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45-584: This is an Iranian SACLOS beam-riding SHORAD surface-to-air missile . With a range of six kilometers and a maximum altitude of two kilometers, the Qaem is intended for use against UAVs and low flying or stationary helicopters. The Qaem is a development of the Toophan missile, itself an unlicensed copy of the American BGM-71 TOW missile, and entered mass production in 2010. The Qaem anti-aircraft missile uses

90-426: A busy frequency without first checking whether it is in use, or without being able to hear stations using the frequency. Another form of unintentional jamming occurs when equipment accidentally radiates a signal, such as a cable television plant that accidentally emits on an aircraft emergency frequency. Originally the terms were used interchangeably but nowadays most radio users use the term "jamming" to describe

135-512: A directional loop aerial that would enable them to hear the stations through the jamming. In the Netherlands such aerials were nicknamed "moffenzeef" (English: "kraut sieve"). During the Continuation War , after discovering the fact that the mines that the retreating Soviet forces had scattered throughout the city of Viipuri were radio-triggered rather than timer- or pressure-triggered,

180-541: A former subsidiary of the French state-owned company Thales Group . Debates have been raised in Iran regarding the possible health hazards of satellite jamming. Iranian officials including the health minister have claimed that jamming has no health risk for humans. However, the minister of communication has recently admitted that satellite jamming has 'serious effects' and has called for identification of jamming stations so they can put

225-593: A larger variant named Qaem-5 , with TV guidance; and an even larger variant named Qaem-9 , also with TV guidance. The Qaem A2G glide bomb is related to the Sadid-345 glide bomb, but has different wings and size. This article related to the Iranian armed forces is a stub . You can help Misplaced Pages by expanding it . This article relating to missiles is a stub . You can help Misplaced Pages by expanding it . SACLOS Semi-automatic command to line of sight ( SACLOS )

270-501: A laser guidance system. Iran also produces a variant, the Qaem-M , which adds a proximity fuse. North Korea may operate Qaem-114. A completely unrelated Iranian munition, but also named "Qaem," is carried by Qods Mohajer-6 UAVs and Hamaseh UAVs. The Qaem is available in four variants: the Qaem 1 , with a suspected infrared seeker; a variant simply named Qaem , with suspected laser guidance;

315-407: A loop of traditional Chinese music while it is jamming channels (cf. Attempted jamming of numbers stations ). The purpose of this type of jamming is to block reception of transmitted signals and to cause a nuisance to the receiving operator. One early Soviet attempt at jamming Western broadcasters used the noise from the diesel generator that was powering the jamming transmitter. Subtle jamming

360-603: A stop to this practice. The government has generally denied any involvement in jamming and claimed they are sent from unknown sources. According to some sources, IRGC is the organization behind satellite jamming in Iran. The Russian Armed Forces have, since the summer of 2015, begun using a multi-functional EW weapon system in Ukraine , known as Borisoglebsk 2 . It is postulated that this system has defeated communications in parts of that country, including mobile telephony and GPS systems. Radio jamming (or "comm jamming")

405-659: Is a common plot element in the Star Wars franchise. In Star Wars: Episode VI - Return of the Jedi , when the Rebel fleet approaches the Galactic Empire's force, believing themselves to be launching a surprise attack, General Lando Calrissian realizes the Empire is jamming their signals, and therefore know they are approaching. In the film Star Trek II , after receiving a distress call from

450-461: Is a method of missile command guidance . In SACLOS, the operator must continually point a sighting device at the target while the missile is in flight. Electronics in the sighting device and/or the missile then guide it to the target. Many SACLOS weapons are based on an infrared seeker aligned with the operator's gunsight or sighting telescope . The seeker tracks the missile, either the hot exhaust from its rocket motor or flares attached to

495-421: Is based on the beam riding principle. In this case, a signal is sent from the operator's sights toward the target. The signal is generally radio or a laser . The missile has receivers for the signal on the rear of the fuselage. Some form of encoding is used in the signal so that the missile can steer itself into the center of the beam. Changing frequencies or dot patterns are also commonly used. These systems have

