73-472: Medium frequency ( MF ) is the ITU designation for radio frequencies (RF) in the range of 300 kilohertz (kHz) to 3 megahertz (MHz). Part of this band is the medium wave (MW) AM broadcast band. The MF band is also known as the hectometer band as the wavelengths range from ten to one hectometers (1000 to 100 m). Frequencies immediately below MF are denoted as low frequency (LF), while
146-1009: A dipole reception pattern with sharp nulls along the axis of the rod, so that reception is at its best when the rod is at right angles to the transmitter, but fades to nothing when the rod points exactly at the transmitter. Other types of loop antennas and random wire antennas are also used. ELF 3 Hz/100 Mm 30 Hz/10 Mm SLF 30 Hz/10 Mm 300 Hz/1 Mm ULF 300 Hz/1 Mm 3 kHz/100 km VLF 3 kHz/100 km 30 kHz/10 km LF 30 kHz/10 km 300 kHz/1 km MF 300 kHz/1 km 3 MHz/100 m HF 3 MHz/100 m 30 MHz/10 m VHF 30 MHz/10 m 300 MHz/1 m UHF 300 MHz/1 m 3 GHz/100 mm SHF 3 GHz/100 mm 30 GHz/10 mm EHF 30 GHz/10 mm 300 GHz/1 mm THF 300 GHz/1 mm 3 THz/0.1 mm International Telecommunication Union The International Telecommunication Union (ITU)
219-405: A loading coil at their base. Receiving antennas do not have to be as efficient as transmitting antennas since in this band the signal-to-noise ratio is determined by atmospheric noise. The noise floor in the receiver is far below the noise in the signal, so antennas small in comparison to the wavelength, which are inefficient and produce low signal strength, can be used. The weak signal from
292-472: A 2.8 kHz sliver of spectrum from 71.6 kHz to 74.4 kHz beginning in April ;1996 to UK amateurs who applied for a Notice of Variation to use the band on a noninterference basis with a maximum output power of 1 Watt ERP . This was withdrawn on 30 June 2003 after a number of extensions in favor of the cross-European standard 136 kHz band. Very slow Morse Code from G3AQC in
365-527: A band from 190 to 435 kHz, which overlaps from the LF into the bottom part of the MF band. 2182 kHz is the international calling and distress frequency for SSB maritime voice communication (radiotelephony). It is analogous to Channel 16 on the marine VHF band. 500 kHz was for many years the maritime distress and emergency frequency , and there are more NDBs between 510 and 530 kHz. Navtex , which
438-463: A built-in pre-amplifier . Due to the long wavelengths in the band, nearly all LF antennas are electrically short , shorter than one quarter of the radiated wavelength, so their low radiation resistance makes them inefficient, requiring very low resistance grounds and conductors to avoid dissipating transmitter power. These electrically short antennas need loading coils at the base of the antenna to bring them into resonance. Many antenna types, such as
511-449: A country code, being listed as "Taiwan, China." In addition to the 194 Member States, the ITU includes close to 900 "sector members"—private organizations like carriers, equipment manufacturers, media companies, funding bodies, research and development organizations, and international and regional telecommunication organizations. While nonvoting, these members may still play a role in shaping
584-578: A different aspect of the matters covered by the ITU, as well as ITU Telecom. The sectors were created during the restructuring of ITU at the additional 1992 ITU Plenipotentiary Conference . A permanent General Secretariat, headed by the Secretary General, manages the day-to-day work of the ITU and its sectors. The basic texts of the ITU are adopted by the ITU Plenipotentiary Conference. The founding document of
657-440: A ground system consisting of many copper cables, buried shallowly in the earth, radiating from the base of the antenna to a distance of about a quarter wavelength. In areas of rocky or sandy soil where the ground conductivity is poor, above-ground counterpoises are sometimes used. Lower power transmitters often use electrically short quarter wave monopoles such as inverted-L or T antennas , which are brought into resonance with
730-619: A height around 100 meters are used. T-antennas have a height between 50–200 meters, while mast aerials are usually taller than 150 meters. The height of mast antennas for LORAN-C is around 190 meters for transmitters with radiated power below 500 kW, and around 400 meters for transmitters greater than 1 000 kilowatts. The main type of LORAN-C antenna is insulated from ground. LF (longwave) broadcasting stations use mast antennas with heights of more than 150 meters or T-aerials . The mast antennas can be ground-fed insulated masts or upper-fed grounded masts. It
803-421: A number of frequencies, varying by country, between 120–148 kHz. Some radio frequency identification ( RFID ) tags utilize LF. These tags are commonly known as LFIDs or LowFIDs (low frequency identification). The LF RFID tags are near-field devices, interacting with the inductive near field , rather than with radiated waves (radio waves) that are the only part of the electromagnetic field that persists into
