1.
Cumbria
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Cumbria is a non-metropolitan county in North West England. The county and Cumbria County Council, its government, came into existence in 1974 after the passage of the Local Government Act 1972. Cumbrias county town is Carlisle, in the north of the county, the county of Cumbria consists of six districts, and in 2008 had a population of just under half a million. Cumbria is one of the most sparsely populated counties in the United Kingdom, a large area of the south east of the county is within the Yorkshire Dales National Park while the east of the county fringes the North Pennines AONB. Much of Cumbria is mountainous, and it contains every peak in England over 3,000 feet above sea level, with Scafell Pike at 3,209 feet being the highest point of England. An upland, coastal, and rural area, Cumbrias history is characterised by invasions, migration, notable historic sites in Cumbria include Carlisle Castle, Furness Abbey, Hardknott Roman Fort, Brough Castle and Hadrians Wall, a UNESCO World Heritage Site. D. Based on inscriptional evidence from the area, the Roman civitas of the Carvetii seems to have covered portions of Cumbria, the names Cumbria, Cymru, Cambria, and Cumberland are derived from the name these people gave themselves, *kombroges in Common Brittonic, which originally meant compatriots. In the Early Middle Ages, Cumberland formed the core of the Brittonic kingdom of Rheged, for the rest of the first millennium, Cumbria was contested by several entities who warred over the area, including the Brythonic Kingdom of Strathclyde and the Anglian kingdom of Northumbria. Most of modern-day Cumbria was a principality in the Kingdom of Scotland at the time of the Norman conquest of England in 1066, in 1092 Cumberland was invaded by William II and incorporated into England. There were at least three sieges of Carlisle fought between England and Scotland, and two sieges during the Jacobite risings. In particular, the west-coast towns of Workington, Millom and Barrow-in-Furness saw large iron and steel mills develop, Kendal, Keswick and Carlisle all became mill towns, with textiles, pencils and biscuits among the products manufactured in the region. Later, the childrens writer Beatrix Potter also wrote in the region and became a major landowner and its strategic authority is Cumbria County Council. Local papers The Westmorland Gazette and Cumberland and Westmorland Herald continue to use the name of their historic county, other publications, such as local government promotional material, describe the area as Cumbria, as do the Lake District National Park Authority and most visitors. Cumbria is the most northwesterly county of England, the northernmost and southernmost points in Cumbria are just west of Deadwater, Northumberland and South Walney respectively. Kirkby Stephen and St Bees Head are the most easterly and westerly points of the county, at 978 metres Scafell Pike is the highest point in Cumbria and in England. Windermere is the largest natural lake in England, the Lancaster Canal runs from Preston into South Cumbria and is partly in use. The Ulverston Canal which once reached to Morecambe Bay is maintained although it was closed in 1945, the Solway Coast and Arnside and Silverdale AONBs lie in the lowland areas of the county, to the north and south respectively. Cumbria is bordered by the English counties of Northumberland, County Durham, North Yorkshire, Lancashire, the boundaries are along the Irish Sea to Morecambe Bay in the west, and along the Pennines to the east
2.
Atomic clock
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The principle of operation of an atomic clock is not based on nuclear physics, but rather on atomic physics, it uses the microwave signal that electrons in atoms emit when they change energy levels. Early atomic clocks were based on masers at room temperature, currently, the most accurate atomic clocks first cool the atoms to near absolute zero temperature by slowing them with lasers and probing them in atomic fountains in a microwave-filled cavity. An example of this is the NIST-F1 atomic clock, one of the primary time. The accuracy of an atomic clock depends on two factors, the first factor is temperature of the sample atoms—colder atoms move much more slowly, allowing longer probe times. The second factor is the frequency and intrinsic width of the electronic transition, higher frequencies and narrow lines increase the precision. National standards agencies in many countries maintain a network of atomic clocks which are intercompared and these clocks collectively define a continuous and stable time scale, International Atomic Time. For civil time, another time scale is disseminated, Coordinated Universal Time, UTC is derived from TAI, but approximately synchronised, by using leap seconds, to UT1, which is based on actual rotation of the Earth with respect to the solar time. The idea of using atomic transitions to measure time was suggested by Lord Kelvin in 1879, magnetic resonance, developed in the 1930s by Isidor Rabi, became the practical method for doing this. In 1945, Rabi first publicly suggested that atomic beam magnetic resonance might be used as the basis of a clock, the first atomic clock was an ammonia maser device built in 1949 at the U. S. National Bureau of Standards. It was less accurate than existing quartz clocks, but served to demonstrate the concept, calibration of the caesium standard atomic clock was carried out by the use of the astronomical time scale ephemeris time. This led to the agreed definition of the latest SI second being based on atomic time. Equality of the ET second with the SI second has been verified to within 1 part in 1010, the SI second thus inherits the effect of decisions by the original designers of the ephemeris time scale, determining the length of the ET second. Since the beginning of development in the 1950s, atomic clocks have been based on the transitions in hydrogen-1, caesium-133. The first commercial atomic clock was the Atomichron, manufactured by the National Company, more than 50 were sold between 1956 and 1960. This bulky and expensive instrument was replaced by much smaller rack-mountable devices, such as the Hewlett-Packard model 5060 caesium frequency standard. In August 2004, NIST scientists demonstrated a chip-scale atomic clock, according to the researchers, the clock was believed to be one-hundredth the size of any other. It requires no more than 125 mW, making it suitable for battery-driven applications and this technology became available commercially in 2011. Ion trap experimental optical clocks are more precise than the current caesium standard, in March 2017, NASA plans to deploy the Deep Space Atomic Clock, a miniaturized, ultra-precise mercury-ion atomic clock, into outer space
3.
Time standard
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A time standard is a specification for measuring time, either the rate at which time passes, or points in time, or both. In modern times, several time specifications have been recognized as standards. An example of a kind of time standard can be a time scale, a standard for civil time can specify both time intervals and time-of-day. Standardized time measurements are made using a clock to count periods of some cyclic change, historically, time standards were often based on the Earths rotational period. From the late 17th century to the 19th century it was assumed that the Earths daily rotational rate was constant. Time standards based on Earth rotation were replaced for use from 1952 onwards by an ephemeris time standard based on the Earths orbital period. Various types of second and day are used as the time interval for most time scales. Other intervals of time are usually defined in terms of these two, apparent solar time is based on the solar day, which is the period between one solar noon and the next. A solar day is approximately 24 hours of mean time, as the variation accumulates over a few weeks, there are differences as large as 16 minutes between apparent solar time and mean solar time. However, these cancel out over a year. There are also other perturbations such as Earths wobble, but these are less than a second per year, sidereal time is time by the stars. A sidereal rotation is the time it takes the Earth to make one revolution with respect to the stars and it is well known that observations of the Sun pose substantial obstacles to the achievement of accuracy in measurement. Mean solar time was originally apparent solar time corrected by the equation of time, Greenwich Mean Time was originally mean time deduced from meridian observations made at the Royal Greenwich Observatory. The principal meridian of that observatory was chosen in 1884 by the International Meridian Conference to be the Prime Meridian. GMT either by name or as mean time at Greenwich used to be an international time standard. The more current refined version of UT, UT1, is still in reality mean time at Greenwich, Greenwich Mean Time is still the legal time in the UK. But Coordinated Universal Time is in actual use in the UK. Universal Time is mean solar time at 0° longitude, some implementations are UT0 is the time of a particular place of observation
4.