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540-556: Is easy to detect because it can be heard on the receiving equipment. It is usually some type of noise, such as stepped tones (bagpipes), random-keyed code, pulses, music (often distorted), erratically warbling tones, highly distorted speech, random noise (hiss), and recorded sounds. Various combinations of these methods may be used, often accompanied by regular Morse identification signals to enable individual transmitters to be identified in order to assess their effectiveness. For example, China, which did and does use jamming extensively, plays

585-452: Is jamming during which no sound is heard on the receiving equipment. The radio does not receive incoming signals; yet everything seems superficially normal to the operator. These are often technical attacks on modern equipment, such as "squelch capture". Thanks to the FM capture effect , frequency modulated broadcasts may be jammed, unnoticed, by a simple unmodulated carrier. The receiver locks on to

630-641: Is usually aimed at radio signals to disrupt control of a battle. A transmitter , tuned to the same frequency as the opponents' receiving equipment and with the same type of modulation , can, with enough power, override any signal at the receiver . Digital wireless jamming for signals such as Bluetooth and WiFi is possible with very low power. The most common types of this form of signal jamming are random noise , random pulse, stepped tones, warbler, random keyed modulated CW , tone, rotary, pulse, spark, recorded sounds, gulls, and sweep-through. These can be divided into two groups: obvious and subtle. Obvious jamming

675-658: Is usually of limited effectiveness because the affected stations usually change frequencies, put on additional frequencies and/or increase transmission power. Jamming has also occasionally been used by the governments of Germany (during World War II ), Israel , Cuba, Iraq, Iran (during the Iran-Iraq War ), China, North and South Korea and several Latin American countries, as well as by Ireland against pirate radio stations such as Radio Nova . The United Kingdom government used two coordinated, separately located transmitters to jam

720-805: The Battle of the Beams Britain jammed navigation signals used by German aircraft while the Soviets attempted to do likewise to American aircraft during the Berlin Airlift Since the Soviet Union started jamming Western radio broadcasts to the Soviet Union in 1948 the primary targets have been the BBC External Broadcasting Services , Voice of America (VOA) and especially RFE/RL . Western nations had allowed jamming prior to World War II, but in

765-595: The Suez Crisis ), Greek (prior to Cyprus gaining independence) and Rhodesian stations. During the early years of the Northern Ireland troubles the British army regularly jammed broadcasts from both Republican and Loyalist paramilitary groups. In 2002, China acquired standard short-wave radio-broadcasting equipment designed for general public radio-broadcasting and technical support from Thales Broadcast Multimedia,

810-499: The anti-aircraft role, the target is typically already being illuminated by a radar signal. However, a beam-riding missile flies directly at the target, which is often inefficient for a high-speed target like an aircraft. For this reason, most anti-aircraft missiles follow their own route to intercept the target, and do not ride the beam. A more modern use of beam-riding uses laser signals because they are compact, less sensitive to distance, and are difficult to detect and jam. This

855-402: The deliberate use of radio noise or signals in an attempt to disrupt communications (or prevent listening to broadcasts) whereas the term "interference" is used to describe unintentional forms of disruption (which are far more common). However, the distinction is still not universally applied. For inadvertent disruptions, see electromagnetic compatibility . Intentional communications jamming

900-492: The offshore radio ship, Radio North Sea International off the coast of Britain in 1970. In occupied Europe the Nazis attempted to jam broadcasts to the continent from the BBC and other allied stations. Along with increasing transmitter power and adding extra frequencies, attempts were made to counteract the jamming by dropping leaflets over cities instructing listeners to construct

945-518: The signal-to-noise ratio . The concept can be used in wireless data networks to disrupt information flow. It is a common form of censorship in totalitarian countries, in order to prevent foreign radio stations in border areas from reaching the country. Jamming is usually distinguished from interference that can occur due to device malfunctions or other accidental circumstances. Devices that simply cause interference are regulated differently. Unintentional "jamming" occurs when an operator transmits on

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990-531: The Finnish forces played Vesterinen 's recording of Säkkijärven Polkka without any pauses from September 4, 1941 to February 2, 1942, as they, to demine the city, needed to block the Soviets from activating the mines through the correct radio wave. The Soviets tried to trigger the mines by changing frequency; the mines had been set up to be able to be triggered by three different frequencies. The Finns countered this by playing Säkkijärven Polkka on all frequencies. During

