Military Communications and Information Technology: A Trusted ...

72 Military Communications and Information Technology...
and problems in ensuring effective work of radio-frequency (RF) jammer. Moreover
description of designed RCIED jamming system conception was presented.
II. IED technology
An IED is a homemade bomb, constructed and deployed in improvised manner
incorporating destructive, lethal, noxious, pyrotechnic or incendiary chemicals
and designed to destroy or incapacitate personnel or vehicles. In principle, any
explosive weapon not originated from an industrial production line may be classified
as an IED [1][5].
Historically, there is nothing new about IEDs which have been used in terrorist
actions for a long time or in unconventional warfare by guerrillas during World
War II. Recently wide use of IEDs is a main threat for Coalition Forces in Afghanistan.
IEDs are extremely diverse in design, and may contain many types of initiators,
detonators, penetrators, and explosive loads. This kind of devices is very effective
as they are made of elements that are easily available at low cost. Generally IED
consists of five components: a switch/trigger (activator), an initiator (fuse), container
(body), charge (explosive filler), and a power source (battery) if applicable. IEDs
can be produced in different sizes, functioning methods, containers, and delivery
methods. IEDs can utilize commercial or military explosives, homemade explosives,
or ordnance components. IEDs are triggered by various methods, including
radio remote control, infra-red or magnetic triggers, pressure-sensitive bars or trip
wires [3]. However, now there is a shift to more sophisticated detonation devices,
such as high-powered cordless phones or GSM handsets.
IEDs can be divided into three main categories, depending on the explosion
initiation:
• Victim Operated Devices – triggered by victims movement or pressure;
• Timed – triggered with the use of different kinds of timers;
• Command Operated – triggered by pulling out a safety pin using gossamerlike
wires/ropes, by generating an electric pulse over command wire or by
sending a trigger command over radio transmitter.
RCIED are classified to the Command Operated group, where the trigger
command is send by a radio transmitter to a hidden bomb attached to a receiver
linked to an electrical firing circuit. For this purpose, as radio transmitter can be
used a broad range of equipment from household gadget like a key fob car alarm
switch, remote controlled toys or a wireless doorbell buzzer to more sophisticated
pagers, CBs, cellular phones, modified HF/VHF/UHF transceivers and satellite
phones. Frequency range used by these devices is very diverse. RCIED triggers use
mainly commercial frequency bands listed in [1].
The simplest method that can prevent the activation of RCIED is disrupting RC
triggers by blocking the radio signal. For this purpose jamming techniques are
used. Effective jamming of the whole frequency range used by RCIED is practically