National Physical Laboratory (United Kingdom)
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The National Physical Laboratory is the national measurement standards laboratory for the United Kingdom, based at Bushy Park in Teddington, London, England. It is the largest applied physics organisation in the UK, NPL is an internationally respected centre of excellence in measurement and materials science. Since 1900, when Bushy House was selected as the site of NPL, today it provides the scientific resources for the National Measurement System financed by the Department for Business, Innovation and Skills. NPL also offers a range of services, applying scientific skills to industrial measurement problems. The NPL cooperates with professional networks such as those of the IET to support scientists, NPL is at the forefront of new developments in metrology, such as researching metrology for, and standardizing, nanotechnology. NPL is mainly based on the Teddington site but also has a site in Huddersfield for dimensional metrology, Teddington was also home to the UK National Chemical Laboratory but this was closed in 1965 and some of its work was transferred to NPL. The laboratory was run by the UK government, with members of staff being part of the civil service. Administration of the NPL was contracted out in 1995 under a GOCO model, with Serco winning the bid, under this regime, overhead costs halved, third party revenues grew by 16% per annum, and the number of peer-reviewed research papers published doubled. It was decided in 2012 to change the model for NPL from 2014 onward to include academic partners. The date of the changeover was postponed for up to a year. The laboratory transferred back to Department for Business, Innovation and Skills ownership on 1 January 2015, NPL was initially sited entirely within Bushy House but grew to fill a large selection of buildings on the Teddington site. Many of these buildings were demolished and the moved to a large state-of-the-art laboratory for NPL that was built between 1998 and 2007. In January 2013 funding for a new £25m Advanced Metrology Laboratory was announced that will be built on the footprint of an unused building. H. J. Gough one of the pioneers of research into metal fatigue worked at NPL for 19 years from 1914-38, the inventor Sir Barnes Wallis did early development work there on the Bouncing Bomb used in the Dam Busters wartime raids. Sydney Goldstein and Sir James Lighthill worked in NPLs aerodynamics division during World War II researching boundary layer theory, dr Clifford Hodge also worked there and was engaged in research on semiconductors
5.
Teddington
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Teddington is a town in the London Borough of Richmond upon Thames. Until 1965, it was in the county of Middlesex. Teddington is on the bank of the Thames, just after the start of a long meander. Teddingtons centre is mid-rise urban development, Teddington is bisected by an almost continuous road of shops, offices and other facilities running from the river to Bushy Park. There are two clusters of offices on this route, on the edge of Bushy Park the NPL, NMO, around Teddington Station and the town centre are a number of offices in industries such as direct marketing and IT, which include Tearfund and BMT Limited. Several riverside businesses and houses were redeveloped in the last quarter of the 20th century as blocks of riverside flats, as of 2016 the riverside side of the former Teddington Studios is being developed to provide modern apartment blocks and other smaller houses. The first/last lock on the Thames, Teddington Lock, which is just within Hams boundary, is accessible via the Teddington Lock Footbridges, in 2001 the RNLI opened the Teddington Lifeboat Station, one of the four Thames lifeboat stations, below the lock on the Teddington side. The station became operational in January 2002 and is the only station on the river. The name Teddington comes from the name of an Old English tribal leader, the place was known in Saxon and Norman times as Todyngton and Tutington. There have been isolated findings of flint and bone tools from the Mesolithic and Neolithic periods in Bushy Park, however, the first permanent settlement in Teddington was probably in Saxon times. Teddington was not mentioned in Domesday Book as it was included under the Hampton entry, Teddington Manor was first owned by Benedictine monks in Staines and it is believed they built a chapel dedicated to St. Mary on the same site as todays St. Marys Church. In 971, a charter gave the land in Teddington to the Abbey of Westminster, in 1540 some common land of Teddington was enclosed to form Bushy Park and acted as more hunting grounds. Bushy House was built in 1663, and its residents included British Prime Minister Lord North who lived there for over twenty years. A large minority of the lay in largely communal open fields. These were inclosed in two phases, in 1800 and 1818, the facilities were later converted into the National Physical Laboratory. In subsequent centuries, Teddington enjoyed a life due to the proximity of royalty. But the Little Ice Age had made farming much less profitable and this change resulted in great economic change in the 19th century. The first major event was the construction of Teddington Lock in 1811 with its weir across the river and this was the first of five locks built at the time by the City of London Corporation
6.
Babcock International
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Although the company has civil contracts, its main business is with public bodies, particularly the UK Ministry of Defence and Network Rail. The company has four operating divisions with overseas operations based in Africa, Babcock is listed on the London Stock Exchange and is a constituent of the FTSE100 Index. Babcock International traces its history back to 1891 when the American Babcock & Wilcox Company formed a separately financed British company called Babcock & Wilcox Ltd. The UK companys sphere of operation was defined as the world except for North America, for a few years B&W boilers were built in the Singer Manufacturing Companys Kilbowie Works at Clydebank near Glasgow, Scotland. Isaac Singer was a significant shareholder in Babcock & Wilcox, in 1895 Babcock & Wilcox Ltd opened a new boilermaking works, based on the 33-acre site of the Porterfield Forge on the opposite side of the River Clyde near Renfrew. The Renfrew Works grew to over 200 acres by the 1960s, the workload expanded as a result of the two world wars and the supply of defence equipment became another major business area. During the 1940s the workforce at Renfrew peaked at approximately 10,000, in the 1960s the company became involved in the development of the UKs nuclear power stations. In 1979 Babcock & Wilcox Ltd was renamed Babcock International Ltd and this company was floated on the stock exchange in 1982, becoming Babcock International PLC. Babcock & Wilcox Ltd was renamed Babcock Power Ltd which subsequently became Babcock Energy Ltd, in 1987 Babcock merged with FKI Electricals plc, another engineering company to form FKI Babcock PLC. In February 1989 FKI Babcock PLC demerged to form Babcock International Group PLC, in 2006 Mitsui sold the company to Doosan Heavy Industries & Construction a subsidiary company of the Doosan Group of South Korea, at that time the UK company was renamed Doosan Babcock Energy Ltd. In 2009 the Czech-based steam turbine maker, Skoda Power, became part of Doosan Babcock Energy Ltd, in 2000 Babcock took the strategic decision to move away from manufacturing towards maintaining and supporting the critical equipment and infrastructure of customers. In 2002 Babcock was reclassified on the London Stock Exchange from Engineering to Support Services, on 19 June 2002 the Company acquired Service Group International Ltd, a provider of support services in defence and civil markets. It successfully bid for Peterhouse Group plc and on 18 June 2004 its bid was declared unconditional as over 50% of shares were held, on 30 September 2004 it acquired Turner and Partners, a provider of professional services to the telecoms industry. On 7 August 2007 acceptances for the acquisition of International Nuclear Solutions PLC reached 58. 9% of issued share capital and a take-over was then completed. On the 22 April 2008 to further strengthen the brand in the Nuclear sector and submarine support sector and this purchase brought a company with over 50 years of experience in high integrity material handling. In September 2009, Babcock acquired the UK Atomic Energy Authoritys commercial arm, in March 2010, Babcock acquired VT Group for £1. 32bn or 750p a share. Babcock offered 361. 6p a share in cash, as well as 0.7 new Babcock shares for each VT Group share, the acquisition was completed on 8 July 2010. The combined companies created a defence and support group with sales of £3bn and more than 25,000 employees in Britain
7.
Department for Business, Innovation and Skills
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It was disbanded on the creation of the Department for Business, Energy and Industrial Strategy on 14 July 2016. Following the departments dissolution, it no longer has ministers responsible, the Permanent Secretary was Sir Martin Donnelly. Economic policy is devolved but several important policy areas are reserved to Westminster. Further and higher education policy is mostly devolved, reserved and excepted matters are outlined below. Official website bis. gov. uk/ Archived Website Precursor departments, Department for Business and Regulatory Reform Archived Website Department for Innovation, Universities and Skills Archived Website
8.
