You may find that your initial frequency assignments prove to be
unsatisfactory, thus requiring adjustments.
You may need to change
your original plans when frequencies used by the enemy, friendly
governments,
or
commercial
agencies
cause
interference
in
communication systems.
Harmonic frequencies of these sources, as
well as those of our own transmitters, may cause interference.
Harmonics are frequencies that are multiples of the assigned or
fundamental frequency.
For example, an assigned frequency of 4,000
KC may radiate interfering harmonic signals at 8,000 KC, 12,000 KC,
16,000 KC, and so forth.
These multiples of the fundamental
frequency are known respectively as the second, third, and fourth
harmonics.
There may also be times when it is impossible to provide radio
frequencies that permit all radio nets of a division to operate free
from interference. In such cases, you must silence a portion of the
nets, giving preference to nets and stations with the highest
CALL SIGNS
Call signs are used primarily for establishing and maintaining
They consist of any combination of characters or
pronounceable words that identify a communication facility, a
command, an authority, or a unit.
Periodic changing of call signs
provides communication security for a brief period, depending on the
amount of use and the quality of the enemy's traffic analysis. Call
signs that consist of four characters, such as 6B69 or DN8Z, are
authorized
for
radio-telegraph
(continuous
waves)
and
manual
teletypewriter (including radio teletypewriter), and are used for
voice operation on AM equipment.
Voice call signs that consist of
pronounceable words, such as BUTTER DIESEL or ACHING BUNKER, are
authorized for radio-telephone operators.
There are times when a headquarters is given a single call sign to
use in the different nets in which the headquarters is required to
operate. When a single call sign is used for both continuous waves
and radio-telephone nets, an assigned call sign such as XY24 is
acceptable for radio-telephone use by pronouncing the letters
phonetically: X-RAY YANKEE TOO FOWER.
When additional security is
required, you must ensure a different call sign is used for each net
in which the station is to operate.
When the attention of all stations in a radio net is desired, use the
net call sign. The use of this call sign facilitates net operation
and is often used by the net control station (NCS)
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TR1009
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