1035-451: The Soviet Union and Eastern Bloc devised ingenious methods (such as homemade directional loop antennas ) to hear the Western stations through the noise. Because radio propagation on shortwave can be difficult to predict reliably, listeners sometimes found that there were days/times when the jamming was particularly ineffective because radio fading (due to atmospheric conditions ) was affecting

1080-471: The Soviet Union itself Bulgaria was one of the most prolific operators of jamming transmitters in the Eastern bloc with East Germany and Yugoslavia the least. While western governments may have occasionally considered jamming broadcasts from Eastern Bloc stations, it was generally accepted that doing so would be a pointless exercise. Ownership of shortwave radios was less common in western countries than in

1125-628: The Soviet Union where, due to the vast physical size of the country, many domestic stations were relayed on shortwave as it was the only practical way to cover remote areas. Additionally, western governments were generally less afraid of intellectual competition from the Eastern Bloc. In Francoist Spain the dictatorship jammed for decades Radio España Independiente , the radio station of the Communist Party of Spain which broadcast from Moscow (1941–1955), Bucharest (1955–1977) and East Berlin. It

1170-458: The advantage that the link between the launcher and missile cannot easily be broken or jammed. But, they have a disadvantage because the guidance signal may be detected by the target. Examples include the laser-guided RBS 70 SAM and 9M120 Svir ATGM. With wire- and radio-guided SACLOS, the sighting device can calculate the angular difference in direction from the missile position to the target location. It can then give electronic instructions to

1215-493: The already heavily overcrowded shortwave bands to such an extent that many broadcasters not directly targeted by the jammers (including pro-Soviet stations) suffered from the rising levels of noise and interference. There were also periods when China and the Soviet Union jammed each other's programmes. The Soviet Union also jammed Albanian programmes at times. Some parts of the world were more impacted by these broadcasting practices than others Meanwhile, some listeners in

1260-546: The center of the field of view, and the electronics automatically apply a correction instruction in the opposite direction of the change to re-center the missile. These instructions are delivered either by a radio link or a wire. Radio links have the disadvantage of being jammable , whereas wire links have the disadvantages of being limited to the length of the wire and fragile (i.e. not very good for penetrating/attacking targets in vegetated areas such as forests) and can not be fired over bodies of water due to potential shorting of

1305-509: The channel is free. Simple continuous transmission on a given channel will continuously stop a transmitter transmitting, hence jamming the receiver from ever hearing from its intended transmitter. Other jammers work by analysing the packet headers and, depending on the source or destination, selectively transmitting over the end of the message, corrupting the packet. During World War II , ground radio operators would attempt to mislead pilots by false instructions in their own language , in what

1350-420: The jamming signals but favouring the broadcasts (a phenomenon sometimes dubbed "twilight immunity"). On other days of course the reverse was the case. There were also times when jamming transmitters were (temporarily) off air due to breakdowns or maintenance. The Soviets (and most of their Eastern bloc allies) used two types of jamming transmitter. Skywave jamming covered a large area but for the reasons described

1395-537: The jamming station in order that Soviet monitoring posts could assess the effectiveness of each station. In 1987 after decades of generally refusing to acknowledge that such jamming was even taking place the Soviets finally stopped jamming western broadcasts with the exception of RFE/RL which continued to be jammed for several months into 1988. Previously there had been periods when some individual Eastern bloc countries refrained from jamming Western broadcasts but this varied widely by time and country. In general outside of

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1440-443: The larger carrier signal, and hence will ignore the FM signal that carries the information. Digital signals use complex modulation techniques, such as QPSK . These signals are very robust in the presence of interfering signals. But the signal relies on hand shaking between the transmitter and receiver to identify and determine security settings and method of high-level transmission. If the jamming device sends initiation data packets,

1485-566: The missile airframe, and measures the angle between the missile and the centerline of the operator's sights. This signal is sent to the missile, often using thin metal wires or a radio link , which causes it to steer back toward the center of the line-of-sight. Common examples of these weapons include the BGM-71 TOW wire-guided anti-tank guided missile (ATGM) and the Rapier radio-command surface-to-air missile (SAM). Another class of SACLOS weapons

1530-409: The missile near the center of the gunners line of sight immediately after launch, and a narrow view lens with automatic zoom that accomplishes the fine tracking adjustments. In most configurations, the narrow field camera utilizes electronics that translate the brightest spot in the view – the flare or strobe of the missile – into an electrical impulse. This impulse changes as the missile leaves