Post Office Ltd
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The company is owned by the British Governments Department for Business, Innovation and Skills, through Postal Services Holding Company Limited. Post Office branches, along with the Royal Mail delivery service, were part of the General Post Office. Post Office Counters Ltd was created as an owned subsidiary of the Post Office corporation in 1986. After the Post Office corporation was renamed Royal Mail Group in 2001, Post Office Ltd has in recent years announced losses, a reported £102 million in 2006. This has raised concerns in the media regarding Post Office Ltds ability as a company to operate efficiently. Plans to cut the subsidy for rural post offices led to the announcement that 2,500 local post offices were to be closed. This announcement resulted in a backlash from local communities that relied on the service, in 2007, the government gave a £1.7 billion subsidy to Royal Mail Group so that it could turn a profit by 2011. This was to be used to invest across the network of Royal Mail, Post Office Ltd. 85 Crown post offices were closed,70 of which were sold to WHSmith and this followed a trial of six Post Office outlets in WHSmith stores. WHSmith was expected to make up to £2.5 million extra in annual profit,2,500 sub-post offices closed between 2008 and 2009. Redundancy packages were provided from public funding, in November 2010, the government committed £1.34 billion of funding up to 2015 to Post Office Ltd to enable it to modernise the Post Office network. As part of the Postal Services Act 2011, Post Office Ltd became independent of Royal Mail Group on 1 April 2012, a ten-year inter-business agreement was signed between the two companies to allow post offices to continue issuing stamps and handling letters and parcels for Royal Mail. The Act also contained the option for Post Office Ltd to become an organisation in the future. On 8 February 2013, Post Office Ltd announced it was planning to move around seventy of its Crown post offices into shops and this would reduce the Crown network, which it stated was losing £40 million a year, to around 300. On 27 November 2013, the government committed an additional £640 million of funding for 2015 to 2018 to allow Post Office Ltd to complete its network modernisation. There are currently around 11,500 post office branches across the UK, the majority of other branches are either run by various franchise partners or local subpostmaster or operators, as sub-postoffices. The Post Office has a variety of services throughout the network of branches. Products and services available vary throughout the network, main post offices generally provide the range of services
9.
Royal Observatory, Greenwich
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The Royal Observatory, Greenwich is an observatory situated on a hill in Greenwich Park, overlooking the River Thames. It played a role in the history of astronomy and navigation. The observatory was commissioned in 1675 by King Charles II, with the stone being laid on 10 August. The site was chosen by Sir Christopher Wren and he appointed John Flamsteed as the first Astronomer Royal. The building was completed in the summer of 1676, the building was often called Flamsteed House, in reference to its first occupant. The scientific work of the observatory was relocated elsewhere in stages in the first half of the 20th century,1675 –22 June, Royal Observatory founded. 1675 –10 August, construction began,1714 Longitude Act established the Board of Longitude and Longitude rewards. The Astronomer Royal was, until the Board was dissolved in 1828,1767 Astronomer Royal Nevil Maskelyne began publication of the Nautical Almanac, based on observations made at the Observatory. 1833 Daily time signals began, marked by dropping a Time ball,1899 The New Physical Observatory was completed. 1924 Hourly time signals from the Royal Observatory were first broadcast on 5 February,1948 Office of the Astronomer Royal was moved to Herstmonceux. 1957 Royal Observatory completed its move to Herstmonceux, becoming the Royal Greenwich Observatory, the Greenwich site is renamed the Old Royal Observatory. Greenwich site is returned to its name, the Royal Observatory. The Ordnance Office was given responsibility for building the Observatory, with Moore providing the key instruments, Moore donated two clocks, built by Thomas Tompion, which were installed in the 20 foot high Octagon Room, the principal room of the building. They were of unusual design, each with a pendulum 13 feet in length mounted above the face, giving a period of four seconds. British astronomers have used the Royal Observatory as a basis for measurement. Four separate meridians have passed through the buildings, defined by successive instruments, subsequently, nations across the world used it as their standard for mapping and timekeeping. When the Airy circle became the reference for the meridian, the difference resulting from the change was considered enough to be neglected. When a new triangulation was done between 1936 and 1962, scientists determined that in the Ordnance Survey system the longitude of the international Greenwich meridian was not 0° and this old astronomical prime meridian has been replaced by a more precise prime meridian
10.
Greenwich Mean Time
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Greenwich Mean Time is the mean solar time at the Royal Observatory in Greenwich, London. GMT was formerly used as the civil time standard, now superseded in that function by Coordinated Universal Time. Today GMT is considered equivalent to UTC for UK civil purposes and for navigation is considered equivalent to UT1, consequently, the term GMT should not be used for precise purposes. Due to Earths uneven speed in its orbit and its axial tilt, noon GMT is rarely the exact moment the sun crosses the Greenwich meridian. This event may occur up to 16 minutes before or after noon GMT, noon GMT is the annual average moment of this event, which accounts for the word mean in Greenwich Mean Time. Originally, astronomers considered a GMT day to start at noon while for almost everyone else it started at midnight, to avoid confusion, the name Universal Time was introduced to denote GMT as counted from midnight. Astronomers preferred the old convention to simplify their observational data, so each night was logged under a single calendar date. Today Universal Time usually refers to UTC or UT1, in some countries Greenwich Mean Time is the legal time in the winter and the population uses the term. For an explanation of why this is, see GMT in legislation below, synchronisation of the chronometer on GMT did not affect shipboard time, which was still solar time. Most time zones were based upon GMT, as an offset of a number of hours ahead of GMT or behind GMT and it was gradually adopted for other purposes, but a legal case in 1858 held local mean time to be the official time. On 14 May 1880, a signed by Clerk to Justices appeared in The Times, stating that Greenwich time is now kept almost throughout England. For example, our polling booths were opened, say, at 813 and closed at 413 PM. This was changed later in 1880, GMT was adopted on the Isle of Man in 1883, Jersey in 1898 and Guernsey in 1913. Ireland adopted GMT in 1916, supplanting Dublin Mean Time, hourly time signals from Greenwich Observatory were first broadcast on 5 February 1924, rendering the time ball at the observatory redundant in the process. The daily rotation of the Earth is irregular and constantly slows, on 1 January 1972, GMT was superseded as the international civil time standard by Coordinated Universal Time, maintained by an ensemble of atomic clocks around the world. Indeed, even the Greenwich meridian itself is not quite what it used to be—defined by the centre of the instrument at the Observatory at Greenwich. Nevertheless, the line in the old observatorys courtyard today differs no more than a few metres from that line which is now the prime meridian of the world. Historically GMT has been used two different conventions for numbering hours. The long-standing astronomical convention dating from the work of Ptolemy, was to refer to noon as zero hours and this contrasted with the civil convention of referring to midnight as zero hours dating from the Romans
11.
