locked-on frequency ceases.
An intercept receiver and jamming transmitter
system which searches for, and automatically jams, signals which have specific
radiation characteristics is sometimes referred to as an automatic search
jammer or a search-lock jammer.
(2) Reradiation Jamming.
Jamming by reradiation is accomplished by receiver-transmitter
assemblies.
When used in a jamming role, repeaters and transponders are
essentially
automated jammers.
Repeaters. Repeaters intercept the enemy's signal, alter it in some
fashion, amplify the altered version, and retransmit it for the purpose of
disrupting or falsifying the information transmitted to the enemy's receiver.
Repeater applications for jamming and deception are generally limited only by
the state of the electronic technology and the ingenuity of the individual in
devising methods for altering the intercepted signal. Delaying retransmission
of the intercepted signal will produce an unintelligible output from many
electronic systems receiving both the original and altered versions of the
signal at the same time.
Transponders.
Transponders automatically transmit a predetermined
signal and are programmed to respond to specific types of victim signals.
(3) Reflection Jamming.
Reflection jamming is normally used to confuse enemy radar. Reflective devices
such as chaff, rope, and corner reflectors provide enemy electronic systems
with false targets or hide actual targets, and thereby degrade their effective
operation.
Chaff. Chaff consists of narrow metallic strips of various lengths and
frequency responses, and is used to reflect echoes to the receiving components
of the radars. Chaff reflects a signal which appears on a radar scope as a
series of spaced echoes or as one continuously lengthening target indication.
The expansion of echoes on a radar display is because of dispersion of the
chaff after launching.
Rope. Rope is a form of chaff consisting of a long roll of metallic
foil or wire, designed for a broad, low-frequency response. The echo reflected
by rope appears on a radar scope as a single target or a formation of targets.
Corner Reflectors.
Corner reflectors consist of flat reflecting
surfaces connected to form a three-dimensional reflector. The reflector may be
produced in a variety of shapes, including cubes, diamonds, and pyramids.
Because of its electromagnetic reflective efficiency, the corner reflector
appears on a radar as a much larger target.
When rotated, the reflector
appears as a moving target.
e. Jamming range is affected by the terrain, vegetation and weather,
distance to the enemy receiver, radio line of sight (LOS) to the enemy
receiver, and other technical factors.
The distance between the enemy
transmitter and receiver affects jamming.
In jamming you must disrupt or
degrade the signal received by the enemy receiver.
1-9
IS3007
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