HOME

TheInfoList



OR:

Radio jamming is the deliberate jamming, blocking or interference with
wireless communications Wireless communication (or just wireless, when the context allows) is the transfer of information between two or more points without the use of an electrical conductor, optical fiber or other continuous guided medium for the transfer. The most ...
.https://apps.fcc.gov/edocs_public/attachmatch/DA-12-347A1.pdf Enforcement Advisory No. 2012-02 FCC Enforcement Advisory Cell Jammers, GPS Jammers, and Other Jamming Devices Consumer Alert: Using or Importing Jammers is Illegal In some cases, jammers work by the transmission of
radio signal Radio waves are a type of electromagnetic radiation with the longest wavelengths in the electromagnetic spectrum, typically with frequencies of 300 gigahertz ( GHz) and below. At 300 GHz, the corresponding wavelength is 1 mm (shor ...
s that disrupt
communications Communication (from la, communicare, meaning "to share" or "to be in relation with") is usually defined as the transmission of information. The term may also refer to the message communicated through such transmissions or the field of inquir ...
by decreasing the
signal-to-noise ratio Signal-to-noise ratio (SNR or S/N) is a measure used in science and engineering that compares the level of a desired signal to the level of background noise. SNR is defined as the ratio of signal power to the noise power, often expressed in de ...
. 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 a busy
frequency Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from ''angular frequency''. Frequency is measured in hertz (Hz) which is eq ...
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 Cable television is a system of delivering television programming to consumers via radio frequency (RF) signals transmitted through coaxial cables, or in more recent systems, light pulses through fibre-optic cables. This contrasts with bro ...
plant that accidentally emits on an aircraft emergency frequency.


Distinction between "jamming" and "interference"

Originally the terms were used interchangeably but nowadays most radio users use the term "jamming" to describe 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 Electromagnetic compatibility (EMC) is the ability of electrical equipment and systems to function acceptably in their electromagnetic environment, by limiting the unintentional generation, propagation and reception of electromagnetic energy whic ...
.


Method

Intentional communications jamming is usually aimed at radio signals to disrupt control of a battle. A
transmitter In electronics and telecommunications, a radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna. The transmitter itself generates a radio frequency alternating current, which is applied to the ...
, tuned to the same frequency as the opponents' receiving equipment and with the same type of
modulation In electronics and telecommunications, modulation is the process of varying one or more properties of a periodic waveform, called the '' carrier signal'', with a separate signal called the ''modulation signal'' that typically contains informat ...
, can, with enough power, override any signal at the receiver. Digital wireless jamming for signals such as
Bluetooth Bluetooth is a short-range wireless technology standard that is used for exchanging data between fixed and mobile devices over short distances and building personal area networks (PANs). In the most widely used mode, transmission power is limi ...
and
WiFi Wi-Fi () is a family of wireless network protocols, based on the IEEE 802.11 family of standards, which are commonly used for local area networking of devices and Internet access, allowing nearby digital devices to exchange data by radio wa ...
is possible with very low power. The most common types of this form of signal jamming are
random noise In electronics, noise is an unwanted disturbance in an electrical signal. Noise generated by electronic devices varies greatly as it is produced by several different effects. In particular, noise is inherent in physics, and central to the ...
, 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 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 signal to enable individual transmitters to be identified in order to assess their effectiveness. For example, China, which used jamming extensively and still does, plays a loop of
traditional Chinese music ''Guoyue'' ( 國 樂; literally "national music"; also ''minyue'' (民乐), ''huayue'' (華樂) or ''zhongyue'' (中樂)), nowadays refers to the music composed for Chinese musical instruments, which is an extension of the Chinese traditional ...
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 A diesel generator (DG) (also known as a diesel Genset) is the combination of a diesel engine with an electric generator (often an alternator) to generate electrical energy. This is a specific case of engine generator. A diesel compression-ig ...
that was powering the jamming transmitter. Subtle jamming 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 In a radio receiver, the capture effect, or FM capture effect, is a phenomenon associated with FM reception in which only the stronger of two signals at, or near, the same frequency or channel will be demodulated. FM phenomenon The capture ...
,
frequency modulated Frequency modulation (FM) is the encoding of information in a carrier wave by varying the instantaneous frequency of the wave. The technology is used in telecommunications, radio broadcasting, signal processing, and computing. In analog freq ...
broadcasts may be jammed, unnoticed, by a simple unmodulated carrier. The receiver locks on to the larger carrier signal, and hence will ignore the FM signal that carries the information. Digital signals use complex modulation techniques, such as
QPSK Phase-shift keying (PSK) is a digital modulation process which conveys data by changing (modulating) the phase of a constant frequency reference signal (the carrier wave). The modulation is accomplished by varying the sine and cosine inputs ...
. 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, 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 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.


