1.
Frequency
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Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as frequency, which emphasizes the contrast to spatial frequency. The period is the duration of time of one cycle in a repeating event, for example, if a newborn babys heart beats at a frequency of 120 times a minute, its period—the time interval between beats—is half a second. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as vibrations, audio signals, radio waves. For cyclical processes, such as rotation, oscillations, or waves, in physics and engineering disciplines, such as optics, acoustics, and radio, frequency is usually denoted by a Latin letter f or by the Greek letter ν or ν. For a simple motion, the relation between the frequency and the period T is given by f =1 T. The SI unit of frequency is the hertz, named after the German physicist Heinrich Hertz, a previous name for this unit was cycles per second. The SI unit for period is the second, a traditional unit of measure used with rotating mechanical devices is revolutions per minute, abbreviated r/min or rpm. As a matter of convenience, longer and slower waves, such as ocean surface waves, short and fast waves, like audio and radio, are usually described by their frequency instead of period. Spatial frequency is analogous to temporal frequency, but the axis is replaced by one or more spatial displacement axes. Y = sin = sin d θ d x = k Wavenumber, in the case of more than one spatial dimension, wavenumber is a vector quantity. For periodic waves in nondispersive media, frequency has a relationship to the wavelength. Even in dispersive media, the frequency f of a wave is equal to the phase velocity v of the wave divided by the wavelength λ of the wave. In the special case of electromagnetic waves moving through a vacuum, then v = c, where c is the speed of light in a vacuum, and this expression becomes, f = c λ. When waves from a monochrome source travel from one medium to another, their remains the same—only their wavelength. For example, if 71 events occur within 15 seconds the frequency is, the latter method introduces a random error into the count of between zero and one count, so on average half a count. This is called gating error and causes an error in the calculated frequency of Δf = 1/, or a fractional error of Δf / f = 1/ where Tm is the timing interval. This error decreases with frequency, so it is a problem at low frequencies where the number of counts N is small, an older method of measuring the frequency of rotating or vibrating objects is to use a stroboscope
2.
Low frequency
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Low frequency or LF is the ITU designation for radio frequencies in the range of 30 kHz–300 kHz. As its wavelengths range from ten kilometres to one kilometre, respectively, 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 beacon, navigation, information, and weather systems. A number of time signal broadcasts are also broadcast in this band, 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 the Earth. This mode of propagation, called ground wave, is the mode in the LF band. Ground waves must be polarized, so monopole antennas are used for transmitting. The attenuation of signal strength with distance by absorption in the ground is lower than at higher frequencies, low frequency ground waves can be received up to 2,000 kilometres from the transmitting antenna. Low frequency waves can also travel long distances by reflecting from the ionosphere, although this method. Reflection occurs at the ionospheric E layer or F layers, skywave signals can be detected at distances exceeding 300 kilometres from the transmitting antenna. 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, 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 market only after the output power of WWVB was increased in 1997 and 1999. Radio signals below 50 kHz are capable of penetrating ocean depths to approximately 200 metres, the longer the wavelength, 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. In the US, the Ground Wave Emergency Network or GWEN operated between 150 and 175 kHz, until replaced by satellite systems in 1999. GWEN was a land based military radio communications system which could survive, the 2007 World Radiocommunication Conference made this band a worldwide amateur radio allocation. An international 2.1 kHz allocation, the 2200 meter band, is available to amateur operators in several countries in Europe, New Zealand, Canada. The world record distance for a contact is over 10,000 km from near Vladivostok to New Zealand
3.
United States
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Forty-eight of the fifty states and the federal district are contiguous and located in North America between Canada and Mexico. The state of Alaska is in the northwest corner of North America, bordered by Canada to the east, the state of Hawaii is an archipelago in the mid-Pacific Ocean. The U. S. territories are scattered about the Pacific Ocean, the geography, climate and wildlife of the country are extremely diverse. At 3.8 million square miles and with over 324 million people, the United States is the worlds third- or fourth-largest country by area, third-largest by land area. It is one of the worlds most ethnically diverse and multicultural nations, paleo-Indians migrated from Asia to the North American mainland at least 15,000 years ago. European colonization began in the 16th century, the United States emerged from 13 British colonies along the East Coast. Numerous disputes between Great Britain and the following the Seven Years War led to the American Revolution. On July 4,1776, during the course of the American Revolutionary War, the war ended in 1783 with recognition of the independence of the United States by Great Britain, representing the first successful war of independence against a European power. The current constitution was adopted in 1788, after the Articles of Confederation, the first ten amendments, collectively named the Bill of Rights, were ratified in 1791 and designed to guarantee many fundamental civil liberties. During the second half of the 19th century, the American Civil War led to the end of slavery in the country. By the end of century, the United States extended into the Pacific Ocean. The Spanish–American War and World War I confirmed the status as a global military power. The end of the Cold War and the dissolution of the Soviet Union in 1991 left the United States as the sole superpower. The U. S. is a member of the United Nations, World Bank, International Monetary Fund, Organization of American States. The United States is a developed country, with the worlds largest economy by nominal GDP. It ranks highly in several measures of performance, including average wage, human development, per capita GDP. While the U. S. economy is considered post-industrial, characterized by the dominance of services and knowledge economy, the United States is a prominent political and cultural force internationally, and a leader in scientific research and technological innovations. In 1507, the German cartographer Martin Waldseemüller produced a map on which he named the lands of the Western Hemisphere America after the Italian explorer and cartographer Amerigo Vespucci
4.
