e. Frequency
management,
a
responsibility
of
the
electronics (C-E) officer, looks to both the friendly and enemy use of the
The C-E officer coordinates frequency allocation,
assignment and use, and oversees the reporting and processing of all MIJI
incidents. In this way, frequency management is tied to the whole EP system.
f. Hostile EW activities reduce the effectiveness of U.S. Army systems
which require radiated electromagnetic energy for their operational use.
EP
devices and techniques are applied to reduce the vulnerability of these systems
to EW, limit the effect of EW on the operational capabilities of these systems,
and permit their continued use in the presence of EW.
EP are the
responsibility of every soldier who uses or supervises the use of electronic
equipment.
g. Fortunately, there are many preventive and remedial measures we can
take to help counter hostile EW.
Preventive measures include short
transmissions, correct radio procedures, and net discipline. These preventive
measures reduce your electronic signature.
h. Remedial measures are used once you suspect you have become the victim
of enemy EW. Be sure that the interference is in fact jamming and not a form
of mutual interference. A simple test such as disconnecting the antenna aids
in resolving whether the problem is internal or external, that is, if the noise
stops, it is external, if it continues, it is a good indication it could be the
radio itself.
i. To conduct ES or EA, the planner must know the frequency of the target
to ensure that it is within the capability of our EW systems. EW planners must
ensure that there is compatibility in modulation. Our tactical radios operate
using one or two common forms of modulation - amplitude modulated (AM) as with
our radio teletypewriter (RATT) or frequency modulated (FM) as used in our very
high frequency (VHF) single-channel radios, like the VRC-12 series radio. Both
AM and FM transmitters produce representative fraction (RF) carriers.
The
carrier is a wave of constant amplitude, frequency, and phase which can be
modulated by changing its amplitude, frequency, or phase. Thus, the RF carrier
"carries" intelligence by being modulated.
Modulation is the process of
superimposing intelligence (voice or coded signals) on the carrier.
In
frequency modulated signals, the amplitude of the signal remains constant but
the frequency changes.
On amplitude modulated communication signals, the
frequency of the wave stays the same but the amplitude changes. When operating
in an EW environment, FM is preferred. (See Figure 1-6, AM vs FM modulation.)
j. Consider the propagation paths that radio energy can follow. The basic
rule of thumb is that the higher the frequency, the shorter the radio waves and
the more direct the signal becomes. For planning EW operations, the radio path
a given radio signal is likely to follow, must be known.
k. The majority of U.S. and enemy communications in the tactical arena use
has inherent operational security weaknesses.
The radiation pattern is
omnidirectional in that the signal is transmitted 360 degrees.
i. The signal follows a direct-wave propagation path. Within this type of
environment, an enemy EW system that is capable of intercepting the direct wave
can exploit the signal by monitoring or locating it for targeting by physical
destruction or jamming.
Successful EW is contingent upon relative distance,
equipment, user, and enemy similarities in frequency bands and modulation.
IS3007
1-12
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