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proper cryptographic equipment. It also routes the decoded teletypewriter signal from the cryptographic
equipment to the selected tty.
CRYPTOGRAPHIC EQUIPMENT.—The cryptographic equipment converts the transmitted
coded signal to a decoded signal that can be printed out in its original state.
TELETYPEWRITER.—The tty equipment is used to convert the dc signal received from the
communication patch panel to a printed copy of the original transmitted message. The tty shown is used
only for receive and does not have the ability to transmit.
Q27. What are the functions of a converter-comparator group?
Afts System
Figure 3-27 is a simplified block diagram of a HALF-DUPLEX (send or receive) uhf, audio-
frequency-tone shift system. A half-duplex communications circuit permits two-way communications
between stations. Communications can be in either direction but not simultaneously. The term half-duplex
is qualified by adding send only, receive only, or send or receive. Let's use the block diagram to trace a
signal through the system.
Figure 3-27.—Half-duplex afts teletypewriter system.
SIGNAL FLOW.—On the transmit side, dc signals from the tty set are fed to the communication
patching panel. From the panel they are patched to the tone terminal set. The tone terminal set converts