Types of jammers

* Portable jammers are phone-sized and low-powered devices. They can block data delivery at a distance up to 15 meters without barriers. * Stationary jammers are more expensive and powerful. They usually have a larger jamming radius and wider frequency band. Strong jammers can require additional cooling as they can overheat. Stationary jammers usually have a range of 100 meters and require a power supply of 230 V. * Self-made jammers are low-power devices that work over short ranges. However, the coverage can be extended using broadband amplifiers.


History

During World War II, ground radio operators would attempt to mislead pilots by false instructions in their own language, in what was more precisely a
spoofing attack In the context of information security, and especially network security, a spoofing attack is a situation in which a person or program successfully identifies as another by falsifying data, to gain an illegitimate advantage. Internet Spoofing and ...
than jamming.
Radar jamming Radar jamming and deception is a form of electronic countermeasures that intentionally sends out radio frequency signals to interfere with the operation of radar by saturating its receiver with noise or false information. Concepts that blanket ...
is also important to disrupt use of
radar Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, Marine radar, ships, spacecraft, guided missiles, motor v ...
used to guide an enemy's missiles or aircraft. Modern secure communication techniques use such methods as
spread spectrum In telecommunication and radio communication, spread-spectrum techniques are methods by which a signal (e.g., an electrical, electromagnetic, or acoustic signal) generated with a particular bandwidth is deliberately spread in the frequency d ...
modulation to resist the deleterious effects of jamming. Jamming of foreign radio
broadcast Broadcasting is the distribution of audio or video content to a dispersed audience via any electronic mass communications medium, but typically one using the electromagnetic spectrum (radio waves), in a one-to-many model. Broadcasting began wi ...
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 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 World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...
),
Israel Israel (; he, יִשְׂרָאֵל, ; ar, إِسْرَائِيل, ), officially the State of Israel ( he, מְדִינַת יִשְׂרָאֵל, label=none, translit=Medīnat Yīsrāʾēl; ), is a country in Western Asia. It is situated ...
, Cuba, Iraq, Iran (during the Iran-Iraq War), China, North and South Korea and several Latin American countries, as well as by
Ireland Ireland ( ; ga, Éire ; Ulster-Scots: ) is an island in the North Atlantic Ocean, in north-western Europe. It is separated from Great Britain to its east by the North Channel, the Irish Sea, and St George's Channel. Ireland is the s ...
against
pirate radio Pirate radio or a pirate radio station is a radio station that broadcasts without a valid license. In some cases, radio stations are considered legal where the signal is transmitted, but illegal where the signals are received—especially ...
stations such as Radio Nova. The United Kingdom government used two coordinated, separately located transmitters to jam the
offshore radio Offshore radio is radio broadcasting from ships or fixed maritime structures. Offshore broadcasters are usually unlicensed but transmissions are legal in international waters. This is in contrast to unlicensed broadcasting on land or within a na ...
ship, Radio North Sea International off the coast of Britain in 1970.


World War II

In occupied Europe the
Nazi Nazism ( ; german: Nazismus), the common name in English for National Socialism (german: Nationalsozialismus, ), is the far-right totalitarian political ideology and practices associated with Adolf Hitler and the Nazi Party (NSDAP) in ...
s attempted to jam broadcasts to the continent from the BBC and other allied stations. Along with increasing
transmitter In electronics and telecommunications, a radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna. The transmitter itself generates a radio frequency alternating current, which is applied to the ...
power and adding extra frequencies, attempts were made to counteract the jamming by dropping leaflets over cities instructing listeners to construct 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 filter").