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#1732772322770876-646: A resolution on Internet governance that called for government participation in Internet topics at various ITU forums. Despite the significant number countries not signing, the ITU came out with a press release: "New global telecoms treaty agreed in Dubai". The conference was managed by the International Telecommunication Union (ITU). While certain parts of civil society and industry were able to advise and observe, active participation
949-533: A sensitive nature might be shared. Telecommunications ministers from 193 countries attended the conference in Dubai. The current regulatory structure was based on voice telecommunications, when the Internet was still in its infancy. In 1988, telecommunications operated under regulated monopolies in most countries. As the Internet has grown, organizations such as ICANN have come into existence for management of key resources such as Internet addresses and domain names . Current proposals look to take into account
1022-671: A single entity, the International Telecommunication Union. The Conference decided that the Telegraph Convention of 1875 and the Radiotelegraph Convention of 1927 were to be combined into a single convention, the International Telecommunication Convention, embracing the three fields of telegraphy, telephony and radio. On 15 November 1947, an agreement between ITU and the newly created United Nations recognized
1095-454: A sudden halt in transmission, particularly of the morning news programme Today , as an indicator that the UK is under attack, whereafter their sealed orders take effect. The United States has four LF stations maintaining contact with its submarine force: Aguada, Puerto Rico , Keflavik, Iceland , Awase, Okinawa , and Sigonella, Italy , using AN/FRT-95 solid state transmitters. In the U.S.,
1168-524: A threat to the "...free and open internet." On 22 November 2012, the European Parliament passed a resolution urging member states to prevent ITU WCIT-12 activity that would "negatively impact the internet, its architecture, operations, content and security, business relations, internet governance and the free flow of information online". The resolution asserted that "the ITU [...] is not the appropriate body to assert regulatory authority over
1241-530: Is AM broadcasting ; AM radio stations are allocated frequencies in the medium wave broadcast band from 526.5 kHz to 1606.5 kHz in Europe; in North America this extends from 525 kHz to 1705 kHz Some countries also allow broadcasting in the 120-meter band from 2300 to 2495 kHz; these frequencies are mostly used in tropical areas. Although these are medium frequencies, 120 meters
1314-462: Is ground waves , in which LF radio waves travel just above the Earth's surface, following the terrain. LF ground waves can travel over hills, and can travel far beyond the horizon, up to several hundred kilometers from the transmitter. Because of their long wavelength , low frequency radio waves can diffract over obstacles like mountain ranges and travel beyond the horizon, following the contour of
1387-770: Is a specialized agency of the United Nations responsible for many matters related to information and communication technologies . It was established on 17 May 1865 as the International Telegraph Union , significantly predating the UN and making it the oldest UN agency. Doreen Bogdan-Martin is the Secretary-General of ITU, the first woman to serve as its head. The ITU was initially aimed at helping connect telegraphic networks between countries, with its mandate consistently broadening with
1460-586: Is also known as the kilometre band or kilometre wave s. LF radio waves exhibit low signal attenuation , making them suitable for long-distance communications. In Europe and areas of Northern Africa and Asia, part of the LF spectrum is used for AM broadcasting as the " longwave " band. In the western hemisphere, its main use is for aircraft beacons, navigation ( LORAN , mostly defunct), information, and weather systems. A number of time signal broadcasts also use this band. The main mode of transmission used in this band
1533-439: Is also possible to use cage antennas on grounded masts. For broadcasting stations, directional antennas are often required. They consist of multiple masts, which often have the same height. Some longwave antennas consist of multiple mast antennas arranged in a circle with or without a mast antenna in the center. Such antennas focus the transmitted power toward ground and give a large zone of fade-free reception. This type of antenna
