78.
The Teletypewriter Code.
a. In
teletypewriter
communication the operator of the
sending teletypewriter types the
message on a special keyboard
and the machine transmits coded
combinations of current pulses
(called mark and space pulses) for
each character.
The coded
combinations of pulses is called
the Baudot Code. It is also known
as the 7.42-unit code and the Bell
code.
b. The Baudot code is a
five-unit, start-stop code. Each
character (letter, number, etc.) is a
combination of five intelligent
pulses (marks and spaces), plus a
start pulse and a stop pulse as
shown in figure 76. The start and
stop pulses start and stop the
receiving
teletypewriter
to
synchronize its operation with the
sending teletypewriter. The start
pulse is always a space and the
stop pulse is always a mark.
FIGURE 76. Baudot Code.
c. The start, intelligence, and stop pulses for the letter A are shown in A of figure 77. The series of pulses or
pulse train that represent the word "ARMY" in shown in B of figure 77.
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