Cold War era

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 Voice of America (VOA or VoA) is the State media, state-owned news network and International broadcasting, international radio broadcaster of the United States, United States of America. It is the largest and oldest U.S.-funded international br ...
(VOA) and especially
RFE/RL Radio Free Europe/Radio Liberty (RFE/RL) is a United States government funded organization that broadcasts and reports news, information, and analysis to countries in Eastern Europe, Central Asia, Caucasus, and the Middle East where it says tha ...
. Western nations had allowed jamming prior to World War II , but in the post-War era the Western view has been that jamming violates the
freedom of information Freedom of information is freedom of a person or people to publish and consume information. Access to information is the ability for an individual to seek, receive and impart information effectively. This sometimes includes "scientific, indigen ...
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 The Cold War is a term commonly used to refer to a period of geopolitical tension between the United States and the Soviet Union and their respective allies, the Western Bloc and the Eastern Bloc. The term '' cold war'' is used because t ...
,
Soviet The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, ...
(and
Eastern Bloc The Eastern Bloc, also known as the Communist Bloc and the Soviet Bloc, was the group of socialist states of Central and Eastern Europe, East Asia, Southeast Asia, Africa, and Latin America under the influence of the Soviet Union that existed du ...
) 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 the already heavily overcrowded
shortwave Shortwave radio is radio transmission using shortwave (SW) radio frequencies. There is no official definition of the band, but the range always includes all of the high frequency band (HF), which extends from 3 to 30 MHz (100 to 10 me ...
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 China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...
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 *
Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelag ...
(worst affected, including
mediumwave Medium wave (MW) is the part of the medium frequency (MF) radio band used mainly for AM radio broadcasting. The spectrum provides about 120 channels with more limited sound quality than FM stations on the FM broadcast band. During the dayt ...
frequencies particularly 720 kHz used by RFE) *
North Asia North Asia or Northern Asia, also referred to as Siberia, is the northern region of Asia, which is defined in geographical terms and is coextensive with the Asian part of Russia, and consists of three Russian regions east of the Ural Mountains ...
, Americas and Sub-Saharan Africa (partly affected) *
Australasia Australasia is a region that comprises Australia, New Zealand and some neighbouring islands in the Pacific Ocean. The term is used in a number of different contexts, including geopolitically, physiogeographically, philologically, and ecologic ...
, South America (rarely affected) Meanwhile, some listeners in the Soviet Union and Eastern Bloc devised ingenious methods (such as homemade directional
loop antenna A loop antenna is a radio antenna consisting of a loop or coil of wire, tubing, or other electrical conductor, that is usually fed by a balanced source or feeding a balanced load. Within this physical description there are two (possibly three) ...
s) to hear the Western stations through the noise. Because
radio propagation Radio propagation is the behavior of radio waves as they travel, or are propagated, from one point to another in vacuum, or into various parts of the atmosphere. As a form of electromagnetic radiation, like light waves, radio waves are affect ...
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 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 In radio communication, skywave or skip refers to the propagation of radio waves reflected or refracted back toward Earth from the ionosphere, an electrically charged layer of the upper atmosphere. Since it is not limited by the curvature o ...
jamming covered a large area but for the reasons described was of limited effectiveness.
Groundwave In physics, a surface wave is a mechanical wave that propagates along the interface between differing media. A common example is gravity waves along the surface of liquids, such as ocean waves. Gravity waves can also occur within liquids, at t ...
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 in the Soviet Union didn't cover the higher bands. Skywave jamming was usually accompanied by morse signals in order to enable (coded) identification of 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 Radio Free Europe/Radio Liberty (RFE/RL) is a United States government funded organization that broadcasts and reports news, information, and analysis to countries in Eastern Europe, Central Asia, Caucasus, and the Middle East where it says tha ...
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 the Soviet Union itself
Bulgaria Bulgaria (; bg, България, Bǎlgariya), officially the Republic of Bulgaria,, ) is a country in Southeast Europe. It is situated on the eastern flank of the Balkans, and is bordered by Romania to the north, Serbia and North Macedo ...
was one of the most prolific operators of jamming transmitters in the Eastern bloc with
East Germany East Germany, officially the German Democratic Republic (GDR; german: Deutsche Demokratische Republik, , DDR, ), was a country that existed from its creation on 7 October 1949 until German reunification, its dissolution on 3 October 1990. In t ...
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 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 Francoist Spain ( es, España franquista), or the Francoist dictatorship (), was the period of Spanish history between 1939 and 1975, when Francisco Franco ruled Spain after the Spanish Civil War with the title . After his death in 1975, Spani ...
the dictatorship jammed for decades Radio España Independiente, the radio station of the
Communist Party of Spain The Communist Party of Spain ( es, Partido Comunista de España; PCE) is a Marxist-Leninist party that, since 1986, has been part of the United Left coalition, which is part of Unidas Podemos. It currently has two of its politicians serving a ...
which broadcast from
Moscow Moscow ( , US chiefly ; rus, links=no, Москва, r=Moskva, p=mɐskˈva, a=Москва.ogg) is the capital and largest city of Russia. The city stands on the Moskva River in Central Russia, with a population estimated at 13.0 million ...
(1941–1955) and
Bucharest Bucharest ( , ; ro, București ) is the capital and largest city of Romania, as well as its cultural, industrial, and financial centre. It is located in the southeast of the country, on the banks of the Dâmbovița River, less than north o ...
(1955–1977). It 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. However, in Latin America there were instances of communist radio stations such as Radio Venceremos being jammed, allegedly by the
CIA The Central Intelligence Agency (CIA ), known informally as the Agency and historically as the Company, is a civilian foreign intelligence service of the federal government of the United States, officially tasked with gathering, processing, ...
, while there were short lived instances where Britain jammed some Egyptian (during the
Suez Crisis The Suez Crisis, or the Second Arab–Israeli war, also called the Tripartite Aggression ( ar, العدوان الثلاثي, Al-ʿUdwān aṯ-Ṯulāṯiyy) in the Arab world and the Sinai War in Israel,Also known as the Suez War or 1956 Wa ...
),
Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...
(prior to
Cyprus Cyprus ; tr, Kıbrıs (), officially the Republic of Cyprus,, , lit: Republic of Cyprus is an island country located south of the Anatolian Peninsula in the eastern Mediterranean Sea. Its continental position is disputed; while it is ...
gaining independence) and
Rhodesia Rhodesia (, ), officially from 1970 the Republic of Rhodesia, was an unrecognised state in Southern Africa from 1965 to 1979, equivalent in territory to modern Zimbabwe. Rhodesia was the ''de facto'' successor state to the British colony of So ...
n stations.


