. Since a mark and a space take 44 milliseconds (22 x 2), the dot frequency is 1 second
divided by 0.044 second or 22.75 Hz. Note that the dot frequency is one half the baud number (b above).
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