1575-481: The missile that correct its flight path so it is flying along a straight line from the sighting device to the target. Most antitank SACLOS systems such as Milan and TOW use a strobe or flare ( visible , infrared (IR) or ultraviolet (UV) light) in the tail of the missile with an appropriate sensor on the firing post, to track the missile's flight path. The launching station incorporates a tracking camera with two lenses. A wide field of view lens that locates and "gathers"

1620-427: The opposite of manual command to line of sight (MCLOS) ones, thus allowing updated version of such anti-tank weapons (notably AT-3 Malyutka ) to still remain in service in some countries. Radio jamming Radio jamming is the deliberate blocking of or interference with wireless communications . In some cases, jammers work by the transmission of radio signals that disrupt telecommunications by decreasing

1665-694: The post-War era the Western view has been that jamming violates the freedom of information while the Soviet view has been that under the international law principle of national sovereignty jamming is an acceptable response to foreign radio broadcasts. During much of the Cold War , Soviet (and Eastern Bloc ) jamming of some Western broadcasters led to a "power race" in which broadcasters and jammers alike repeatedly increased their transmission power, utilised highly directional antennas and added extra frequencies (known as "barrage" or "frequency diversity" broadcasting) to

1710-538: The process of jet formation of high-explosive anti-tank (HEAT) charges, thus maximizing weapon's effectiveness. However, such systems don't allow for a top-attack mode, or target illumination from a different source than the launcher itself, so choice between the two operating modes may vary between operators. The main disadvantage of both SACLOS guidance systems in an anti-tank role is that working on angular differences evaluation, it does not allow any notable separation between guidance system and missile launch post

1755-453: The receiver will begin its state machine to establish two-way data transmission. A jammer will loop back to the beginning instead of completing the handshake. This method jams the receiver in an infinite loop where it keeps trying to initiate a connection but never completes it, which effectively blocks all legitimate communication. Bluetooth and other consumer radio protocols such as WiFi have built-in detectors, so that they transmit only when

1800-436: The tail of the missile looks for the signal. Electronics in the missile then keep it centered in the beam. It differs from semi-active radar homing (SARH) and semi-active laser homing (SALH) in which the target is illuminated by a powerful emitter, and a sensor in the head of missile detects the reflected emissions and directs it to the target. Radar was the most common form of SACLOS signals in early systems, because, in

1845-466: The wires. Also, wires leave a trace all the way to the target, which could help find the source of the fire. Note that almost all (unless counter counter measures are installed) wire/radio link guided ATGMs can be jammed with electro-optical interference emitters such as " Shtora-1 " on the T-90a . With beam-riding SACLOS, the sighting device emits a directional signal directed toward the target. A detector in

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1890-432: Was also one of the main advantages over concurrent SALH systems regarding detection: a laser riding beam emitter is typically a low powered device and does not need to be pointed immediately to the target. Because the missile sensor looks backward to it, the whole system is also impervious to most jamming devices. Another advantage in antitank applications is that the backward-looking guidance system does not interfere with

1935-532: Was more precisely a spoofing attack than jamming. Radar jamming is also important to disrupt use of radar used to guide an enemy's missiles or aircraft . Modern secure communication techniques use such methods as spread spectrum modulation to resist the deleterious effects of jamming. Jamming of foreign radio broadcast stations has often been used in wartime (and during periods of tense international relations) to prevent or deter citizens from listening to broadcasts from enemy countries. However, such jamming

1980-470: Was of limited effectiveness. Groundwave jamming was more effective but only over a small area and was thus used only in/near major cities throughout the Eastern Bloc. Both types of jamming were less effective on higher shortwave frequencies (above 15 MHz); however, many radios sold on the domestic market in the Soviet Union didn't tune these higher bands. Skywave jamming was usually accompanied by morse signals in order to enable (coded) identification of

2025-589: Was the most important clandestine broadcaster in Spain and the regime considered it a threat, since it allowed its citizens to skip the censorship of the local media. Broadcasts from East Germany to South Africa were also jammed. In Latin America there were instances of communist radio stations such as Radio Venceremos being jammed, allegedly by the CIA , while there were short lived instances where Britain jammed some Egyptian (during

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