رد: إسرائيل توقف تطوير الميركافا 5 .


Laser deceptive jamming is designed to deceive and puzzle
enemy laser rangefinders and laser-guided weaponry using their
own laser jammers. Two approaches can be applied in realizing
deceptive jamming of laser rangefinders. One approach is as
follows: when irradiated by an enemy laser rangefinder signal,
transmitting (or reflecting), in a very short delay time, a
signal with the same wavelength and pulse width is generated
along the original path so that the enemy will mistake one target
with two targets. In this case, normally the enemy will manually
shift the gear for a new measurement, which will certainly lead
to missing the combat opportunity. The other jamming approach is
re-transmitting the enemy's ranging pulse after a delay period so
as to enlarge the error in the enemy rangefinding operations.
Germany developed a laser jammer in which numerous
converging lenses are placed around the defense platform; the
lenses are coupled with an optical-fiber delay line, while the
other end of the fiber is connected to a reflector. Thus, when
enemy laser rangefinding pulses are received, the laser signal
will be reflected back along the original path through optical
fiber delay line so that the enemy will receive a wrong ranging
signal. This equipment, not requiring a laser transmitter,
features simple structure and cost-effectiveness.
The expected effect, of deceptive jamming of laser-guided
weaponry is to deceive or puzzle the laser-guided weaponry by
creating a false target so as to conceal the real target. Based
on different jamming-generating techniques, active laser
deceptive jamming can be classified as retransmission jamming and
response jamming.
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Retransmission jamming: automatically amplifying the laser
pulse signal received by the laser alarming device and
retransmitting it from a laser jammer so as to generate a laser
deceptive jamming signal.
Response jamming: storing and accurately duplicating the
received laser pulse signal to create a laser deceptive jamming
signal.
To realize retransmission jamming, the jamming laser is
required not only to have high pulse repetition frequency, but
also must allow an extremely short transmission beam delay so
that the laser jamming signal can fall into the time gate of the
laser guidance system. In contrast, in response jamming, the
laser is required to have a high pulse repetition frequency, wide
range of pulse parameter variation, and high stability of leading
parameters. An actual active laser deceptive jamming system
always integrates retransmission jamming and response jamming.
Technically, a laser deceptive jamming system consists of a
laser alarm subsystem, active jamming subsystem, laser jamming
transmitter, and diffuse reflecting false target, etc. The major
function of the laser alarm subsystem is to detect the laser
threat signal and its arrival azimuth, and estimate the working
wavelength of the laser device, while the active jamming
subsystem is composed of signal sorter, pulse repetition
frequency measurement meter, code identification processor, and
synchronous retransmitter; it can be designed with a mixing mode
of microcomputer and integrating circuit.
When the laser alarm subsystem receives a pulse signal, the
signal sorter first executes azimuth sorting from different
azimuths of multiple laser threat sources, and then performs
pulse repetition frequency sorting for the multiple threat
sources with the same azimuth by using time correlation among
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coding pulses with the same series. The sorted single target
pulse signals should be subject to high-precision pulse
repetition frequency measurement to identify coding mode before
being retransmitted synchronously.
The laser jamming signal transmitted from the laser jammer
should be in total consistence with the laser guidance signal in
working wavelength, pulse width, and coding mode. An optically
false target is a diffuse reflecting body, whose major function
is to radiate the beam energy received from the laser jammer into
the hemispheric space, and introduce an angle deceptive signal in
the guidance head angle tracking system.
The key techniques in achieving active laser deceptive
jamming include:
• advanced laser alarming technique with high sensitivity,
low false-alarm rate, wide range of detection wavelength, and
wide dynamic range;
• multiple laser-threat-source signal-sorting technique;
• high precision pulse repetition frequency measurement
technique;
• code (3-bit code, 4-bit code, 5-bit code, 6-bit code and
pseudo-random code) identification technique;
• delay offset and synchronous retransmission technique;
• high performance laser technique with high output energy,
high repetition frequency, short transmission beam delay, wide
range of pulse parameter variation and high stability of major
parameters.
Through modularization, the U.S. Army AN/GLQ-13 vehicleborne
laser countermeasures system can protect crucial ground
targets with different shape and size from being attacked, and
can operate independently through self-testing equipment.
Analysis indicates that this system is designed with techniques
including laser reconnaissance alarm, active laser jamming and
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