288:
613:(ARM) also known as Home-On-Jam (HOJ) missiles: When a target is using self-protective jamming (SPJ), it essentially broadcasts its position. An ARM could be deployed and take out the jamming source. The missile utilizes passive RF homing which reduces its probability of detection. A countermeasure to ARM is not to use self-protective jamming (one could use stand-off jamming, assuming that the missiles has a range no longer than the radar), or have a decoy taking the missile (such as
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662:, being picked up by its radar. This interference is eliminated by suppressing the radar's reception for the duration of the transponder's transmission. Instead of "bright-light" rabbits across the display, one would observe very small black dots. Because the external radar causing the transponder to respond is generally not synchronised with your own radar (i.e. different
666:), these black dots appear randomly across the display and the operator sees through and around them. The returning image may be much larger than the "dot" or "hole", as it has become known, anyway. Keeping the transponder's pulse widths very narrow and mode of operation (single pulse rather than multi-pulse) becomes a crucial factor.
96:
is made of different length metallic strips, which reflect different frequencies, to create a large area of false returns in which a real contact would be difficult to detect. Modern chaff is usually aluminum-coated glass fibers of various lengths. Their extremely low weight and small size allow them
208:
in the early 1950s, and was so effective it was believed that all long-range radar systems might be rendered useless. However, the jamming effect can be limited because this requires the jammer to spread its full power between these frequencies—the effectiveness against each frequency decreases with
651:
scope with useless data. Interference is not that common between ground radars, however, because they are not usually placed close enough together. It is more likely that some sort of airborne radar system is inadvertently causing the interference—especially when two or more countries are involved.
526:
In some cases, jamming of either type may be caused by friendly sources. Inadvertent mechanical jamming is fairly common because it is indiscriminate and affects any nearby radars, hostile or not. Electronic jamming can also be inadvertently caused by friendly sources, usually powerful EW platforms
646:
While not usually caused by the enemy, interference can greatly impede the ability of an operator to track. Interference occurs when two radars in relatively close proximity (how close they need to be depends on the power of the radars) are operating on the same frequency. This will cause "running
248:
technique that manipulates received radar energy and retransmits it to change the return the radar sees. This technique can change the range the radar detects by changing the delay in transmission of pulses, the velocity the radar detects by changing the
Doppler shift of the transmitted signal, or
669:
The external radar could, in theory, come from an aircraft flying alongside your own, or from space. Another factor often overlooked is to reduce the sensitivity of one's own transponder to external radars; i.e., ensure that the transponder's threshold is high. In this way it will only respond to
122:
are maneuverable flying objects that are intended to deceive a radar operator into believing that they are actually aircraft. They are especially dangerous because they can clutter up a radar with false targets making it easier for an attacker to get within weapons range and neutralize the radar.
63:
There are two general classes of radar jamming, mechanical and electronic. Mechanical jamming entails reflecting enemy radio signals in various ways to provide false or misleading target signals to the radar operator. Electronic jamming works by transmitting additional radio signals towards enemy
253:
techniques to transmit into the sidelobes of the radar. Electronics, radio equipment, and antenna can cause DRFM jamming causing false targets, the signal must be timed after the received radar signal. By analysing received signal strength from side and backlobes and thus getting radar antennae
191:
is a modification of spot jamming where the jammer's full power is shifted from one frequency to another. While this has the advantage of being able to jam multiple frequencies in quick succession, it does not affect them all at the same time, and thus limits the effectiveness of this type of
127:
can be fitted on decoys to make them appear larger than they are, thus furthering the illusion that a decoy is an actual aircraft. Some decoys have the capability to perform electronic jamming or drop chaff. Decoys also have a deliberately sacrificial purpose i.e. defenders may fire
490:
101:. Ships, on the other hand, can benefit greatly from a slow-moving chaff cloud. The cloud is released within the resolution cell of the ship and moves with the wind in one direction. The ship then escapes in another direction. The decoy (chaff cloud) should have a larger
160:
where jammers radiate interfering signals toward an enemy's radar, blocking the receiver with highly concentrated energy signals. The two main technique styles are noise techniques and repeater techniques. The three types of noise jamming are spot, sweep, and barrage.
509:
The burn-through range is the distance from the radar at which the jamming is ineffective. When a target is within this range, the radar receives an adequate target skin return to track it. The burn through range is a function of the target RCS
567:
Limiting unsecure radio communication concerning the jamming and its effectiveness is also important. The jammer could be listening, and if they know that a certain technique is effective, they could direct more jamming assets to employ this
254:
radiation pattern, false targets can be created to directions other than one where the jammer is coming from. If each radar pulse is uniquely coded it is not possible to create targets in directions other than the direction of the jammer.