Canada
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Canada is a country in the northern half of North America. Canadas border with the United States is the worlds longest binational land border, the majority of the country has a cold or severely cold winter climate, but southerly areas are warm in summer. Canada is sparsely populated, the majority of its territory being dominated by forest and tundra. It is highly urbanized with 82 per cent of the 35.15 million people concentrated in large and medium-sized cities, One third of the population lives in the three largest cities, Toronto, Montreal and Vancouver. Its capital is Ottawa, and other urban areas include Calgary, Edmonton, Quebec City, Winnipeg. Various aboriginal peoples had inhabited what is now Canada for thousands of years prior to European colonization. Pursuant to the British North America Act, on July 1,1867, the colonies of Canada, New Brunswick and this began an accretion of provinces and territories to the mostly self-governing Dominion to the present ten provinces and three territories forming modern Canada. With the Constitution Act 1982, Canada took over authority, removing the last remaining ties of legal dependence on the Parliament of the United Kingdom. Canada is a parliamentary democracy and a constitutional monarchy, with Queen Elizabeth II being the head of state. The country is officially bilingual at the federal level and it is one of the worlds most ethnically diverse and multicultural nations, the product of large-scale immigration from many other countries. Its advanced economy is the eleventh largest in the world, relying chiefly upon its abundant natural resources, Canadas long and complex relationship with the United States has had a significant impact on its economy and culture. Canada is a country and has the tenth highest nominal per capita income globally as well as the ninth highest ranking in the Human Development Index. It ranks among the highest in international measurements of government transparency, civil liberties, quality of life, economic freedom, Canada is an influential nation in the world, primarily due to its inclusive values, years of prosperity and stability, stable economy, and efficient military. While a variety of theories have been postulated for the origins of Canada. In 1535, indigenous inhabitants of the present-day Quebec City region used the word to direct French explorer Jacques Cartier to the village of Stadacona, from the 16th to the early 18th century Canada referred to the part of New France that lay along the St. Lawrence River. In 1791, the area became two British colonies called Upper Canada and Lower Canada collectively named The Canadas, until their union as the British Province of Canada in 1841. Upon Confederation in 1867, Canada was adopted as the name for the new country at the London Conference. The transition away from the use of Dominion was formally reflected in 1982 with the passage of the Canada Act, later that year, the name of national holiday was changed from Dominion Day to Canada Day
5.
Hertz
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The hertz is the unit of frequency in the International System of Units and is defined as one cycle per second. It is named for Heinrich Rudolf Hertz, the first person to provide proof of the existence of electromagnetic waves. Hertz are commonly expressed in SI multiples kilohertz, megahertz, gigahertz, kilo means thousand, mega meaning million, giga meaning billion and tera for trillion. Some of the units most common uses are in the description of waves and musical tones, particularly those used in radio-. It is also used to describe the speeds at which computers, the hertz is equivalent to cycles per second, i. e. 1/second or s −1. In English, hertz is also used as the plural form, as an SI unit, Hz can be prefixed, commonly used multiples are kHz, MHz, GHz and THz. One hertz simply means one cycle per second,100 Hz means one hundred cycles per second, and so on. The unit may be applied to any periodic event—for example, a clock might be said to tick at 1 Hz, the rate of aperiodic or stochastic events occur is expressed in reciprocal second or inverse second in general or, the specific case of radioactive decay, becquerels. Whereas 1 Hz is 1 cycle per second,1 Bq is 1 aperiodic radionuclide event per second, the conversion between a frequency f measured in hertz and an angular velocity ω measured in radians per second is ω =2 π f and f = ω2 π. This SI unit is named after Heinrich Hertz, as with every International System of Units unit named for a person, the first letter of its symbol is upper case. Note that degree Celsius conforms to this rule because the d is lowercase. — Based on The International System of Units, the hertz is named after the German physicist Heinrich Hertz, who made important scientific contributions to the study of electromagnetism. The name was established by the International Electrotechnical Commission in 1930, the term cycles per second was largely replaced by hertz by the 1970s. One hobby magazine, Electronics Illustrated, declared their intention to stick with the traditional kc. Mc. etc. units, sound is a traveling longitudinal wave which is an oscillation of pressure. Humans perceive frequency of waves as pitch. Each musical note corresponds to a frequency which can be measured in hertz. An infants ear is able to perceive frequencies ranging from 20 Hz to 20,000 Hz, the range of ultrasound, infrasound and other physical vibrations such as molecular and atomic vibrations extends from a few femtoHz into the terahertz range and beyond. Electromagnetic radiation is described by its frequency—the number of oscillations of the perpendicular electric and magnetic fields per second—expressed in hertz. Radio frequency radiation is measured in kilohertz, megahertz, or gigahertz
6.
