b. Net Control Station. The net control station opens the net and controls
transmissions within the net, including entering the net (requesting permission to
transmit) and leaving the net (signing off).
c. Call Sign. Each station within a radio net has an individual call sign that
identifies the station to other members of the net. A call sign consists of a letter-
number-letter combination and is usually followed by a suffix, such as A2D-28.
Sometimes an abbreviated call sign consisting of the last letter of the call sign and the
suffix is used, such as D-28.
d. Authentication. Authentication systems are used as a security precaution to
determine if the receiving or transmitting station is actually a friendly station. The
challenging party transmits a code to which the challenged party must give a proper
reply. Authentication is performed in accordance with communications-electronics
operation instructions (CEOI) procedures.
e. COMMUNICATIONS-ELECTRONICS OPERATION INSTRUCTIONS.
Communications-electronics operation instructions are a series of orders issued for the
technical control and coordination of the signal communications of a command.
f. COMMUNICATIONS-ELECTRONICS STANDING INSTRUCTION.
Communications-electronics standing instruction is a series of instructions explaining
the use of items included in the CEOI plus any other technical instructions required to
coordinate and control the communications-electronics operations of the command.
g. DRYAD. DRYAD is the unclassified term used to describe the numerical
cipher/authentication system.
h. Cipher System. A cipher system is any crypto system that, by means of a
key, converts plain text into an unintelligible form and converts encrypted text back to
plain text.
i. In the Clear. Information transmitted in the clear is transmitted as plain text,
not encoded or encrypted.
j. AUTOMATED NET CONTROL DEVICE. Automated net control device
(ANCD).
5-18. GENERAL RULES
The following are some general rules for communicating over a radio.
a. Preplan messages. Know what you are going to say before you begin to
speak into the microphone.
b. Listen before you transmit to make sure no conversation is already in
progress on the net.
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