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#17327723227701606-620: Is also referred to as the 1 750 meter band. Requirements include: Many experimenters in this band are amateur radio operators. A regular service transmitting RTTY marine meteorological information in SYNOP code on LF is the German Meteorological Service ( Deutscher Wetterdienst or DWD ). The DWD operates station DDH47 on 147.3 kHz using standard ITA-2 alphabet with a transmission speed of 50 baud and FSK modulation with 85 Hz shift. In parts of
1679-430: Is claimed the proposal would allow government restriction or blocking of information disseminated via the Internet and create a global regime of monitoring Internet communications, including the demand that those who send and receive information identify themselves. It would also allow governments to shut down the Internet, if it is believed that it may interfere in the internal affairs of other states, or that information of
1752-696: Is generally treated as one of the shortwave bands . There are a number of coast guard and other ship-to-shore frequencies in use between 1600 and 2850 kHz. These include, as examples, the French MRCC on 1696 kHz and 2677 kHz, Stornoway Coastguard on 1743 kHz, the US Coastguard on 2670 kHz and Madeira on 2843 kHz. RN Northwood in England broadcasts Weather Fax data on 2618.5 kHz. Non-directional navigational radio beacons (NDBs) for maritime and aircraft navigation occupy
1825-426: Is lower than at higher frequencies. Low frequency ground waves can be received up to 2,000 kilometres (1,200 mi) from the transmitting antenna. Low frequency waves can also occasionally travel long distances by reflecting from the ionosphere (the actual mechanism is one of refraction ), although this method, called skywave or "skip" propagation, is not as common as at higher frequencies. Reflection occurs at
1898-512: Is part of the current Global Maritime Distress Safety System occupies 518 kHz and 490 kHz for important digital text broadcasts. Lastly, there are aeronautical and other mobile SSB bands from 2850 kHz to 3500 kHz, crossing the boundary from the MF band into the HF radio band. An amateur radio band known as 160 meters or 'top-band' is between 1800 and 2000 kHz (allocation depends on country and starts at 1810 kHz outside
1971-581: Is the first woman to serve as the ITU Secretary-General. Membership of ITU is open to all member states of the United Nations . There are currently 194 member states of the ITU, including all UN member states . The most recent member state to join the ITU is Republic of Palau , which became a member on 19 September 2024. Palestine was admitted as a United Nations General Assembly observer in 2010. Pursuant to UN General Assembly Resolution 2758 (XXVI) of 25 October 1971—which recognized
2044-482: The 2 200 meter band (135.7–137.9 kHz) is available to amateur radio operators in several countries in Europe, New Zealand, Canada, US, and French overseas dependencies. The world record distance for a two-way contact is over 10,000 km from near Vladivostok to New Zealand . As well as conventional Morse code many operators use very slow computer-controlled Morse code (so-called "QRSS" ) or specialized digital communications modes. The UK allocated
2117-527: The Ground Wave Emergency Network or GWEN operated between 150 and 175 kHz, until replaced by satellite communications systems in 1999. GWEN was a land based military radio communications system which could survive and continue to operate even in the case of a nuclear attack. The 2007 World Radiocommunication Conference (WRC-07) made a worldwide amateur radio allocation in this band. An international 2.1 kHz allocation,
2190-654: The People's Republic of China (PRC) as "the only legitimate representative of China to the United Nations"—on 16 June 1972 the ITU Council adopted Resolution No. 693 which "decided to restore all its rights to the People's Republic of China in ITU and recognize the representatives of its Government as the only representatives of China to the ITU ". Taiwan and the territories controlled by the Republic of China (ROC), received
2263-623: The radio spectrum , facilitates international cooperation in assigning satellite orbits , assists in developing and coordinating worldwide technical standards , and works to improve telecommunication infrastructure in the developing world. It is also active in the areas of broadband Internet, optical communications (including optical fiber technologies), wireless technologies, aeronautical and maritime navigation, radio astronomy , satellite-based meteorology, TV broadcasting, amateur radio , and next-generation networks . Based in Geneva , Switzerland,