Amateur radio
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The amateur radio service is established by the International Telecommunication Union through the International Telecommunication Regulations. National governments regulate technical and operational characteristics of transmissions and issue individual stations licenses with a call sign. Prospective amateur operators are tested for their understanding of key concepts in electronics, according to an estimate made in 2011 by the American Radio Relay League, two million people throughout the world are regularly involved with amateur radio. About 830,000 amateur radio stations are located in IARU Region 2 followed by IARU Region 3 with about 750,000 stations, a significantly smaller number, about 400,000, are located in IARU Region 1. The origins of amateur radio can be traced to the late 19th century, the First Annual Official Wireless Blue Book of the Wireless Association of America, produced in 1909, contains a list of amateur radio stations. This radio callbook lists wireless telegraph stations in Canada and the United States, as with radio in general, amateur radio was associated with various amateur experimenters and hobbyists. Amateur radio enthusiasts have significantly contributed to science, engineering, industry, research by amateur operators has founded new industries, built economies, empowered nations, and saved lives in times of emergency. Ham radio can also be used in the classroom to teach English, map skills, geography, math, science, the term ham radio was first a pejorative that mocked amateur radio operators with a 19th-century term for being bad at something, like ham-fisted or ham actor. It had already used for bad wired telegraph operators. Subsequently, the community adopted it as a moniker, much like the Know-Nothing Party, or other groups. Other, more entertaining explanations have grown up throughout the years, the many facets of amateur radio attract practitioners with a wide range of interests. Many amateurs begin with a fascination of radio communication and then combine other personal interests to make pursuit of the hobby rewarding, some of the focal areas amateurs pursue include radio contesting, radio propagation study, public service communication, technical experimentation, and computer networking. Amateur radio operators use various modes of transmission to communicate, the two most common modes for voice transmissions are frequency modulation and single sideband. FM offers high quality audio signals, while SSB is better at long distance communication when bandwidth is restricted. Radiotelegraphy using Morse code, also known as CW from continuous wave, is the extension of landline telegraphy developed by Samuel Morse. Morse, using internationally agreed message encodings such as the Q code, a similar legacy mode popular with home constructors is amplitude modulation, pursued by many vintage amateur radio enthusiasts and aficionados of vacuum tube technology. Demonstrating a proficiency in Morse code was for years a requirement to obtain an amateur license to transmit on frequencies below 30 MHz. Following changes in regulations in 2003, countries are no longer required to demand proficiency
7.
Amateur radio operator
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As a component of their license, amateur radio operators are assigned a call sign that they use to identify themselves during communication. There are about three million amateur radio operators worldwide, amateur radio operators are also known as radio amateurs or hams. The term ham as a nickname for radio operators originated in a pejorative usage by operators in commercial and professional radio communities. The word was adopted by amateur radio operators. Few governments maintain detailed demographic statistics of their radio operator populations. The majority of radio operators worldwide reside in Japan, the United States, Thailand, South Korea. The top five countries by percentage of the population are Japan, Slovenia, Taiwan, South Korea, only the governments of Yemen and North Korea currently prohibit their citizens from becoming amateur radio operators. In some countries, acquiring an amateur license is difficult because of the bureaucratic processes or fees that place access to a license out of reach for most citizens. Most nations permit foreign nationals to earn an amateur radio license, in the vast majority of countries, the population of amateur radio operators is predominantly male. In China 12% of amateur operators are women, whilst in the United States is it approximately 15%. The Young Ladies Radio League is an organization of female amateur radio operators. A male amateur radio operator can be referred to as an OM, a female amateur radio operator can be referred to as a YL, from the abbreviation used for young lady, regardless of the operators age. Sometimes the wife of a ham operator is called a YF, although these codes are derived from English language abbreviations, their use is common among amateur radio operators worldwide. Incidentally, the most common language heard in the HF amateur bands is English, in most countries there is no minimum age requirement to earn an amateur radio license and become an amateur radio operator. Although the number of radio operators in many countries increases from year to year. In some countries, the age is over 80 years old. The World Wide Young Contesters organization promotes youth involvement, particularly amongst Europeans, a strong tie also exists between the amateur radio community and the Scouting movement to introduce radio technology to youth. WOSMs annual Jamboree On The Air is Scoutings largest activity, with a half million Scouts, when referring to a person, the phrase Silent Key and its abbreviation SK indicates an amateur radio operator who is deceased
8.
Telegraphy
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Telegraphy is the long-distance transmission of textual or symbolic messages without the physical exchange of an object bearing the message. Thus semaphore is a method of telegraphy, whereas pigeon post is not, telegraphy requires that the method used for encoding the message be known to both sender and receiver. Such methods are designed according to the limits of the medium used. The use of signals, beacons, reflected light signals. In the 19th century, the harnessing of electricity led to the invention of electrical telegraphy, the advent of radio in the early 20th century brought about radiotelegraphy and other forms of wireless telegraphy. The word telegraph was first coined by the French inventor of the Semaphore line, Claude Chappe, a telegraph is a device for transmitting and receiving messages over long distances, i. e. for telegraphy. The word telegraph alone now generally refers to an electrical telegraph, Wireless telegraphy is also known as CW, for continuous wave, as opposed to the earlier radio technique of using a spark gap. Contrary to the definition used by Chappe, Morse argued that the term telegraph can strictly be applied only to systems that transmit. This is to be distinguished from semaphore, which transmits messages. Smoke signals, for instance, are to be considered semaphore, according to Morse, telegraph dates only from 1832 when Pavel Schilling invented one of the earliest electrical telegraphs. A telegraph message sent by a telegraph operator or telegrapher using Morse code was known as a telegram. A cablegram was a sent by a submarine telegraph cable. Later, a Telex was a sent by a Telex network. A wire picture or wire photo was a picture that was sent from a remote location by a facsimile telegraph. A diplomatic telegram, also known as a cable, is the term given to a confidential communication between a diplomatic mission and the foreign ministry of its parent country. These continue to be called telegrams or cables regardless of the used for transmission. Commercial electrical telegraphs were introduced from 1837, the first telegraphs came in the form of optical telegraph, including the use of smoke signals, beacons, or reflected light, which have existed since ancient times. Early proposals for a telegraph system were made to the Royal Society by Robert Hooke in 1684 and were first implemented on an experimental level by Sir Richard Lovell Edgeworth in 1767
9.
