Graphics Programs Reference
In-Depth Information
Denial ECM techniques: Denial ECM techniques can be either active or
passive. Active denial ECM techniques include: CW, short pulse, long
pulse, spot noise, barrage noise, and sidelobe repeaters. Passive ECM tech-
niques include chaff and Radar Absorbing Material (RAM).
1.
Deception ECM techniques: Deception ECM techniques are also broken
down into active and passive techniques. Active deception ECM techniques
include repeater jammers and false target generators. Passive deception
ECM include chaff and RAM.
2.
10.2. Jammers
Jammers can be categorized into two general types: (1) barrage jammers and
(2) deceptive jammers (repeaters). When strong jamming is present, detection
capability is determined by receiver signal-to-noise plus interference ratio
rather than SNR. In fact, in most cases, detection is established based on the
signal-to-interference ratio alone.
Barrage jammers attempt to increase the noise level across the entire radar
operating bandwidth. Consequently, this lowers the receiver SNR, and, in turn,
makes it difficult to detect the desired targets. This is the reason why barrage
jammers are often called maskers (since they mask the target returns). Barrage
jammers can be deployed in the main beam or in the sidelobes of the radar
antenna. If a barrage jammer is located in the radar main beam, it can take
advantage of the antenna maximum gain to amplify the broadcasted noise sig-
nal. Alternatively, sidelobe barrage jammers must either use more power, or
operate at a much shorter range than main beam jammers. Main beam barrage
jammers can be deployed either on-board the attacking vehicle, or act as an
escort to the target. Sidelobe jammers are often deployed to interfere with a
specific radar, and since they do not stay close to the target, they have a wide
variety of stand-off deployment options.
Repeater jammers carry receiving devices on board in order to analyze the
radarÓs transmission, and then send back false target-like signals in order to
confuse the radar. There are two common types of repeater jammers: spot noise
repeaters and deceptive repeaters. The spot noise repeater measures the trans-
mitted radar signal bandwidth and then jams only a specific range of frequen-
cies. The deceptive repeater sends back altered signals that make the target
appear in some false position (ghosts). These ghosts may appear at different
ranges or angles than the actual target. Furthermore, there may be several
ghosts created by a single jammer. By not having to jam the entire radar band-
width, repeater jammers are able to make more efficient use of their jamming
power. Radar frequency agility may be the only way possible to defeat spot
noise repeaters.
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