Frequency-shift keying
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Frequency-shift keying is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier signal. The technology is used for systems such as amateur radio, caller ID. The simplest FSK is binary FSK, BFSK uses a pair of discrete frequencies to transmit binary information. With this scheme, the 1 is called the mark frequency, the time domain of an FSK modulated carrier is illustrated in the figures to the right. Reference implementations of FSK modems exist and are documented in detail, the demodulation of a binary FSK signal can be done using the Goertzel algorithm very efficiently, even on low-power microcontrollers. In principle FSK can be implemented by using completely independent free-running oscillators, in general, independent oscillators will not be at the same phase and therefore the same amplitude at the switch-over instant, causing sudden discontinuities in the transmitted signal. In practice, many FSK transmitters use only a single oscillator, the elimination of discontinuities in the phase reduces sideband power, reducing interference with neighboring channels. This filter has the advantage of reducing power, reducing interference with neighboring channels. It is used by DECT, Bluetooth, Cypress WirelessUSB, Nordic Semiconductor, Texas Instruments LPRF, Z-Wave, for basic data rate Bluetooth the minimum deviation is 115 kHz. Gaussian filtering is a way for reducing spectral width, it is called pulse shaping in this application. In ordinary non-filtered FSK, at a jump from −1 to +1 or +1 to −1, the modulated waveform changes rapidly, if we change the pulse going from −1 to +1 as −1, −.98, −.93. +.93, +.98, +1, and we use this smoother pulse to determine the carrier frequency, minimum frequency-shift keying or minimum-shift keying is a particular spectrally efficient form of coherent FSK. In MSK, the difference between the higher and lower frequency is identical to half the bit rate, consequently, the waveforms that represent a 0 and a 1 bit differ by exactly half a carrier period. The maximum frequency deviation is δ =0.25 fm, as a result, the modulation index m is 0.5. This is the smallest FSK modulation index that can be such that the waveforms for 0 and 1 are orthogonal. A variant of MSK called Gaussian minimum shift keying is used in the GSM mobile phone standard, normally, the transmitted audio alternates between two tones, one, the mark, represents a binary one, the other, the space, represents a binary zero. AFSK differs from regular frequency-shift keying in performing the modulation at baseband frequencies, in radio applications, the AFSK-modulated signal normally is being used to modulate an RF carrier for transmission. AFSK is not always used for high-speed data communications, since it is far less efficient in both power and bandwidth than most other modulation modes
12.
Morse code
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Morse code is a method of transmitting text information as a series of on-off tones, lights, or clicks that can be directly understood by a skilled listener or observer without special equipment. It is named for Samuel F. B, Morse, an inventor of the telegraph. Because many non-English natural languages use more than the 26 Roman letters, each Morse code symbol represents either a text character or a prosign and is represented by a unique sequence of dots and dashes. The duration of a dash is three times the duration of a dot, each dot or dash is followed by a short silence, equal to the dot duration. The letters of a word are separated by an equal to three dots, and the words are separated by a space equal to seven dots. The dot duration is the unit of time measurement in code transmission. To increase the speed of the communication, the code was designed so that the length of each character in Morse varies approximately inversely to its frequency of occurrence in English. Thus the most common letter in English, the letter E, has the shortest code, Morse code is used by some amateur radio operators, although knowledge of and proficiency with it is no longer required for licensing in most countries. Pilots and air controllers usually need only a cursory understanding. Aeronautical navigational aids, such as VORs and NDBs, constantly identify in Morse code, compared to voice, Morse code is less sensitive to poor signal conditions, yet still comprehensible to humans without a decoding device. Morse is, therefore, an alternative to synthesized speech for sending automated data to skilled listeners on voice channels. Many amateur radio repeaters, for example, identify with Morse, in an emergency, Morse code can be sent by improvised methods that can be easily keyed on and off, making it one of the simplest and most versatile methods of telecommunication. The most common signal is SOS or three dots, three dashes, and three dots, internationally recognized by treaty. Beginning in 1836, the American artist Samuel F. B, Morse, the American physicist Joseph Henry, and Alfred Vail developed an electrical telegraph system. This system sent pulses of current along wires which controlled an electromagnet that was located at the receiving end of the telegraph system. A code was needed to transmit natural language using only these pulses, around 1837, Morse, therefore, developed an early forerunner to the modern International Morse code. Around the same time, Carl Friedrich Gauss and Wilhelm Eduard Weber as well as Carl August von Steinheil had already used codes with varying lengths for their telegraphs. In 1837, William Cooke and Charles Wheatstone in England began using a telegraph that also used electromagnets in its receivers
13.
Geographic coordinate system
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A geographic coordinate system is a coordinate system used in geography that enables every location on Earth to be specified by a set of numbers, letters or symbols. The coordinates are chosen such that one of the numbers represents a vertical position. A common choice of coordinates is latitude, longitude and elevation, to specify a location on a two-dimensional map requires a map projection. The invention of a coordinate system is generally credited to Eratosthenes of Cyrene. Ptolemy credited him with the adoption of longitude and latitude. Ptolemys 2nd-century Geography used the prime meridian but measured latitude from the equator instead. Mathematical cartography resumed in Europe following Maximus Planudes recovery of Ptolemys text a little before 1300, in 1884, the United States hosted the International Meridian Conference, attended by representatives from twenty-five nations. Twenty-two of them agreed to adopt the longitude of the Royal Observatory in Greenwich, the Dominican Republic voted against the motion, while France and Brazil abstained. France adopted Greenwich Mean Time in place of local determinations by the Paris Observatory in 1911, the latitude of a point on Earths surface is the angle between the equatorial plane and the straight line that passes through that point and through the center of the Earth. Lines joining points of the same latitude trace circles on the surface of Earth called parallels, as they are parallel to the equator, the north pole is 90° N, the south pole is 90° S. The 0° parallel of latitude is designated the equator, the plane of all geographic coordinate systems. The equator divides the globe into Northern and Southern Hemispheres, the longitude of a point on Earths surface is the angle east or west of a reference meridian to another meridian that passes through that point. All meridians are halves of great ellipses, which converge at the north and south poles, the prime meridian determines the proper Eastern and Western Hemispheres, although maps often divide these hemispheres further west in order to keep the Old World on a single side. The antipodal meridian of Greenwich is both 180°W and 180°E, the combination of these two components specifies the position of any location on the surface of Earth, without consideration of altitude or depth. The grid formed by lines of latitude and longitude is known as a graticule, the origin/zero point of this system is located in the Gulf of Guinea about 625 km south of Tema, Ghana. To completely specify a location of a feature on, in, or above Earth. Earth is not a sphere, but a shape approximating a biaxial ellipsoid. It is nearly spherical, but has an equatorial bulge making the radius at the equator about 0. 3% larger than the radius measured through the poles, the shorter axis approximately coincides with the axis of rotation
14.
Rugby Radio Station
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Its large very low frequency transmitter came into service on 1 January 1926 and was originally used to transmit telegraph messages to the Commonwealth as part of the Imperial Wireless Chain. Criggion radio station acted as a reserve, the GBR transmitter was shut down on 1 April 2003 and was replaced by a new one at the Skelton transmitting station. In 1927, a transmitter was installed to initiate the first transatlantic commercial telephone service, linking New York. This transmitter was decommissioned in 1956 and became the signal transmitter MSF. This new function developed from the decision, in 1951, to use the station to transmit modulated standard frequencies for scientific reference purposes, in 1972 these transmissions were consolidated onto the present frequency of 60 kHz and a further reference, that of a time signal, was added. The aerial system at the VLF transmitter existed between 1926 and 2004 and consisted of twelve 250 metre high, guyed masts insulated against ground. This wire was destroyed by heavy iceloads in the winter of 1940. After the shutdown of GBR, the facility was used for transmitting the MSF time signal. Therefore, eight of the masts were obsolete and demolished on the night of 19 June 2004 to 20 June 2004. The remaining four tall masts were demolished on 2 August 2007
15.