Amplitude modulation
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Amplitude modulation is a modulation technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. In amplitude modulation, the amplitude of the wave is varied in proportion to the waveform being transmitted. That waveform may, for instance, correspond to the sounds to be reproduced by a loudspeaker and this technique contrasts with frequency modulation, in which the frequency of the carrier signal is varied, and phase modulation, in which its phase is varied. AM was the earliest modulation method used to transmit voice by radio and it was developed during the first two decades of the 20th century beginning with Roberto Landell De Moura and Reginald Fessendens radiotelephone experiments in 1900. It remains in use today in many forms of communication, for example it is used in two way radios, VHF aircraft radio, Citizens Band Radio, and in computer modems. AM is often used to refer to mediumwave AM radio broadcasting, when it reaches its destination, the information signal is extracted from the modulated carrier by demodulation. In amplitude modulation, the amplitude or strength of the oscillations is what is varied. For example, in AM radio communication, a continuous wave signal has its amplitude modulated by an audio waveform before transmission. The audio waveform modifies the amplitude of the wave and determines the envelope of the waveform. In the frequency domain, amplitude modulation produces a signal with power concentrated at the carrier frequency, each sideband is equal in bandwidth to that of the modulating signal, and is a mirror image of the other. Standard AM is thus sometimes called double-sideband amplitude modulation to distinguish it more sophisticated modulation methods also based on AM. One disadvantage of all amplitude modulation techniques is that the receiver amplifies and detects noise, increasing the received signal to noise ratio, say, by a factor of 10, thus would require increasing the transmitter power by a factor of 10. For this reason AM broadcast is not favored for music and high fidelity broadcasting, another disadvantage of AM is that it is inefficient in power usage, at least two-thirds of the power is concentrated in the carrier signal. The carrier signal contains none of the information being transmitted. However its presence provides a means of demodulation using envelope detection, providing a frequency. The receiver may regenerate a copy of the frequency from a greatly reduced pilot carrier to use in the demodulation process. Even with the carrier totally eliminated in double-sideband suppressed-carrier transmission, carrier regeneration is possible using a Costas phase-locked loop and this doesnt work however for single-sideband suppressed-carrier transmission, leading to the characteristic Donald Duck sound from such receivers when slightly detuned. Single sideband is used widely in amateur radio and other voice communications both due to its power efficiency and bandwidth efficiency
10.
Single-sideband modulation
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Amplitude modulation produces an output signal that has twice the bandwidth of the original baseband signal. Single-sideband modulation avoids this bandwidth doubling, and the power wasted on a carrier, at the cost of increased device complexity, radio transmitters work by mixing a radio frequency signal of a specific frequency, the carrier wave, with the signal to be broadcast. That is, the signal has a spectrum with twice the bandwidth of the original input signal. In conventional AM radio, this signal is sent to the radio frequency amplifier. Due to the nature of the process, the quality of the resulting signal can be defined by the difference between the maximum and minimum signal energy. Normally the maximum signal energy will be the carrier itself, perhaps twice as powerful as the mixed signals, SSB takes advantage of the fact that the entire original signal is encoded in either one of these sidebands. It is not necessary to broadcast the entire mixed signal, a receiver can extract the entire signal from either the upper or lower sideband. This means that the amplifier can be used more efficiently. A transmitter can choose to only the upper or lower sideband. By doing so, the amplifier only has to work effectively on one half the bandwidth, as a result, SSB transmissions use the available amplifier energy more efficiently, providing longer-range transmission with little or no additional cost. The first U. S. patent for SSB modulation was applied for on December 1,1915 by John Renshaw Carson, the U. S. Navy experimented with SSB over its radio circuits before World War I. SSB first entered service on January 7,1927 on the longwave transatlantic public radiotelephone circuit between New York and London. The high power SSB transmitters were located at Rocky Point, New York and Rugby, the receivers were in very quiet locations in Houlton, Maine and Cupar Scotland. SSB was also used over long distance lines, as part of a technique known as frequency-division multiplexing. FDM was pioneered by telephone companies in the 1930s and this enabled many voice channels to be sent down a single physical circuit, for example in L-carrier. SSB allowed channels to be spaced just 4,000 Hz apart, amateur radio operators began serious experimentation with SSB after World War II. The Strategic Air Command established SSB as the standard for its aircraft in 1957. It has become a de facto standard for voice radio transmissions since then
11.