571:
The most important method to counter radar jammers is operator training. Any system can be fooled with a jamming signal but a properly trained operator pays attention to the raw video signal and can detect abnormal patterns on the radar
172:
occurs when a jammer focuses all of its power on a single frequency. This overwhelms the reflection of the original radar signal off the targets, the "skin return" or "skin reflection", making it impossible to pick out the target on the
97:
to form a dense, long-lasting cloud of interference. This cloud is only effective in the range cell that it occupies. The slow movement of the chaff (compared to a flying target) makes it easily discriminated, based on the lacking
181:(PRF) so the jammer is no longer broadcasting on the same frequency or at the right times. While multiple jammers could possibly jam a range of frequencies, this would consume many resources and be of little effect against modern
113:
have the same effect as chaff but are physically very different. Corner reflectors are many-sided objects that re-radiate radar energy mostly back toward its source. An aircraft cannot carry as many corner reflectors as it can
560:
will limit the effectiveness of most jamming, making it easier to read through it. Modern jammers can track a predictable frequency change, so the more random the frequency change, the more likely it is to counter the
318:
575:
The best indicator of jamming effectiveness to the jammer is countermeasures taken by the operator. The jammer does not know if their jamming is effective before operator starts changing radar transmission
225:
produces noise pulses with period depending on radar mast rotation speed thus creating blocked sectors from directions other than the jammer, making it harder to discover the jammer location.
701:
species has been confirmed. This can be seen as nature's equivalent of radar jamming. Similar to human ECCM techniques, bats are found to change their emission lengths to defeat jamming.
579:
Using EW countermeasures will give away radar capabilities thus on peacetime operations most military radars are used on fixed frequencies, at minimal power levels and with blocked
177:. This technique is only useful against radars that broadcast on a single frequency, and can be countered by changing the frequency or other operational parameters like the
219:
is a new type of barrage jamming whereby one radar is jammed effectively at its source at all frequencies. However, all other radars continue working normally.
87:
energy back to the radar to produce false target returns on the operator's scope. Mechanical jamming devices include chaff, corner reflectors, and decoys.
634:
of the protected aircraft will improve the jamming efficiency (higher J/S). A lower RCS also reduces the "burn-through" range. Stealth technologies like
200:
is a further modification of sweep jamming in which the jammer changes frequencies so rapidly it appears to be a constant radiator across its entire
204:. The advantage is that multiple frequencies can be jammed essentially simultaneously. The first effective barrage jammer was introduced as the
841:
564:
Cloaking the outgoing signal with random noise makes it more difficult for a jammer to figure out the frequency that a radar is operating on.
621:). By towing a decoy/jammer, the decoy maintains a realistic Doppler shift (which tricks the tracker) and lures an ARM away from the target.
485:{\displaystyle {\frac {J}{S}}={\frac {EIRP_{jam}}{EIRP_{radar}}}\times {\frac {4\pi R^{2}}{\sigma }}\times {\frac {BW_{radar}}{BW_{jam}}}}
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719:
593:
830:
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creates a short noise pulse when radar signal is received thus concealing any aircraft flying behind the jammer with a block of noise.
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The interference between airborne radars referred to above can sometimes (usually) be eliminated by frequency-shifting transmitters.
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725:
618:
580:
72:
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at the decoys, thereby depleting limited stocks of expensive weaponry which might otherwise have been used against genuine targets.
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jamming. Although, depending on the error checking in the device this can render a wide range of devices effectively useless.
64:
receivers, making it difficult to detect real target signals, or take advantage of known behaviors of automated systems like
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597:
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or false information. Concepts that blanket the radar with signals so its display cannot be read are normally known as
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178:
989:
710:
299:
34:
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515:
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is more simple than military-grade radar jamming. The laws about jamming police radars vary by jurisdiction.
819:
758:
926:"High duty cycle moth sounds jam bat echolocation: bats counter with compensatory changes in buzz duration"
610:
92:
882:
737:
694:
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The other interference often experienced is between the aircraft's own electronic transmitters, i.e.
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607:
system would automatically detect attempts at deceptive jamming, which might otherwise go unnoticed.
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deliberately makes some returns look larger on radar in order to hide their nature. This is used by
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511:
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102:
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the number of frequencies covered. The creation of extremely powerful multi-frequency radars like
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are usually kept passive when military operations are not ongoing to keep radar locations secret.
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Corcoran, A. J.; Barber, J. R.; Conner, W. E. (16 July 2009). "Tiger Moth Jams Bat Sonar".
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149:
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75:(ECCMs) can sometimes help radar operators maintain target detection despite jamming.
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49:
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56:, while systems that produce confusing or contradictory signals are known as
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41:
17:
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One should also reduce the power output of the transponder in like manner.
60:, but it is also common for all such systems to be referred to as jamming.
808:
776:
761: – Device designed to protect aircraft from infrared homing missiles
245:
941:
767: – Radar technology that hides its activity from a detected target
518:), the radars ERP and required J/S (for the jamming to be effective).
820:
EW 101: a first course in electronic warfare By David Adamy, page 196
83:
Mechanical jamming is caused by devices that reflect or re-reflect
842:"Quantum Imaging Technique Heralds Unjammable Aircraft Detection."
542:
534:
118:
84:
45:
38:
552:
Constantly alternating the frequency that the radar operates on (
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rabbits", a visual phenomenon that can severely clutter up a
785: – Interference with authorized wireless communications
600:(LPI) modes to reduce the chance that the radar is detected.