Rugby, Warwickshire
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Rugby is a market town in Warwickshire, England, close to the River Avon. The town has a population of 70,628 making it the second largest town in the county, the enclosing Borough of Rugby has a population of 100,500. Rugby is 13 miles east of Coventry, on the edge of Warwickshire. The town is credited with being the birthplace of rugby football, Early Iron age settlement existed in the Rugby area, and a few miles outside what is now Rugby, existed a Roman settlement known as Tripontium. Rugby was originally a small Anglo-Saxon farming settlement, and was mentioned in the Domesday Book of 1086 as Rocheberie, Rugby obtained a charter to hold a market in 1255, and soon developed into a small country market town. Rugby School was founded in 1567 with money left in the will of Lawrence Sheriff, a locally born grocer, Rugby School was originally intended as a school for local boys, but over time became a mostly fee-paying private school. The Lawrence Sheriff School was eventually founded in the late 19th century to carry on Sheriffs original intentions, Rugby remained a sleepy country market town until the 19th century and the coming of the railways. In 1838 the London and Birmingham Railway was constructed past it, Rugby became an important railway junction, and the proliferation of rail yards and workshops attracted workers. Rugbys population grew from just 2,500 in 1835, to over 10,000 by the 1880s, in the 1890s and 1900s heavy engineering industries began to set up in the town, and Rugby rapidly grew into a major industrial centre. Rugby expanded rapidly in the decades of the 20th century as workers moved in. By the 1940s, the population of Rugby had grown to over 40,000, in the postwar years, Rugby became well served by the motorway network, with the M1 and M6 merging close to the town. Rugby is most famous for the invention of rugby football, which is played throughout the world, the invention of the game is credited to William Webb Ellis whilst breaking the existing rules of a football match played in 1823 at Rugby School. Rugby School is one of Englands oldest and most prestigious public schools, a substantial part of the 2004 dramatisation of the novel, starring Stephen Fry, was filmed on location at Rugby School. Hughes later set up a colony in America for the sons of the English gentry. The town of Rugby, Tennessee still exists, Rugby is a birthplace of the jet engine. Much of his work was carried out at nearby Lutterworth, holography was invented in Rugby by the Hungarian inventor Dennis Gabor in 1947. In the 19th century, Rugby became famous for its once important railway junction which was the setting for Charles Dickenss story Mugby Junction, Rugby also includes the areas of New Bilton, Overslade and Hillside. The spread of Rugby has nearly reached the villages of Clifton-upon-Dunsmore, Cawston, Dunchurch, the town centre is mostly Victorian and early 20th century, however a few much older buildings survive, along with some more modern developments
16.
Call sign
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In broadcasting and radio communications, a call sign is a unique designation for a transmitter station. In North America, they are used for all FCC licensed transmitters, a call sign can be formally assigned by a government agency, informally adopted by individuals or organizations, or even cryptographically encoded to disguise a stations identity. The use of signs as unique identifiers dates to the landline railroad telegraph system. Because there was only one line linking all railroad stations. In order to time, two-letter identifiers were adopted for this purpose. This pattern continued in operation, radio companies initially assigned two-letter identifiers to coastal stations and stations aboard ships at sea. These were not globally unique, so a company identifier was later added. Merchant and naval vessels are assigned call signs by their national licensing authorities, in the case of states such as Liberia or Panama, which are flags of convenience for ship registration, call signs for larger vessels consist of the national prefix plus three letters. United States merchant vessels are given call signs beginning with the letters W or K while US naval ships are assigned callsigns beginning with N, leisure craft with VHF radios may not be assigned call signs, in which case the name of the vessel is used instead. Ships in the US wishing to have a radio licence anyway are under F. C. C, class SA, Ship recreational or voluntarily equipped. Those calls follow the land mobile format of the initial letter K or W followed by 1 or 2 letters followed by 3 or 4 numbers. U. S. Coast Guard small boats have a number that is shown on both bows in which the first two digits indicate the length of the boat in feet. For example, Coast Guard 47021 refers to the 21st in the series of 47 foot motor lifeboats, the call sign might be abbreviated to the final two or three numbers during operations, for example, Coast Guard zero two one. Call signs in aviation are derived from several different policies, depending upon the type of flight operation, in most countries, unscheduled general aviation flights identify themselves using the call sign corresponding to the aircrafts registration number. In this case, the sign is spoken using the International Civil Aviation Organization phonetic alphabet. Aircraft registration numbers internationally follow the pattern of a country prefix, for example, an aircraft registered as N978CP conducting a general aviation flight would use the call sign November-niner-seven-eight-Charlie-Papa. However, in the United States a pilot of an aircraft would normally omit saying November, at times, general aviation pilots might omit additional preceding numbers and use only the last three numbers and letters. This is especially true at uncontrolled fields when reporting traffic pattern positions, for example, Skyhawk eight-Charlie-Papa, left base
17.
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
18.
Kilowatt
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The watt is a derived unit of power in the International System of Units defined as 1 joule per second and can be used to quantify the rate of energy transfer. Power has dimensions of M L2 T −3, when an objects velocity is held constant at one meter per second against constant opposing force of one newton the rate at which work is done is 1 watt. 1 W =1 V ⋅ A Two additional unit conversions for watt can be using the above equation. 1 W =1 V2 Ω =1 A2 ⋅ Ω Where ohm is the SI derived unit of electrical resistance, a person having a mass of 100 kilograms who climbs a 3-meter-high ladder in 5 seconds is doing work at a rate of about 600 watts. Mass times acceleration due to gravity times height divided by the time it takes to lift the object to the given height gives the rate of doing work or power. A laborer over the course of an 8-hour day can sustain an output of about 75 watts, higher power levels can be achieved for short intervals. The watt is named after the Scottish scientist James Watt for his contributions to the development of the steam engine, in 1960 the 11th General Conference on Weights and Measures adopted it for the measurement of power into the International System of Units. For additional examples of magnitude for multiples and submultiples of the watt, technologically important powers that are measured in femtowatts are typically found in reference to radio and radar receivers. For example, meaningful FM tuner performance figures for sensitivity, quieting and these input levels are often stated in dBf. This is 0.2739 microvolt across a 75-ohm load or 0.5477 microvolt across a 300-ohm load, the picowatt is equal to one trillionth of a watt. Technologically important powers that are measured in picowatts are typically used in reference to radio and radar receivers, acoustics, the nanowatt is equal to one billionth of a watt. Important powers that are measured in nanowatts are also used in reference to radio. The microwatt is equal to one millionth of a watt, compact solar cells for devices such as calculators and watches are typically measured in microwatts. The milliwatt is equal to one thousandth of a watt, a typical laser pointer outputs about five milliwatts of light power, whereas a typical hearing aid for people uses less than one milliwatt. Audio signals and other electronic signal levels are measured in dBm. The kilowatt is equal to one thousand watts and this unit is typically used to express the output power of engines and the power of electric motors, tools, machines, and heaters. It is also a unit used to express the electromagnetic power output of broadcast radio. One kilowatt is equal to 1.34 horsepower
19.
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
20.
Mains electricity
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Mains electricity is the general-purpose alternating-current electric power supply. The two principal properties of the power supply, voltage and frequency, differ between regions. A voltage of 230 V and a frequency of 50 Hz is used in Europe, most of Africa, most of Asia, most of South America, in North America, the most common combination is 120 V and a frequency of 60 Hz. Other voltages exist, and some countries may have, for example,230 V but 60 Hz and this is a concern to travelers, since portable appliances designed for one voltage and frequency combination may not operate with or may be destroyed by another. In the UK, mains power is generally referred to as the mains. All these parameters vary among regions, the voltages are generally in the range 100–240 V. The two commonly used frequencies are 50 Hz and 60 Hz, single-phase or three-phase power is most commonly used today, although two-phase systems were used early in the 20th century. Foreign enclaves, such as industrial plants or overseas military bases. Some city areas may use different from that of the surrounding countryside. Regions in a state of anarchy may have no central electrical authority. Many other combinations of voltage and utility frequency were formerly used, direct current has been almost completely displaced by alternating current in public power systems, but DC was used especially in some city areas to the end of the 20th century. The modern combinations of 230 V/50 Hz and 120 V/60 Hz, listed in IEC60038, electricity is used for lighting, heating, cooling, electric motors and electronic equipment. The U. S. Energy Information Administration has published, Estimated U. S.3 Does not include water heating,4 Includes small electric devices, heating elements, and motors which are not listed above. Does not include electric vehicle charging, electronic appliances, typically use an AC to DC converter to power the device, this is often capable of operation over the approximate range of 100 V to 250 V and at 50 Hz to 60 Hz. The other categories are typically AC applications and usually have more restricted input ranges. A study by the Building Research Establishment in the UK states that The existing 230 V system is suited to the future of electricity whether through design or Darwinian processes. Any current perceived weakness is generally a result of cost reduction, questions as to whether there are alternatives to the existing 230 V AC system are often overshadowed by legacy issues, the future smart agenda and cost in all but specific situations. Where opportunities do exist they are often for specific parts of the overall load, in many countries, household power is single-phase electric power, with two or three wired contacts at each outlet
21.