United Kingdom
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The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom or Britain, is a sovereign country in western Europe. Lying off the north-western coast of the European mainland, the United Kingdom includes the island of Great Britain, Northern Ireland is the only part of the United Kingdom that shares a land border with another sovereign state—the Republic of Ireland. The Irish Sea lies between Great Britain and Ireland, with an area of 242,500 square kilometres, the United Kingdom is the 78th-largest sovereign state in the world and the 11th-largest in Europe. It is also the 21st-most populous country, with an estimated 65.1 million inhabitants, together, this makes it the fourth-most densely populated country in the European Union. The United Kingdom is a monarchy with a parliamentary system of governance. The monarch is Queen Elizabeth II, who has reigned since 6 February 1952, other major urban areas in the United Kingdom include the regions of Birmingham, Leeds, Glasgow, Liverpool and Manchester. The United Kingdom consists of four countries—England, Scotland, Wales, the last three have devolved administrations, each with varying powers, based in their capitals, Edinburgh, Cardiff and Belfast, respectively. The relationships among the countries of the UK have changed over time, Wales was annexed by the Kingdom of England under the Laws in Wales Acts 1535 and 1542. A treaty between England and Scotland resulted in 1707 in a unified Kingdom of Great Britain, which merged in 1801 with the Kingdom of Ireland to form the United Kingdom of Great Britain and Ireland. Five-sixths of Ireland seceded from the UK in 1922, leaving the present formulation of the United Kingdom of Great Britain, there are fourteen British Overseas Territories. These are the remnants of the British Empire which, at its height in the 1920s, British influence can be observed in the language, culture and legal systems of many of its former colonies. The United Kingdom is a country and has the worlds fifth-largest economy by nominal GDP. The UK is considered to have an economy and is categorised as very high in the Human Development Index. It was the worlds first industrialised country and the worlds foremost power during the 19th, the UK remains a great power with considerable economic, cultural, military, scientific and political influence internationally. It is a nuclear weapons state and its military expenditure ranks fourth or fifth in the world. The UK has been a permanent member of the United Nations Security Council since its first session in 1946 and it has been a leading member state of the EU and its predecessor, the European Economic Community, since 1973. However, on 23 June 2016, a referendum on the UKs membership of the EU resulted in a decision to leave. The Acts of Union 1800 united the Kingdom of Great Britain, Scotland, Wales and Northern Ireland have devolved self-government
12.
International Telecommunication Union
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ITU, based in Geneva, Switzerland, is a member of the United Nations Development Group. ITU has been an intergovernmental public-private partnership organization since its inception, ITU was formed in 1865, in Paris, at the International Telegraph Convention, this makes it one of the oldest intergovernmental organizations in the world. ITU became a United Nations specialized agency in 1947, the ITU comprises three sectors, each managing a different aspect of the matters handled by the Union, as well as ITU Telecom. The sectors were created during the restructuring of ITU at its 1992 Plenipotentiary Conference, radiocommunication Established in 1927 as the International Radio Consultative Committee or CCIR, this sector manages the international radio-frequency spectrum and satellite orbit resources. In 1992, the CCIR became the ITU-R, Standardization Standardization was the original purpose of ITU since its inception. Established in 1956 as the International Telephone and Telegraph Consultative Committee or CCITT, in 1993, the CCITT became the ITU-T. Development Established in 1992, this sector helps spread equitable, sustainable and affordable access to information and communication technologies, ITU Telecom ITU Telecom organizes major events for the worlds ICT community. A permanent General Secretariat, headed by the Secretary General, manages the work of the Union. The basic texts of the ITU are adopted by the ITU Plenipotentiary Conference, the ITU is headed by a Secretary-General, who is elected to a four-year term by the member states at the ITU Plenipotentiary Conference. On 23 October 2014 Houlin Zhao was elected 19th Secretary-General of the ITU at the Plenipotentiary Conference in Busan and his four-year mandate started on 1 January 2015, and he was formally inaugurated on 15 January 2015. There are 193 Member States of the ITU, which are all UN member states, the most recent member state to join the ITU is South Sudan, which became a member on 14 July 2011. The Republic of China was blocked from membership by the Peoples Republic of China, palestine was admitted as an observer in 2010. The Summit was held as two conferences in 2003 and 2005 in Geneva and Tunis, respectively, with the aim of bridging the digital divide, in December 2012, the ITU facilitated The World Conference on International Telecommunications 2012 in Dubai. WCIT-12 was a conference to address International Telecommunications Regulations, the international rules for telecommunications. The previous conference to update the Regulations was held in Melbourne in 1988, in August 2012, ITU called for a public consultation on a draft document ahead of the conference. 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 to manage key resources such as Internet addresses and Domain Names. Some outside the United States believe that the United States exerts too much influence over the governance of the Internet, current proposals look to take into account the prevalence of data communications
13.
Geneva
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Geneva is the second most populous city in Switzerland and is the most populous city of Romandy, the French-speaking part of Switzerland. Situated where the Rhône exits Lake Geneva, it is the capital of the Republic, the municipality has a population of 198,072, and the canton has 484,736 residents. In 2014, the compact agglomération du Grand Genève had 946,000 inhabitants in 212 communities in both Switzerland and France, within Swiss territory, the commuter area named Métropole lémanique contains a population of 1.25 million. This area is essentially spread east from Geneva towards the Riviera area and north-east towards Yverdon-les-Bains, Geneva is the city that hosts the highest number of international organizations in the world. It is also the place where the Geneva Conventions were signed, Geneva was ranked as the worlds ninth most important financial centre for competitiveness by the Global Financial Centres Index, ahead of Frankfurt, and third in Europe behind London and Zürich. A2009 survey by Mercer found that Geneva has the third-highest quality of life of any city in the world, the city has been referred to as the worlds most compact metropolis and the Peace Capital. In 2009 and 2011, Geneva was ranked as, respectively, the city was mentioned in Latin texts, by Caesar, with the spelling Genava, probably from a Celtic toponym *genawa- from the stem *genu-, in the sense of a bending river or estuary. The medieval county of Geneva in Middle Latin was known as pagus major Genevensis or Comitatus Genevensis, the name takes various forms in modern languages, Geneva /dʒᵻˈniːvə/ in English, French, Genève, German, Genf, Italian, Ginevra, and Romansh, Genevra. The city in origin shares its name, *genawa estuary, with the Italian port city of Genoa, Geneva was an Allobrogian border town, fortified against the Helvetii tribe, when the Romans took it in 121 BC. It became Christian under the Late Roman Empire, and acquired its first bishop in the 5th century, having been connected to the bishopric of Vienne in the 4th. In the Middle Ages, Geneva was ruled by a count under the Holy Roman Empire until the late 14th century, around this time the House of Savoy came to dominate the city. In the 15th century, a republican government emerged with the creation of the Grand Council. In 1541, with Protestantism in the ascendancy, John Calvin, by the 18th century, however, Geneva had come under the influence of Catholic France, which cultivated the city as its own. France also tended to be at odds with the ordinary townsfolk, in 1798, revolutionary France under the Directory annexed Geneva. At the end of the Napoleonic Wars, on 1 June 1814, in 1907, the separation of Church and State was adopted. Geneva flourished in the 19th and 20th centuries, becoming the seat of international organizations. Geneva is located at 46°12 North, 6°09 East, at the end of Lake Geneva. It is surrounded by two chains, the Alps and the Jura
14.