596:(AESA) radars are innately harder to jam and can operate in
924:
Fernández, Y; Dowdy, NJ; Conner, WE (15 September 2022).
746: – Electronic device for deceiving detection systems
755: – Combat involving electronics and directed energy
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Pages displaying short descriptions of redirect targets
321:
734: – Electronic warfare professional organization
715:
Pages displaying wikidata descriptions as a fallback
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nearby radars—which, after all, should be friendly.
583:
sectors toward possible listeners (country borders).
681:Jamming radar for the purpose of defeating police
484:
728: – Countermeasure from radar guided missiles
152:. This fighter specializes in electronic warfare.
150:Tornado ECR (Electronic Combat / Reconnaissance)
773: – Former Royal Air Force operations group
185:radars that constantly change their broadcasts.
740: – Interference with animal sonar systems
638:can be used to reduce the return of a target.
527:operating within range of the affected radar.
105:(RCS) than the target, so the radar tracks it.
539:Home-on-jam missile attacking an SPJ aircraft
8:
213:offset the effectiveness of the carcinotron.
779: – Russian ground-based jamming system
44:signals to interfere with the operation of
809:Radar Countermeasures: Range Gate Pull-Off
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831:ELECTRONIC WARFARE QUICK REFERENCE GUIDE
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7:
37:(ECMs) that intentionally sends out
930:The Journal of Experimental Biology
720:Active electronically scanned array
594:Active electronically scanned array
505:Radar range, and burn-through range
854:"What is a (Police) Radar Jammer?"
765:Low-probability-of-intercept radar
722: – Type of phased array radar
73:Electronic counter-countermeasures
27:Form of electronic countermeasures
25:
789:Suppression of Enemy Air Defenses
726:AN/ALE-55 Fiber-Optic Towed Decoy
619:AN/ALE-55 Fiber-Optic Towed Decoy
630:For protective jamming, a small
298:
286:
249:the angle to the plane by using
156:Electronic jamming is a form of
48:by saturating its receiver with
276:to make them look as large as
236:Digital radio frequency memory
1:
636:radiation-absorbent materials
664:pulse-repetition frequencies
598:low probability of intercept
293:Protective/Standoff jamming
31:Radar jamming and deception
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980:Electronic countermeasures
547:Home-on-jam countermeasure
179:pulse repetition frequency
35:electronic countermeasures
711:36th Bombardment Squadron
305:Protective/Escort jamming
732:Association of Old Crows
516:Effective radiated power
264:" to break a radar lock.
895:10.1126/science.1174096
791: – Military tactic
759:Infrared countermeasure
68:to confuse the system.
611:Anti-radiation missile
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540:
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486:
260:uses techniques like "
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713: – military unit
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538:
504:
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144:
738:Echolocation jamming
695:jamming of bat sonar
677:Jamming police radar
319:
887:2009Sci...325..325C
632:radar cross section
588:fire control radars
522:Inadvertent jamming
512:Radar cross-section
262:range gate pull-off
229:Cover pulse jamming
103:radar cross-section
942:10.1242/jeb.244187
753:Electronic warfare
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541:
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497:Radar burn-through
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158:electronic warfare
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137:Electronic jamming
79:Mechanical jamming
881:(5938): 325–327.
771:No. 100 Group RAF
744:Electronic attack
689:Jamming in nature
554:frequency agility
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397:
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258:Deceptive jamming
238:, or DRFM jamming
125:Corner reflectors
110:Corner reflectors
16:(Redirected from
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990:Penetration aids
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269:Blip enhancement
242:Repeater jamming
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197:Barrage jamming
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33:is a form of
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857:. Retrieved
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660:transponders
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642:Interference
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615:ADM-160 MALD
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274:escort ships
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217:Base jamming
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166:Spot jamming
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30:
29:
18:Radar jammer
697:by certain
211:Blue Riband
206:carcinotron
974:Categories
859:2013-03-14
796:References
699:tiger moth
683:radar guns
170:spot noise
911:206520028
576:settings.
556:) over a
428:×
423:σ
409:π
400:×
202:bandwidth
147:Luftwaffe
58:deception
42:frequency
960:36111562
903:19608920
777:Pelena-1
705:See also
246:repeater
71:Various
951:9637272
883:Bibcode
875:Science
626:Stealth
586:Mobile
572:screen.
568:method.
561:jammer.
145:German
54:jamming
958:
948:
936:(18).
909:
901:
119:Decoys
114:chaff.
995:Radar
907:S2CID
244:is a
240:, or
93:Chaff
85:radar
50:noise
46:radar
39:radio
956:PMID
899:PMID
693:The
617:and
946:PMC
938:doi
934:225
891:doi
879:325
168:or
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581:Tx
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417:2
413:R
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392:r
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376:P
372:R
369:I
366:E
359:m
356:a
353:j
349:P
345:R
342:I
339:E
333:=
328:S
325:J
280:.
20:)
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