Радиопомехи: история и методы противодействия

Interference with authorized wireless communications
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 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.

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 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 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 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 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, 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 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

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 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.

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.

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.

Since the early 1960s, the practice of radio jamming has been very common in Cuba, blocking not only American government funded radio stations (such as Voice of America) but also Ham radio signals, and stations owned and/or operated by (or selling airtime to) Cuban exile groups transmitting from Miami, such as La Cubanisima, Radio Mambi, WWFE La Poderosa and Cadena Azul. The same practice has been applied to Radio y Televisión Martí, operated by the U. S. Information Agency since 1985. North Korea and South Korea still regularly jam some of each other's radio (and sometimes television) stations. Several Middle Eastern countries (particularly Iran) jam shortwave broadcasts (and even occasionally attempt to jam satellite TV signals) targeted at their countries. Pakistan has contemplated jamming pirate radio stations operated by the Taliban 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 and Eritrean radio stations. Vietnam jams the Vietnamese service of Radio Free Asia, Radio Đáp Lời Song Núi, some FEBC programs, mostly in Vietnamese Minority languages as well as Radio Sweden with a "siren" jammer and "bubble" jammer on FM Frequencies. In Nigeria, the Nigerian Broadcasting Commission has claimed jamming signal of Radio Biafra. In South Africa, 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 Singapore, a local Indonesian Batam Hang FM 106.0 MHz based Islamic radio station of Indonesia radio stations has jammed Somewhat it transmits up to Singapore and Johor Bahru of Malaysia at 10 kW transmission power. Hang FM 106.0 MHz was accused by Singapore authorities for spreading extremists and terrorism propaganda, there were 4 Singaporeans detained by police under the Internal Security Act (ISA) when they attempted to move to Syria and join ISIS terrorist group. Radio Hang FM has denied this accusation. Station Manager of Hang FM Radio, Abu Yusuf, firmly rejects Hang FM Radio being linked as a media that triggers radicalism. According to him, the broadcast material is also in accordance with the understanding of Ahlussunnah wal Jamaah, which apart from rejecting radicalism, terrorism, especially ISIS, also rejects other ideas or actions that are contrary to the basic principles of the peace loving Islamic religion. Meanwhile, Deputy Chair of the Riau Islands Regional Indonesian Broadcasting Commission (KPID), Suyono, said that while under KPID supervision, in its broadcasts Radio Hang FM actually rejected radicalism and terrorism. Hang FM must decrease its transmission power from 10 kW to 2 kW as its service area is only in Batam. In the future, after radio frequency jamming, Singapore may ban Hang FM website, this will cause listeners cannot access Hang FM via online, even mobile app in Singapore.

Radio jamming (or "comm jamming") 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 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".