T-antenna
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A T-antenna, T-aerial, flat-top antenna, or top-hat antenna is a vertically polarized simple wire radio antenna used in the VLF, LF, MF and shortwave bands. T-antennas are widely used as transmitting antennas for radio stations, long wave. They are also used as receiving antennas for shortwave listening, the antenna consists of one or more horizontal wires suspended between two supporting radio masts or buildings and insulated from them at the ends. A vertical wire is connected to the center of the wires and hangs down close to the ground. Combined, the two form a T shape, hence the name. The transmitter power is applied, or the receiver is connected, the T-antenna functions as a monopole antenna with capacitive top-loading, other antennas in this category include the inverted-L, umbrella, delta, and triatic antennas. It was invented during the first decades of radio, in the wireless telegraphy era, instead it serves to add capacitance to the top of the antenna. The top load wire can increase radiated power by 2 to 4 times for a given base current, however, the antenna is still typically not as efficient as a full-height λ/4 vertical monopole, and has a higher Q and thus a narrower bandwidth. 1λ or less. Since the radiation resistance and efficiency increases with height, the antenna should be suspended as high as possible, the antenna has a base impedance with a capacitive component that must be tuned out with an added inductor. To increase the capacitance, several parallel horizontal wires are often used, connected together at the center where the vertical wire attaches. The capacitance does not increase proportionally with the number of wires, however, since the vertical wire is the actual radiating element, the antenna radiates vertically polarized radio waves in an omnidirectional radiation pattern, with equal power in all azimuthal directions. The axis of the horizontal wire makes little difference, the power is maximum in a horizontal direction or at a shallow elevation angle, decreasing to zero at the zenith. The effect of ground conductivity is generally to tilt the pattern up. Since it is shorter than λ/4 the T antenna has a capacitive reactance. To operate over a frequency range the loading coil often must be adjustable. The high Q also causes a voltage on the antenna. The insulators at the ends must be designed to withstand these voltages, in high power transmitters the output power is often limited by the onset of corona discharge on the wires. At low frequencies the resistance is very low, often less than an ohm
22.
Omnidirectional antenna
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This radiation pattern is often described as doughnut shaped. Note that this is different from an antenna, which radiates equal power in all directions and has a spherical radiation pattern. Higher-gain omnidirectional antennas can also be built, higher gain in this case means that the antenna radiates less energy at higher and lower elevation angles and more in the horizontal directions. High-gain omnidirectional antennas are generally realized using collinear dipole arrays and these consist of multiple half-wave dipoles mounted collinearly, fed in phase. The coaxial collinear antenna uses transposed coaxial sections to produce in-phase half-wavelength radiators, a Franklin Array uses short U-shaped half-wavelength sections whose radiation cancels in the far-field to bring each half-wavelength dipole section into equal phase. Another type is the Omnidirectional Microstrip Antenna, Omnidirectional radiation patterns are produced by the simplest practical antennas, monopole and dipole antennas, consisting of one or two straight rod conductors on a common axis. Antenna gain is defined as antenna efficiency multiplied by antenna directivity which is expressed mathematically as, G = e D. A useful relationship between omnidirectional radiation pattern directivity in decibels and half-power beamwidth based on the assumption of a sin b θ / b θ pattern shape is, D =10 log 10 d B
23.
Radio clock
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A radio clock or radio-controlled clock is a clock that is automatically synchronized by a time code transmitted by a radio transmitter connected to a time standard such as an atomic clock. Such a clock may be synchronized to the time sent by a transmitter, such as many national or regional time transmitters, or may use multiple transmitters. Such systems may be used to set clocks or for any purpose where accurate time is needed. The radio controlled clock will contain a time base oscillator to maintain timekeeping if the radio signal is momentarily unavailable. Other radio controlled clocks use the signals transmitted by dedicated transmitters in the shortwave bands. Systems using dedicated time signal stations can achieve accuracy of a few tens of milliseconds, GPS satellite navigation receivers also internally generate accurate time information from the satellite signals. General purpose or consumer grade GPS may have an offset of up to one second between the calculated time, which is much more accurate than 1 second, and the time displayed on the screen. Other broadcast services may include timekeeping information of varying accuracy within their signals, Radio clocks depend on coded time signals from radio stations. The stations vary in broadcast frequency, in location. In general, each station has its own format for the time code, many other countries can receive these signals, but success depends on the time of day, atmospheric conditions, and interference from intervening buildings. Reception is generally better if the clock is placed near a window facing the transmitter, there is also a transit delay of approximately 1 ms for every 300 km the receiver is from the transmitter. A number of manufacturers and retailers sell radio clocks that receive coded time signals from a radio station, one of the first radio clocks was offered by Heathkit in late 1983. Their model GC-1000 Most Accurate Clock received shortwave time signals from radio station WWV in Fort Collins and it automatically switched between WWVs 5,10, and 15 MHz frequencies to find the strongest signal as conditions changed through the day and year. It kept time during periods of poor reception with a quartz-crystal oscillator and this oscillator was disciplined, meaning that the microprocessor-based clock used the highly accurate time signal received from WWV to trim the crystal oscillator. The timekeeping between updates was thus more accurate than the crystal alone could have achieved. Time down to the tenth of a second was shown on an LED display, the GC-1000 originally sold for US$250 in kit form, US$400 preassembled, and was considered impressive at the time. Heath Company was granted a patent for its design, in the 2000s radio-based atomic clocks became common in retail stores, as of 2010 prices start at around US$15 in many countries. Clocks may have features such as indoor thermometers and weather station functionality
24.
Summer time
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Typically, regions that use daylight saving time adjust clocks forward one hour close to the start of spring and adjust them backward in the autumn to standard time. American inventor and politician Benjamin Franklin proposed a form of time in 1784. New Zealander George Hudson proposed the idea of saving in 1895. The German Empire and Austria-Hungary organized the first nationwide implementation, starting on April 30,1916, many countries have used it at various times since then, particularly since the energy crisis of the 1970s. The practice has both advocates and critics, DST clock shifts sometimes complicate timekeeping and can disrupt travel, billing, record keeping, medical devices, heavy equipment, and sleep patterns. Computer software often adjusts clocks automatically, but policy changes by various jurisdictions of DST dates, industrialized societies generally follow a clock-based schedule for daily activities that do not change throughout the course of the year. The time of day that individuals begin and end work or school, North and south of the tropics daylight lasts longer in summer and shorter in winter, with the effect becoming greater as one moves away from the tropics. However, they will have one hour of daylight at the start of each day. Supporters have also argued that DST decreases energy consumption by reducing the need for lighting and heating, DST is also of little use for locations near the equator, because these regions see only a small variation in daylight in the course of the year. After ancient times, equal-length civil hours eventually supplanted unequal, so civil time no longer varies by season, unequal hours are still used in a few traditional settings, such as some monasteries of Mount Athos and all Jewish ceremonies. This 1784 satire proposed taxing window shutters, rationing candles, and waking the public by ringing church bells, despite common misconception, Franklin did not actually propose DST, 18th-century Europe did not even keep precise schedules. However, this changed as rail transport and communication networks came to require a standardization of time unknown in Franklins day. Modern DST was first proposed by the New Zealand entomologist George Hudson, whose shift work job gave him time to collect insects. An avid golfer, he also disliked cutting short his round at dusk and his solution was to advance the clock during the summer months, a proposal he published two years later. The proposal was taken up by the Liberal Member of Parliament Robert Pearce, a select committee was set up to examine the issue, but Pearces bill did not become law, and several other bills failed in the following years. Willett lobbied for the proposal in the UK until his death in 1915, william Sword Frost, mayor of Orillia, Ontario, introduced daylight saving time in the municipality during his tenure from 1911 to 1912. Starting on April 30,1916, the German Empire and its World War I ally Austria-Hungary were the first to use DST as a way to conserve coal during wartime, Britain, most of its allies, and many European neutrals soon followed suit. Russia and a few other countries waited until the year
25.