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2336-496: The umbrella antenna and L- and T-antenna, use capacitive top-loading (a "top hat"), in the form of a network of horizontal wires attached to the top of the vertical radiator. The capacitance improves the efficiency of the antenna by increasing the current, without increasing its height. The height of antennas differ by usage. For some non-directional beacons (NDBs) the height can be as low as 10 meters, while for more powerful navigation transmitters such as DECCA , masts with
2409-600: The 152 countries. Countries that did not sign included the United States, Japan, Canada, France, Germany, New Zealand, India and the United Kingdom. The head of the U.S. delegation, Terry Kramer, said "We cannot support a treaty that is not supportive of the multistakeholder model of Internet governance". The disagreement appeared to be over some language in the revised ITRs referring to ITU roles in addressing unsolicited bulk communications, network security, and
2482-535: The Americas). Amateur operators transmit CW morse code , digital signals and SSB and AM voice signals on this band. Following World Radiocommunication Conference 2012 (WRC-2012), the amateur service received a new allocation between 472 and 479 kHz for narrow band modes and secondary service, after extensive propagation and compatibility studies made by the ARRL 600 meters Experiment Group and their partners around
2555-410: The Earth. This mode of propagation, called ground wave , is the main mode in the LF band. Ground waves must be vertically polarized (the electric field is vertical while the magnetic field is horizontal), so vertical monopole antennas are used for transmitting. The transmission distance is limited by the absorption of ground waves in the Earth. The attenuation of signal strength with distance
2628-614: The General Rules of Conferences, Assemblies and Meetings of the Union. The Plenipotentiary Conference is the supreme organ of the ITU. It is composed of all 194 ITU members and meets every four years. The Conference determines the policies, direction and activities of the Union, as well as elects the members of other ITU organs. While the Plenipotentiary Conference is the Union's main decision-making body,
2701-483: The ITU Council acts as the Union's governing body in the interval between Plenipotentiary Conferences. It meets every year. It is composed of 48 members and works to ensure the smooth operation of the Union, as well as to consider broad telecommunication policy issues. Its members are as follow: The Secretariat is tasked with the administrative and budgetary planning of the Union, as well as with monitoring compliance with ITU regulations, and oversees with assistance from
2774-436: The ITU and some countries has alarmed many within the United States and within the Internet community. Indeed, some European telecommunication services have proposed a so-called "sender pays" model that would require sources of Internet traffic to pay destinations, similar to the way funds are transferred between countries using the telephone. The WCIT-12 activity has been criticized by Google , which has characterized it as
2847-450: The ITU as the specialized agency for global telecommunications. This agreement entered into force on 1 January 1949, officially making the ITU an organ of the United Nations. In December 2012, the ITU facilitated The World Conference on International Telecommunications 2012 (WCIT-12) in Dubai . WCIT-12 was a treaty -level conference to address International Telecommunications Regulations,
2920-650: The ITU was the 1865 International Telegraph Convention, which has since been replaced several times (though the text is generally the same) and is now entitled the "Constitution and Convention of the International Telecommunication Union". In addition to the Constitution and Convention, the consolidated basic texts include the Optional Protocol on the settlement of disputes, the Decisions, Resolutions, Reports and Recommendations in force, as well as
2993-533: The ITU's global membership includes 194 countries and around 900 businesses, academic institutions, and international and regional organizations. The ITU is one of the oldest international organizations still in operation, second only to the Central Commission for Navigation on the Rhine , which predates it by fifty years. It was preceded by the now defunct International Telegraph Union which drafted
Medium frequency - Misplaced Pages Continue
3066-565: The Information Society (WSIS) was convened by the ITU along with UNESCO , UNCTAD , and UNDP , with the aim of bridging the digital divide . It was held in form of two conferences in 2003 and 2005 in Geneva and Tunis, respectively. Low frequency Low frequency ( LF ) is the ITU designation for radio frequencies (RF) in the range of 30–300 kHz . Since its wavelengths range from 10–1 km , respectively, it