Post Cold War (1989–present)


China

In 2002, China acquired standard short-wave radio-broadcasting equipment designed for general public radio-broadcasting and technical support from Thales Broadcast Multimedia, a former subsidiary of the French state-owned company
Thales Group Thales Group () is a French multinational company that designs, develops and manufactures electrical systems as well as devices and equipment for the aerospace, defence, transportation and security sectors. The company is headquartered in Pari ...
. * Thales jamming technology operates only at power levels below 500 kW (for its shortwave jamming products). * Adele Milna (BSEE) of Continental Electronics (in an audio file held at shortwave.org) claims that China has duplicated his company's 100 kW, 250 kW shortwave transmitters. It is unclear if these products were indeed duplicated or if broadcast jamming (as opposed to future product sales) were a reason for the duplication.


Iran

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 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 The Islamic Revolutionary Guard Corps (IRGC; fa, سپاه پاسداران انقلاب اسلامی, Sepāh-e Pāsdārān-e Enghelāb-e Eslāmi, lit=Army of Guardians of the Islamic Revolution also Sepāh or Pasdaran for short) is a branch o ...
is the organization behind satellite jamming in Iran.


Russia

The
Russian Armed Forces The Armed Forces of the Russian Federation (, ), commonly referred to as the Russian Armed Forces, are the military forces of Russia. In terms of active-duty personnel, they are the world's fifth-largest military force, with at least two m ...
have, since the summer of 2015, begun using a multi-functional EW weapon system in
Ukraine Ukraine ( uk, Україна, Ukraïna, ) is a country in Eastern Europe. It is the second-largest European country after Russia, which it borders to the east and northeast. Ukraine covers approximately . Prior to the ongoing Russian inva ...
, known as
Borisoglebsk 2 The Borisoglebsk 2 is a Russian, MT-LBu ground vehicle mounted, multi-functional electronic warfare (EW) weapon system. It was developed by Sozvezdie over a six-year period, from 2004 to 2010. The system was however not ordered, or for other rea ...
. It is postulated that this system has defeated communications in parts of that country, including mobile telephony and GPS systems.