On-off keying
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On-off keying denotes the simplest form of amplitude-shift keying modulation that represents digital data at the presence or absence of a carrier wave. In its simplest form, the presence of a carrier for a specific duration represents a binary one, some more sophisticated schemes vary these durations to convey additional information. It is analogous to unipolar encoding line code, on-off keying is most commonly used to transmit Morse code over radio frequencies, although in principle any digital encoding scheme may be used. OOK has been used in the ISM bands to transfer data between computers, for example, OOK is more spectrally efficient than frequency-shift keying, but more sensitive to noise when using a regenerative receiver or a poorly implemented superheterodyne receiver. For a given rate, the bandwidth of a BPSK signal. In addition to RF carrier waves, OOK is also used in communication systems. Unipolar encoding Application Note - Im OOK
26.
Coordinated Universal Time
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Coordinated Universal Time, abbreviated to UTC, is the primary time standard by which the world regulates clocks and time. It is within about 1 second of mean time at 0° longitude. It is one of closely related successors to Greenwich Mean Time. For most purposes, UTC is considered interchangeable with GMT, the first Coordinated Universal Time was informally adopted on 1 January 1960. This change also adopted leap seconds to simplify future adjustments, a number of proposals have been made to replace UTC with a new system that would eliminate leap seconds, but no consensus has yet been reached. Leap seconds are inserted as necessary to keep UTC within 0.9 seconds of universal time, see the Current number of leap seconds section for the number of leap seconds inserted to date. The official abbreviation for Coordinated Universal Time is UTC and this abbreviation arose from a desire by the International Telecommunication Union and the International Astronomical Union to use the same abbreviation in all languages. English speakers originally proposed CUT, while French speakers proposed TUC, the compromise that emerged was UTC, which conforms to the pattern for the abbreviations of the variants of Universal Time. Time zones around the world are expressed using positive or negative offsets from UTC, the westernmost time zone uses UTC−12, being twelve hours behind UTC, the easternmost time zone, theoretically, uses UTC+12, being twelve hours ahead of UTC. In 1995, the nation of Kiribati moved those of its atolls in the Line Islands from UTC-10 to UTC+14 so that the country would all be on the same day. UTC is used in internet and World Wide Web standards. The Network Time Protocol, designed to synchronise the clocks of computers over the internet, computer servers, online services and other entities that rely on having a universally accepted time use UTC as it is more specific than GMT. If only limited precision is needed, clients can obtain the current UTC from a number of official internet UTC servers, for sub-microsecond precision, clients can obtain the time from satellite signals. UTC is also the standard used in aviation, e. g. for flight plans. Weather forecasts and maps all use UTC to avoid confusion about time zones, the International Space Station also uses UTC as a time standard. Amateur radio operators often schedule their radio contacts in UTC, because transmissions on some frequencies can be picked up by many time zones, UTC is also used in digital tachographs used on large goods vehicles under EU and AETR rules. UTC divides time into days, hours, minutes and seconds, days are conventionally identified using the Gregorian calendar, but Julian day numbers can also be used. Each day contains 24 hours and each hour contains 60 minutes, the number of seconds in a minute is usually 60, but with an occasional leap second, it may be 61 or 59 instead
27.
UT1
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Universal Time is a time standard based on Earths rotation. It is a continuation of Greenwich Mean Time, i. e. the mean solar time on the Prime Meridian at Greenwich, London. In fact, the expression Universal Time is ambiguous, as there are versions of it. All of these versions of UT, except for UTC, are based on Earths rotation relative to distant celestial objects, UTC is based on International Atomic Time, with leap seconds added to keep it within 0.9 second of UT1. Prior to the introduction of time, each municipality throughout the civilized world set its official clock, if it had one. Greenwich Mean Time, where all clocks in Britain were set to the time, was established to solve this problem. Chronometers or telegraphy were used to synchronize these clocks, Standard time, as originally proposed by Scottish-Canadian Sir Sandford Fleming in 1879, divided the world into twenty-four time zones, each one covering 15 degrees of longitude. All clocks within each zone would be set to the time as the others. This location was chosen because by 1884 two-thirds of all nautical charts, the conference did not adopt Flemings time zones because they were outside the purpose for which it was called, which was to choose a basis for universal time. During the period between 1848 and 1972, all of the countries adopted time zones based on the Greenwich meridian. The term Greenwich Mean Time persists, however, in usage to this day in reference to civil timekeeping. Based on the rotation of the Earth, time can be measured by observing celestial bodies crossing the meridian every day. Astronomers found that it was accurate to establish time by observing stars as they crossed a meridian rather than by observing the position of the Sun in the sky. Nowadays, UT in relation to International Atomic Time is determined by Very Long Baseline Interferometry observations of distant quasars, the rotation of the Earth and UT are monitored by the International Earth Rotation and Reference Systems Service. The International Astronomical Union also is involved in setting standards, the rotation of the Earth is somewhat irregular, and is very gradually slowing due to tidal acceleration. Furthermore, the length of the second was determined from observations of the Moon between 1750 and 1890. All of these cause the mean solar day, on the average, to be slightly longer than the nominal 86,400 SI seconds. As UT is slightly irregular in its rate, astronomers introduced Ephemeris Time, thus, civil broadcast standards for time and frequency usually follow International Atomic Time closely, but occasionally step in order to prevent them from drifting too far from mean solar time
28.
Minute
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The minute is a unit of time or of angle. As a unit of time, the minute is equal to 1⁄60 of an hour, in the UTC time standard, a minute on rare occasions has 61 seconds, a consequence of leap seconds. As a unit of angle, the minute of arc is equal to 1⁄60 of a degree, although not an SI unit for either time or angle, the minute is accepted for use with SI units for both. The SI symbols for minute or minutes are min for time measurement, the prime is also sometimes used informally to denote minutes of time. In contrast to the hour, the minute does not have a historical background. What is traceable only is that it started being recorded in the Middle Ages due to the ability of construction of precision timepieces, however, no consistent records of the origin for the division as 1⁄60 part of the hour have ever been found, despite many speculations. Historically, the word comes from the Latin pars minuta prima. This division of the hour can be refined with a second small part. For even further refinement, the third remains in some languages, for example Polish and Turkish. The symbol notation of the prime for minutes and double prime for seconds can be seen as indicating the first, international System of Units Latitude and longitude Orders of magnitude Henry Campbell Black, Blacks Law Dictionary, 6th Edition, entry on Minute. West Publishing Company, St. Paul, Minnesota,1991
29.