3139-637: The International Telegraph Convention which was signed on 17 May 1865. As a result of the 1865 Conference, the International Telegraph Union, the predecessor to the modern ITU, was founded as the first international standards organization. The Union was tasked with implementing basic principles for international telegraphy. This included: the use of the Morse code as the international telegraph alphabet,
3212-604: The Internet ...", and stated that the policy of the United States is "... to promote a global Internet free from government control and preserve and advance the successful Multistakeholder Model that governs the Internet today." The same resolution had previously been passed unanimously by the United States Senate in September. On 14 December 2012, an amended version of the Regulations was signed by 89 of
3285-550: The Internet. In 2022, the U.S. government eased restrictions on SpaceX 's Starlink service in Iran amid the Mahsa Amini protests in order to sidestep widespread internet censorship in the country. The Iranian government subsequently filed a complaint with the ITU in an attempt to prohibit Starlink service in Iran. In October 2023 and March 2024, the ITU ruled in favor of Iran. The ITU comprises three sectors, each managing
3358-569: The Secretariat advisor Neaomy Claiborne of Riverbank to insure misconduct during legal investigations are not overlooked and finally, it publishes the results of the work of the ITU. The Secretariat is headed by a Secretary-General who is responsible for the overall management of the Union, and acts as its legal representative. The Secretary-General is elected by the Plenipotentiary Conference for four-year terms. On 23 October 2014, Houlin Zhao
3431-674: The UK was received 3,275 miles (5,271 km) away, across the Atlantic Ocean , by W1TAG in the US on 21-22 November 2001 on 72.401 kHz. In the United States, there is an exemption within FCC Part ;15 regulations permitting unlicensed transmissions in the frequency range of 160–190 kHz. Longwave radio hobbyists refer to this as the ' LowFER ' band, and experimenters, and their transmitters are called ' LowFERs '. This frequency range between 160 kHz and 190 kHz
3504-449: The advent of new communications technologies; it adopted its current name in 1932 to reflect its expanded responsibilities over radio and the telephone. On 15 November 1947, the ITU entered into an agreement with the newly created United Nations to become a specialized agency within the UN system , which formally entered into force on 1 January 1949. The ITU promotes the shared global use of
3577-548: The antenna can be amplified in the receiver without introducing significant noise. The most common receiving antenna is the ferrite loopstick antenna (also known as a ferrite rod aerial ), made from a ferrite rod with a coil of fine wire wound around it. This antenna is small enough that it is usually enclosed inside the radio case. In addition to their use in AM radios, ferrite antennas are also used in portable radio direction finder (RDF) receivers. The ferrite rod antenna has
3650-551: The convention eventually became known as ITU Radio Regulations . At the conference it was also decided that the Bureau of the International Telegraph Union would also act as the conference's central administrator. Between 3 September and 10 December 1932, a joint conference of the International Telegraph Union and the International Radiotelegraph Union convened to merge the two organizations into
3723-639: The decisions of the Union. The sector members are divided as follow: The ITU is divided into five administrative regions, designed to streamline administration of the organization. They are also used in order to ensure equitable distribution on the council, with seats being apportioned among the regions. They are as follow: The ITU operates six regional offices, as well as seven area offices. These offices help maintain direct contact with national authorities, regional telecommunication organizations and other stakeholders. They are as follow: Other regional organizations connected to ITU are: The World Summit on
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#17327723227703796-400: The earliest international standards and regulations governing international telegraph networks. The development of the telegraph in the early 19th century changed the way people communicated on the local and international levels. Between 1849 and 1865, a series of bilateral and regional agreements among Western European states attempted to standardize international communications. By 1865, it
3869-569: The far field. As such, they are technically not radio devices nor radio antennas, even though they do operate at radio frequencies, and are called "antennas" in the RFID trade, but not in radio engineering . It is more proper, and technically more informative to think of them as secondary coils of very loosely coupled transformers . Since the ground waves used in this band require vertical polarization , vertical antennas are used for transmission. Mast radiators are most common, either insulated from