Other countries

* Since the early 1960s, the practice of radio jamming has been very common in
Cuba Cuba ( , ), officially the Republic of Cuba ( es, República de Cuba, links=no ), is an island country comprising the island of Cuba, as well as Isla de la Juventud and several minor archipelagos. Cuba is located where the northern Caribb ...
, blocking not only American government funded radio stations (such as
Voice of America Voice of America (VOA or VoA) is the State media, state-owned news network and International broadcasting, international radio broadcaster of the United States, United States of America. It is the largest and oldest U.S.-funded international br ...
) but also
Ham radio Amateur radio, also known as ham radio, is the use of the radio frequency spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport, contesting, and emergency communica ...
signals, and stations owned and/or operated by (or selling airtime to)
Cuban exile A Cuban exile is a person who emigrated from Cuba in the Cuban exodus. Exiles have various differing experiences as emigrants depending on when they migrated during the exodus. Demographics Social class Cuban exiles would come from various ec ...
groups transmitting from
Miami Miami ( ), officially the City of Miami, known as "the 305", "The Magic City", and "Gateway to the Americas", is a coastal metropolis and the county seat of Miami-Dade County in South Florida, United States. With a population of 442,241 at ...
, such as La Cubanisima, Radio Mambi,
WWFE WWFE (670 AM), known as "La Poderosa", is a commercial radio station in Miami, Florida, broadcasting to the Miami-Fort Lauderdale area. WWFE has a Spanish language talk radio format, with an emphasis on Cuban news and music. The radio studio ...
La Poderosa and Cadena Azul. The same practice has been applied to
Radio y Televisión Martí Radio Televisión Martí is an American state-run radio and television international broadcaster based in Miami, Florida, financed by the federal government of the United States through the U.S. Agency for Global Media (formerly Broadcasting Board ...
, operated by the U.S. Information Agency since 1985. *
North Korea North Korea, officially the Democratic People's Republic of Korea (DPRK), is a country in East Asia. It constitutes the northern half of the Korean Peninsula and shares borders with China and Russia to the north, at the Yalu (Amnok) and T ...
and
South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korea, Korean Peninsula and sharing a Korean Demilitarized Zone, land border with North Korea. Its western border is formed ...
still regularly jam some of each other's radio (and sometimes television) stations. * Several Middle Eastern countries (particularly
Iran Iran, officially the Islamic Republic of Iran, and also called Persia, is a country located in Western Asia. It is bordered by Iraq and Turkey to the west, by Azerbaijan and Armenia to the northwest, by the Caspian Sea and Turkmeni ...
) jam shortwave broadcasts (and even occasionally attempt to jam satellite TV signals) targeted at their countries. * Pakistan has contemplated jamming
pirate radio Pirate radio or a pirate radio station is a radio station that broadcasts without a valid license. In some cases, radio stations are considered legal where the signal is transmitted, but illegal where the signals are received—especially ...
stations operated by the
Taliban The Taliban (; ps, طالبان, ṭālibān, lit=students or 'seekers'), which also refers to itself by its state (polity), state name, the Islamic Emirate of Afghanistan, is a Deobandi Islamic fundamentalism, Islamic fundamentalist, m ...
in all jails across Pakistan. This decision has led to an outcry from Pakistani cellular operators, who state that most of the jails lie in urban areas with a resultant impact on the cellular service of all operators in the adjacent area of jails. * Ethiopia has jammed the DW and VOA transmissions as well as
ESAT Ethiopian Satellite Television (ESAT) is an Ethiopian satellite news network headquartered in Washington D.C., United States. It is a nonprofit and independent media outlet mostly privately funded by donors from the broader Ethiopian diaspora. ...
Ethiopian Satellite Television and
Eritrea Eritrea ( ; ti, ኤርትራ, Ertra, ; ar, إرتريا, ʾIritriyā), officially the State of Eritrea, is a country in the Horn of Africa region of Eastern Africa, with its capital and largest city at Asmara. It is bordered by Ethiopi ...
n radio stations. * Vietnam jams the Vietnamese service of
Radio Free Asia Radio Free Asia (RFA) is a United States government-funded private non-profit news service that broadcasts radio programs and publishes online news, information, and commentary for its audiences in Asia. The service, which provides editoria ...
, Radio Đáp Lời Song Núi, some FEBC programs, mostly in Vietnamese Minority languages as well as
Radio Sweden Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmit ...
with a "siren" jammer and "bubble" jammer on FM Frequencies. * In Nigeria, the
Nigerian Broadcasting Commission The National Broadcasting Commission is the broadcast regulator of the Federal Republic of Nigeria. The commission was set up on August 24, 1992, by Decree 38 of 1992 later amended as an act of the National Assembly by Act 55 of 1999 and now known ...
has claimed jamming signal of Radio
Biafra Biafra, officially the Republic of Biafra, was a partially recognised secessionist state in West Africa that declared independence from Nigeria and existed from 1967 until 1970. Its territory consisted of the predominantly Igbo-populated f ...
. * In
South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring coun ...
, the use of wireless signal jammers is illegal. There is a single exception to this rule. South Africa's State Security Cluster may, in certain instances, employ signal jammers.