Medium wave
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Medium wave is the part of the medium frequency radio band used mainly for AM radio broadcasting. Practical groundwave reception typically extends to 200–300 miles, with distances over terrain with higher ground conductivity. Most broadcast stations use groundwave to cover their listening area, Medium waves can also reflect off charged particle layers in the ionosphere and return to Earth at much greater distances, this is called the skywave. At night, especially in winter months and at times of low solar activity, when this happens, MF radio waves can easily be received many hundreds or even thousands of miles away as the signal will be reflected by the higher F layer. This can allow very long-distance broadcasting, but can also interfere with distant local stations, due to 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, the signals of distant station may interfere with the signals of local stations on the same frequency. These channels are called clear channels, and they are required to broadcast at higher powers of 10 to 50 kW and this arrangement had numerous practical difficulties. The Commerce Department rarely intervened in such cases but left it up to stations to enter into voluntary timesharing agreements amongst themselves, the addition of a third entertainment wavelength,400 meters, did little to solve this overcrowding. In 1923, the Commerce Department realized that as more and more stations were applying for commercial licenses, on 15 May 1923, Commerce Secretary Herbert Hoover announced a new bandplan which set aside 81 frequencies, in 10 kHz steps, from 550 kHz to 1350 kHz. Each station would be assigned one frequency, no longer having to broadcast weather, class A and B stations were segregated into sub-bands. Today in most of the Americas, mediumwave broadcast stations are separated by 10 kHz and have two sidebands of up to ±5 kHz in theory, in the rest of the world, the separation is 9 kHz, with sidebands of ±4.5 kHz. Both provide adequate quality for voice, but are insufficient for high-fidelity broadcasting. In the US and Canada the maximum power is restricted to 50 kilowatts. Those stations which shut down completely at night are known as daytimers. In most cases there are two limits, a lower one for omnidirectional and a higher one for directional radiation with minima in certain directions. The power limit can also be depending on daytime and it is possible, other countries may only operate low-powered transmitters on the same frequency, again subject to agreement. For example, Russia operates a transmitter, located in its Kaliningrad exclave and used for external broadcasting. Due to the demand for frequencies in Europe, many countries operate single frequency networks, in Britain
15.
Effective radiated power
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Effective radiated power, synonymous with equivalent radiated power, is an IEEE standardized definition of directional radio frequency power transmitted from a theoretical half-wave dipole antenna. It is differentiated from effective isotropic radiated power mainly by use of antenna gain instead of absolute gain in the calculation. The term antenna gain is assumed to be absolute unless specifically stated to be relative, the gain is then multiplied by the power actually accepted by the antenna to result in the actual ERP value. Power losses which occur prior to the antenna, e. g. in the line or from inefficiency in the generator itself are therefore not included in the calculation of ERP or EIRP. Antenna gain is closely related to directivity and often used interchangeably. However, gain is less than directivity by a factor called radiation efficiency. Whereas directivity is entirely a function of wavelength and the geometry and type of antenna, specifically, accelerating charge causes electromagnetic radiation per Maxwells equations. Therefore, antennas use a current distribution on radiating elements to generate electromagnetic energy that propagates away from the antenna and this coupling is never 100% efficient, and therefore antenna gain will always be less than directivity by this efficiency factor. The receiver would not be able to determine a difference, maximum directivity of an ideal half-wave dipole is a constant, i. e.0 dBd =2.15 dBi. Therefore, ERP is always 2.15 dB less than EIRP, the ideal dipole antenna could be further replaced by an isotropic radiator, and the receiver cannot know the difference so long as the input power is increased by 2.15 dB. Unfortunately, the distinction between dBd and dBi is often left unstated and the reader is forced to infer which was used. For example, a Yagi-Uda antenna is constructed from several dipoles arranged at intervals to create better energy focusing than a simple dipole. Since it is constructed from dipoles, often its antenna gain is expressed in dBd, obviously this ambiguity is undesirable with respect to engineering specifications. A Yagi-Uda antennas maximum directivity is 8.77 dBd =10.92 dBi and its gain necessarily must be less than this by the factor η, which must be negative in units of dB. Neither ERP nor EIRP can be calculated without knowledge of the power accepted by the antenna, let us assume a 100 Watt transmitter with losses of 6 dB prior to the antenna. ERP <22. 77dBW and EIRP <24. 92dBW, polarization has not been taken into account so far, but properly it must be. When considering the dipole radiator previously we assumed that it was aligned with the receiver. Now assume, however, that the antenna is circularly polarized
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AM broadcasting