3942-470: The first band of higher frequencies is known as high frequency (HF). MF is mostly used for AM radio broadcasting , navigational radio beacons , maritime ship-to-shore communication, and transoceanic air traffic control . Radio waves at MF wavelengths propagate via ground waves and reflection from the ionosphere (called skywaves ). Ground waves follow the curvature of Earth . At these wavelengths, they can bend ( diffract ) over hills, and travel beyond
4015-727: The ground and fed at the bottom, or occasionally fed through guy-wires. T-antennas and inverted L-antennas are used when antenna height is an issue. LF transmitting antennas for high power transmitters require large amounts of space, and have been the cause of controversy in Europe and the United States, due to concerns about possible health hazards associated with human exposure to radio waves . Antenna requirements for LF reception are much more modest than for transmission. Although non-resonant long wire antennas are sometimes used, ferrite loop antennas are far more popular because of their small size. Amateur radio operators have achieved good LF reception using active antennas : A short whip with
4088-535: The international rules for telecommunications , including international tariffs . The previous conference to update the Regulations (ITRs) was held in Melbourne in 1988. In August 2012, Neaomy Claiborne of Northern California was reelected for a third term as liaison and legal advisor to the Secretariat General. ITU called for a public consultation on a draft document ahead of the conference. It
4161-487: The internet". On 5 December 2012, the United States House of Representatives passed a resolution opposing UN governance of the Internet by a rare unanimous 397–0 vote. The resolution warned that "... proposals have been put forward for consideration at the [WCIT-12] that would fundamentally alter the governance and operation of the Internet ... [and] would attempt to justify increased government control over
4234-407: The inverted-L and T antennas , and wire dipole antennas . Ground wave propagation, the most widely used type at these frequencies, requires vertically polarized antennas like monopoles. The most common transmitting antennas, monopoles of one-quarter to five-eighths wavelength, are physically large at these frequencies, 25 to 250 metres (82 to 820 ft) requiring a tall radio mast . Usually
4307-491: The ionospheric E layer or F layers . Skywave signals can be detected at distances exceeding 300 kilometres (190 mi) from the transmitting antenna. AM broadcasting is authorized in the longwave band on frequencies between 148.5 and 283.5 kHz in Europe and parts of Asia. In Europe and Japan, many low-cost consumer devices have since the late 1980s contained radio clocks with an LF receiver for these signals. Since these frequencies propagate by ground wave only,
4380-572: The ionospheric D layer can virtually disappear. When this happens, MF radio waves can easily be received hundreds or even thousands of miles away as the signal will be refracted by the remaining F layer. This can be very useful for long-distance communication, but can also interfere with local stations. Because of the limited number of available channels in the MW broadcast band, the same frequencies are re-allocated to different broadcasting stations several hundred miles apart. On nights of good skywave propagation,
4453-478: The longer the wavelength, the deeper they go. The British, German, Indian, Russian, Swedish, United States, and possibly other navies communicate with submarines on these frequencies. In addition, Royal Navy nuclear submarines carrying ballistic missiles are allegedly under standing orders to monitor the BBC Radio 4 transmission on 198 kHz in waters near the UK. It is rumoured that they are to construe
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#17327723227704526-427: The metal mast itself is energized and used as the antenna, and is mounted on a large porcelain insulator to isolate it from the ground; this is called a mast radiator . The monopole antenna, particularly if electrically short requires a good, low resistance Earth ground connection for efficiency since the ground resistance is in series with the antenna and consumes transmitter power. Commercial radio stations use
4599-481: The precision of time signals is not affected by varying propagation paths between the transmitter, the ionosphere, and the receiver. In the United States, such devices became feasible for the mass market only after the output power of WWVB was increased in 1997 and 1999. JJY transmitting broadcast on the exact same frequency, and has a similar timecode . Radio signals below 50 kHz are capable of penetrating ocean depths to approximately 200 metres (660 ft);