In fiction

Radio jamming (or "comm jamming") is a common plot element in the ''
Star Wars ''Star Wars'' is an American epic space opera multimedia franchise created by George Lucas, which began with the eponymous 1977 film and quickly became a worldwide pop-culture phenomenon. The franchise has been expanded into various film ...
'' franchise. In ''Star Wars: Episode VI -
Return of the Jedi ''Return of the Jedi'' (also known as ''Star Wars: Episode VI – Return of the Jedi'' is a 1983 American epic space opera film directed by Richard Marquand. The screenplay is by Lawrence Kasdan and George Lucas from a story by Lucas, who ...
'', 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 the space station ''Regula I'', Captain Kirk attempts to establish communications, but the ''Enterprise's'' comm officer Lt. Uhura reports that further transmissions are "jammed at the source".


See also

*
Radar jamming and deception Radar jamming and deception is a form of electronic countermeasures that intentionally sends out radio frequency signals to interfere with the operation of radar by saturating its receiver with noise or false information. Concepts that blanket the ...
*
Association of Old Crows The Association of Old Crows is an international nonprofit professional organization specializing in electronic warfare, tactical information operations, and associated disciplines headquartered in Alexandria, Virginia. Its mission is to "advocat ...
*
Culture jamming Culture jamming (sometimes also guerrilla communication) is a form of protest used by many anti-consumerist social movements to disrupt or subvert media culture and its mainstream cultural institutions, including corporate advertising. It att ...
*
Electronic warfare Electronic warfare (EW) is any action involving the use of the electromagnetic spectrum (EM spectrum) or directed energy to control the spectrum, attack an enemy, or impede enemy assaults. The purpose of electronic warfare is to deny the opponent ...
*
Eastern Bloc information dissemination Eastern Bloc media and propaganda was controlled directly by each country's communist party, which controlled the state media, censorship and propaganda organs. State and party ownership of print, television and radio media served as an important ...
*
Mobile phone jammer A mobile phone jammer or blocker is a device which deliberately transmits signals on the same radio frequencies as mobile phones, disrupting the communication between the phone and the cell-phone base station, effectively disabling mobile phones wi ...
*
Microphone blocker A microphone blocker is a phone microphone connector used to trick feature phones that have a physical microphone switch to disconnect the microphone. Microphone blockers won't operate on smartphones or laptops because the microphone is controlle ...
*
Radio jamming in China Radio jamming in China is a form of censorship in the People's Republic of China that involves deliberate attempts by state or Communist Party organs to interfere with radio broadcasts. In most instances, radio jamming targets foreign broadcasters ...
*
Radio jamming in Korea Radio jamming on the Korean Peninsula makes the border region one of the world's busiest places for radio signals. Medium wave jamming is dominant in the area including Seoul and the Korean Demilitarized Zone (DMZ). South Korea jams all radio and ...


References


External links


extensive site on radio jamming

Article on recent jammers with audio samples

Audio sample of jamming (c1982) at start of BBC World service (Russian) programme
includes jamming station morse ID
Ethiopia jams VOA (2010)

Ultra Fast Folloow Jammer Description (2007)

R. Pleikys, D. Vildžiūnas. Empire of Noise (video).

Aadu Jogiaas: Disturbing soviet transmissions in August 1991.


* Words: Matt Bolton, Photographs: Matt Munr
The Tallinn Cables, A Glimpse Into Tallainn's Secret History of Espionage
''Lonely Planet Magazine'', December 2011 {{Censorship Electronic countermeasures Radio technology Denial-of-service attacks Censorship of broadcasting