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AM broadcasting is the process of radio broadcasting using amplitude modulation. AM was the first method of impressing sound on a signal and is still widely used today. Commercial and public AM broadcasting is authorized in the wave band worldwide. Commercial AM broadcasting developed from amateur broadcasts around 1920, and was the commercially important form of radio broadcasting until FM broadcasting began after World War II. This period is known as the Golden Age of Radio, today, AM competes with FM, as well as with various digital radio broadcasting services distributed from terrestrial and satellite transmitters. AM broadcasting was the first broadcasting technology invented, the technology of amplitude modulation radio transmission was developed between 1900 and 1920. This was used for private communication and message traffic, such as telegrams. The entrepreneurs who developed AM radiotelephone transmission did not anticipate broadcasting voice, the term broadcasting, borrowed from agriculture, was applied to this new activity around 1920. Prior to 1920 there was no concept of broadcasting, or that radio listeners could be a market for entertainment. Although there were a number of broadcasts during this period. True radio broadcasting didnt begin until around 1920, when it sprang up spontaneously among amateur stations, AM remained the dominant method of broadcasting for the next 30 years, a period called the Golden Age of Radio, until FM broadcasting started to become widespread in the 1950s. AM remains a popular, profitable entertainment medium today and the dominant form of broadcasting in some such as Australia. The first AM voice transmission was made by Canadian researcher Reginald Fessenden on 23 December 1900, Fessenden is a significant figure in the development of AM radio. He helped develop one of the first – the Alexanderson alternator, the first practical continuous wave AM transmitters were based on versions of the Poulsen arc transmitter invented in 1903, and the huge, expensive Alexanderson alternator, developed 1906–1910. The modifications necessary to transmit AM were clumsy and resulted in low audio quality. Modulation was usually accomplished by a carbon microphone inserted directly in the antenna wire, the limited power handling ability of the microphone severely limited the power of the first radiotelephones, in powerful transmitters water-cooled microphones had to be used. At the receiving end, the crystal radio receivers then in use could not drive loudspeakers, only earphones. The discovery in 1912 of the ability of the Audion vacuum tube, invented in 1906 by Lee De Forest
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Radio-frequency identification
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Radio-frequency identification uses electromagnetic fields to automatically identify and track tags attached to objects. The tags contain electronically stored information, Passive tags collect energy from a nearby RFID readers interrogating radio waves. Active tags have a power source such as a battery. Unlike a barcode, the tag need not be within the line of sight of the reader, RFID is one method for Automatic Identification and Data Capture. These concerns resulted in standard specifications development addressing privacy and security issues, ISO/IEC18000 and ISO/IEC29167 use on-chip cryptography methods for untraceability, tag and reader authentication, and over-the-air privacy. ISO/IEC20248 specifies a digital data structure for RFID and barcodes providing data, source. This work is done within ISO/IEC JTC 1/SC31 Automatic identification, in 2014, the world RFID market is worth US$8.89 billion, up from US$7.77 billion in 2013 and US$6.96 billion in 2012. This includes tags, readers, and software/services for RFID cards, labels, fobs, the market value is expected to rise to US$18.68 billion by 2026. In 1945, Léon Theremin invented a tool for the Soviet Union which retransmitted incident radio waves with the audio information. Sound waves vibrated a diaphragm which slightly altered the shape of the resonator, similar technology, such as the IFF transponder, was routinely used by the allies and Germany in World War II to identify aircraft as friend or foe. Transponders are still used by most powered aircraft to this day, another early work exploring RFID is the landmark 1948 paper by Harry Stockman. Considerable research and development work has to be done before the basic problems in reflected-power communication are solved. Mario Cardullos device, patented on January 23,1973, was the first true ancestor of modern RFID, the basic Cardullo patent covers the use of RF, sound and light as transmission media. The original business plan presented to investors in 1969 showed uses in transportation, banking, security and medical. An early demonstration of reflected power RFID tags, both passive and semi-passive, was performed by Steven Depp, Alfred Koelle, and Robert Frayman at the Los Alamos National Laboratory in 1973, the portable system operated at 915 MHz and used 12-bit tags. This technique is used by the majority of todays UHFID and microwave RFID tags, the first patent to be associated with the abbreviation RFID was granted to Charles Walton in 1983. A radio-frequency identification system uses tags, or labels attached to the objects to be identified, two-way radio transmitter-receivers called interrogators or readers send a signal to the tag and read its response. RFID tags can be passive, active or battery-assisted passive
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630-meter band
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It was formally allocated to amateurs at the 2012 World Radiocommunication Conference. The new WRC-12 allocation did not take effect until 1 January 2013. However, several countries previously allocated the WRC-12 band to amateurs domestically, previously, several other countries have authorized temporary allocations or experimental operations on nearby frequencies. The band is in the Medium Frequency region, within the greater 415–526.5 kHz maritime band, with maritime traffic largely displaced from 500 kHz band, some countries had taken steps prior to 2012 to allocate frequencies at or near 500 kHz to amateur radio use. During the 2012 World Radiocommunication Conference of the International Telecommunication Union, the frequencies studied were between 415 kHz and 526.5 kHz. The result was that 472–479 kHz was identified as agreeable for all three ITU Regions, except for countries such as Russia, China and Arab states. WRC-12 re-allocated the original 500 kHz frequency back to exclusive maritime mobile use for new navigation systems, following that, individual regulatory authorities need to implement the change nationally in order to make the allocation available to radio amateurs under their jurisdiction. Recently amateurs have experimented with radio communication near 474.2 kHz. Germany allocated the frequencies to amateur radio based on the WRC-12 conference, the Principality of Monaco allocated 472–479 kHz to the amateur service on 18 May 2012. The Philippines allocated 472–479 kHz to amateur radio, with a date of 30 August 2012. In New Zealand, the band 472 kHz to 479 kHz was allocated to radio, on a secondary basis. Amateur transmissions are limited to 25 watts EIRP, in Australia amateurs now have an allocation from 472 to 479 kHz, known as the 630 metre band. The maximum EIRP is 5 Watts, in Belgium, on 14 August 2013, a new allocation of 472 to 479 kHz has been added to the existing allocation of 501 to 504 kHz for ham-radio operators holding a HAREC-class license. The maximum EIRP is 5 Watts, in France amateurs have access to 472–479 kHz, with 1 Watt EIRP. In Norway, including Svalbard, Jan Mayen, and the Bouvet Island, maximum output power is 100 watts, and maximum EIRP of 1 Watt. In Poland, amateurs have an allocation from 472 to 479 kHz since 18 February 2014, the maximum EIRP is 1 Watt. In Canada, amateurs have an allocation from 472 to 479 kHz beginning 1 April 2014. In the United States of America, the Federal Communications Commission has approved 472 to 479 MHz on a basis to the amateur service in a report