4672-491: The prevalence of data communications. Proposals under consideration would establish regulatory oversight by the UN over security, fraud, traffic accounting as well as traffic flow, management of Internet Domain Names and IP addresses , and other aspects of the Internet that are currently governed either by community-based approaches such as regional Internet registries , ICANN, or largely national regulatory frameworks. The move by
4745-573: The protection of the secrecy of correspondence, and the right of everybody to use the international telegraphy. Another predecessor to the modern ITU, the International Radiotelegraph Union, was established in 1906 at the first International Radiotelegraph Convention in Berlin. The conference was attended by representatives of 29 nations and culminated in the International Radiotelegraph Convention. An annex to
4818-531: The signals of distant stations may reflect off the ionosphere and interfere with the signals of local stations on the same frequency. The North American Regional Broadcasting Agreement (NARBA) sets aside certain channels for nighttime use over extended service areas via skywave by a few specially licensed AM broadcasting stations. These channels are called clear channels , and the stations, called clear-channel stations , are required to broadcast at higher powers of 10 to 50 kW. A major use of these frequencies
4891-523: The sky are refracted back to Earth by layers of charged particles ( ions ) in the ionosphere , the E and F layers . However, at certain times the D layer (at a lower altitude than the refractive E and F layers) can be electronically noisy and absorb MF radio waves, interfering with skywave propagation. This happens when the ionosphere is heavily ionised, such as during the day, in summer and especially at times of high solar activity . At night, especially in winter months and at times of low solar activity,
4964-414: The visual horizon, although they may be blocked by mountain ranges. Typical MF radio stations can cover a radius of several hundred kilometres/miles from the transmitter, with longer distances over water and damp earth. MF broadcasting stations use ground waves to cover their listening areas. MF waves can also travel longer distances via skywave propagation, in which radio waves radiated at an angle into
5037-719: The world where there is no longwave broadcasting service, Non-directional beacons used for aeronavigation operate on 190–300 kHz (and beyond into the MW band). In Europe, Asia and Africa, the NDB allocation starts on 283.5 kHz. The LORAN -C radio navigation system operated on 100 kHz. In the past, the Decca Navigator System operated between 70 kHz and 129 kHz. The last Decca chains were closed down in 2000. Differential GPS telemetry transmitters operate between 283.5 and 325 kHz. The commercial " Datatrak " radio navigation system operates on
5110-514: The world. In recent years, some limited amateur radio operation has also been allowed in the region of 500 kHz in the US, UK, Germany and Sweden. Many home-portable or cordless telephones, especially those that were designed in the 1980s, transmit low power FM audio signals between the table-top base unit and the handset on frequencies in the range 1600 to 1800 kHz. Transmitting antennas commonly used on this band include monopole mast radiators , top-loaded wire monopole antennas such as
5183-530: Was agreed that a comprehensive agreement was needed in order to create a framework that would standardize telegraphy equipment, set uniform operating instructions, and lay down common international tariff and accounting rules. Between 1 March and 17 May 1865, the French Government hosted delegations from 20 European states at the first International Telegraph Conference in Paris. This meeting culminated in
5256-633: Was elected as the 19th Secretary-General of the ITU at the Plenipotentiary Conference in Busan . His four-year mandate started on 1 January 2015, and he was formally inaugurated on 15 January 2015. He was re-elected on 1 November 2018 during the 2018 Plenipotentiary Conference in Dubai . On 29 September 2022, Doreen Bogdan-Martin was elected as the 20th Secretary-General of the ITU at the Plenipotentiary Conference in Bucharest, Romania. She received 139 votes out of 172, defeating Russia's Rashid Ismailov. She
5329-436: Was restricted to member states . The Electronic Frontier Foundation expressed concern at this, calling for a more transparent multi-stakeholder process. Some leaked contributions can be found on the web site wcitleaks.org . Google -affiliated researchers have suggested that the ITU should completely reform its processes to align itself with the openness and participation of other multistakeholder organizations concerned with
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