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American Radio Relay League
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The American Radio Relay League is the largest membership association of amateur radio enthusiasts in the USA. ARRL is an organization, and was co-founded on April 6,1914 by Hiram Percy Maxim and Clarence D. Tuska of Hartford. The ARRL has approximately 154,000 members, in addition to members in the US, the organization claims over 7,000 members in other countries. The ARRL publishes many books and a membership journal called QST. The ARRL held its Centennial Convention in Hartford, Connecticut in July 2014, the ARRL is the primary representative organization of amateur radio operators to the US government. It performs this function by lobbying the US Congress and the Federal Communications Commission, the organization is governed by a member-elected, volunteer Board of Directors. Each director serves a term and represents the members within their particular region of the country. The national headquarters facilities are located in Newington, Connecticut, along with the administrative headquarters, the 7-acre site is home to amateur radio station W1AW. The ARRL Field Organization carries out local and regional activities across the United States, the ARRL is governed by a member-elected, volunteer Board of Directors. The organization divides its membership into 15 Divisions, each representing a portion of the country. One Director and one Vice-Director are elected by the members of each Division to serve a three-year term, Director elections are staggered so that approximately one-third of the Directors and Vice Directors are up for election each year. The Board of Directors manages policy direction for the organization as a whole, the Board of Directors appoints an Executive Committee, led by the President and consisting of members of the ARRL Board of Directors, to make policy decisions between full Board meetings. ARRLs officers manage day-to-day administrative operation of the organization, led by the Chief Executive Officer and these paid officers hold their positions as long as the Board of Directors approve but have no vote on the Board. Local and regional operational activities of the American Radio Relay League are carried out through its Field Organization, the organization divides the 15 Divisions into 71 separate geographic regions called Sections. Each Section has a team of one elected, volunteer Section Manager. Section Managers are elected by the living within the section for a two-year term. The Section Manager appoints a team of volunteers, a Section Manager may optionally appoint one or more Assistant Section Managers. An important function of the ARRL Field Organization is organizing emergency communications in the event of civil or natural disaster, the ARRLs Amateur Radio Emergency Services program is organized through the ARRL Field Organization
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International Standard Book Number
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The International Standard Book Number is a unique numeric commercial book identifier. An ISBN is assigned to each edition and variation of a book, for example, an e-book, a paperback and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, the method of assigning an ISBN is nation-based and varies from country to country, often depending on how large the publishing industry is within a country. The initial ISBN configuration of recognition was generated in 1967 based upon the 9-digit Standard Book Numbering created in 1966, the 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108. Occasionally, a book may appear without a printed ISBN if it is printed privately or the author does not follow the usual ISBN procedure, however, this can be rectified later. Another identifier, the International Standard Serial Number, identifies periodical publications such as magazines, the ISBN configuration of recognition was generated in 1967 in the United Kingdom by David Whitaker and in 1968 in the US by Emery Koltay. The 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108, the United Kingdom continued to use the 9-digit SBN code until 1974. The ISO on-line facility only refers back to 1978, an SBN may be converted to an ISBN by prefixing the digit 0. For example, the edition of Mr. J. G. Reeder Returns, published by Hodder in 1965, has SBN340013818 -340 indicating the publisher,01381 their serial number. This can be converted to ISBN 0-340-01381-8, the check digit does not need to be re-calculated, since 1 January 2007, ISBNs have contained 13 digits, a format that is compatible with Bookland European Article Number EAN-13s. An ISBN is assigned to each edition and variation of a book, for example, an ebook, a paperback, and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, a 13-digit ISBN can be separated into its parts, and when this is done it is customary to separate the parts with hyphens or spaces. Separating the parts of a 10-digit ISBN is also done with either hyphens or spaces, figuring out how to correctly separate a given ISBN number is complicated, because most of the parts do not use a fixed number of digits. ISBN issuance is country-specific, in that ISBNs are issued by the ISBN registration agency that is responsible for country or territory regardless of the publication language. Some ISBN registration agencies are based in national libraries or within ministries of culture, in other cases, the ISBN registration service is provided by organisations such as bibliographic data providers that are not government funded. In Canada, ISBNs are issued at no cost with the purpose of encouraging Canadian culture. In the United Kingdom, United States, and some countries, where the service is provided by non-government-funded organisations. Australia, ISBNs are issued by the library services agency Thorpe-Bowker