Second
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The second is the base unit of time in the International System of Units. It is qualitatively defined as the division of the hour by sixty. SI definition of second is the duration of 9192631770 periods of the corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom. Seconds may be measured using a mechanical, electrical or an atomic clock, SI prefixes are combined with the word second to denote subdivisions of the second, e. g. the millisecond, the microsecond, and the nanosecond. Though SI prefixes may also be used to form multiples of the such as kilosecond. The second is also the unit of time in other systems of measurement, the centimetre–gram–second, metre–kilogram–second, metre–tonne–second. Absolute zero implies no movement, and therefore zero external radiation effects, the second thus defined is consistent with the ephemeris second, which was based on astronomical measurements. The realization of the second is described briefly in a special publication from the National Institute of Standards and Technology. 1 international second is equal to, 1⁄60 minute 1⁄3,600 hour 1⁄86,400 day 1⁄31,557,600 Julian year 1⁄, more generally, = 1⁄, the Hellenistic astronomers Hipparchus and Ptolemy subdivided the day into sixty parts. They also used an hour, simple fractions of an hour. No sexagesimal unit of the day was used as an independent unit of time. The modern second is subdivided using decimals - although the third remains in some languages. The earliest clocks to display seconds appeared during the last half of the 16th century, the second became accurately measurable with the development of mechanical clocks keeping mean time, as opposed to the apparent time displayed by sundials. The earliest spring-driven timepiece with a hand which marked seconds is an unsigned clock depicting Orpheus in the Fremersdorf collection. During the 3rd quarter of the 16th century, Taqi al-Din built a clock with marks every 1/5 minute, in 1579, Jost Bürgi built a clock for William of Hesse that marked seconds. In 1581, Tycho Brahe redesigned clocks that displayed minutes at his observatory so they also displayed seconds, however, they were not yet accurate enough for seconds. In 1587, Tycho complained that his four clocks disagreed by plus or minus four seconds, in 1670, London clockmaker William Clement added this seconds pendulum to the original pendulum clock of Christiaan Huygens. From 1670 to 1680, Clement made many improvements to his clock and this clock used an anchor escapement mechanism with a seconds pendulum to display seconds in a small subdial
30.
Leap second
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A leap second is a one-second adjustment that is occasionally applied to Coordinated Universal Time in order to keep its time of day close to the mean solar time, or UT1. Without such a correction, time reckoned by Earths rotation drifts away from atomic time because of irregularities in the Earths rate of rotation. Since this system of correction was implemented in 1972,27 leap seconds have been inserted, like most time standards, UTC defines a grouping of seconds into minutes, hours, days, months, and years. However, the duration of one solar day is now slightly longer than 24 hours because the rotation of the Earth has slowed down. The purpose of a second is to compensate for this drift. Specifically, a leap second is inserted between second 23,59,59 of a chosen UTC calendar date and second 00,00,00 of the following date. All leap seconds have been scheduled for either June 30 or December 31, the extra second is displayed on UTC clocks as 23,59,60. On clocks that display local time tied to UTC, the second may be inserted at the end of some other hour. A negative leap second would suppress second 23,59,59 of the last day of a chosen month, since the introduction of leap seconds, the mean solar day has outpaced UTC only for very brief periods, and has not triggered a negative leap second. Because the Earths rotation speed varies in response to climatic and geological events, UTC leap seconds are irregularly spaced, with this definition, the second was proposed in 1874 as the base unit of time in the CGS system of units. Because the tropical year was considered more fundamental than the year, in 1955. That value agreed to 1 part in 1010 with the second then in use. It was also close to 1⁄86400 of the solar day as averaged between years 1750 and 1892. However, for the past several centuries, the length of the solar day has been increasing by about 1. 4–1.7 ms per century. By 1961, the solar day was already a millisecond or two longer than 86,400 SI seconds. Thus, from 1961 to 1971, the rate of clocks was constantly slowed to remain synchronised with GMT. During that period, therefore, the seconds of broadcast services were actually longer than the SI second. By then, the UTC clock was already 10 seconds behind TAI, which had been synchronized with UT1 in 1958, but had been counting true SI seconds since then
31.
Binary-coded decimal
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In computing and electronic systems, binary-coded decimal is a class of binary encodings of decimal numbers where each decimal digit is represented by a fixed number of bits, usually four or eight. Special bit patterns are used for a sign or for other indications. The precise 4-bit encoding may vary however, for technical reasons, the ten states representing a BCD decimal digit are sometimes called tetrades with those dont care-states unused named pseudo-tetrads or pseudo-decimal digit). BCDs principal drawbacks are an increase in the complexity of the circuits needed to implement basic arithmetics. BCD was used in many early computers, and is implemented in the instruction set of machines such as the IBM System/360 series and its descendants. BCD takes advantage of the fact that any one decimal numeral can be represented by a four bit pattern, the most obvious way of encoding digits is natural BCD, where each decimal digit is represented by its corresponding four-bit binary value, as shown in the following table. This is also called 8421 encoding, other encodings are also used, including so-called 4221 and 7421 — named after the weighting used for the bits — and excess-3. For example, the BCD digit 6, 0110b in 8421 notation, is 1100b in 4221, 0110b in 7421, Packed, Two numerals are encoded into a single byte, with one numeral in the least significant nibble and the other numeral in the most significant nibble. To represent numbers larger than the range of a single byte any number of contiguous bytes may be used, also note how packed BCD is more efficient in storage usage as compared to unpacked BCD, encoding the same number in unpacked format would consume twice the storage. Shifting and masking operations are used to pack or unpack a packed BCD digit, other logical operations are used to convert a numeral to its equivalent bit pattern or reverse the process. BCD is very common in systems where a numeric value is to be displayed, especially in systems consisting solely of digital logic. By employing BCD, the manipulation of data for display can be greatly simplified by treating each digit as a separate single sub-circuit. This matches much more closely the reality of display hardware—a designer might choose to use a series of separate identical seven-segment displays to build a metering circuit. If the numeric quantity were stored and manipulated as pure binary, therefore, in cases where the calculations are relatively simple, working throughout with BCD can lead to a simpler overall system than converting to and from binary. Most pocket calculators do all their calculations in BCD, the same argument applies when hardware of this type uses an embedded microcontroller or other small processor. Often, smaller code results when representing numbers internally in BCD format, for these applications, some small processors feature BCD arithmetic modes, which assist when writing routines that manipulate BCD quantities. In Packed BCD, each of the two nibbles of each byte represent a decimal digit, Packed BCD has been in use since at least the 1960s and is implemented in all IBM mainframe hardware since then. Most implementations are big endian, i. e. with the more significant digit in the half of each byte
32.
Greenwich Time Signal
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The Greenwich Time Signal, popularly known as the pips, is a series of six short tones broadcast at one-second intervals by many BBC Radio stations. The pips were introduced in 1924 and have been generated by the BBC since 1990 to mark the start of each hour. Their utility in calibration is diminishing as digital broadcasting entails time lags, there are six pips in total, which occur on the 5 seconds leading up to the hour and on the hour itself. Each pip is a 1 kHz tone the first five of which last a tenth of a second each, the actual moment when the hour changes – the on-time marker – is at the very beginning of the last pip. When a leap occurs, it is indicated by a seventh pip. In this case the first pip occurs at 23,59,55, the possibility of an extra pip for the leap second thus justifies the final pip being longer than the others, so that it is always clear which pip is on the hour. Before leap seconds were conceived, the final pip was the length as the others. Although negative leap seconds can also be used to make the year shorter, although normally broadcast only on the hour by BBC domestic radio, BBC World Service use the signal at other times as well. The signal is generated at each quarter-hour and has on occasion been broadcast in error, the pips are available to BBC radio stations every 15 minutes but except in rare cases, they are only broadcast on the hour, usually before news bulletins or news programmes. On BBC Radio 4, the pips are broadcast every hour except at 18,00 and 00,00, no time signal is broadcast at 15,00 on Saturdays and at 10,00 and 11,00 on Sundays. This is caused by the scheduling of the play on Saturday. On BBC Radio 2, the pips are used at 07,00,08,00,17,00 and 19,00 on weekdays, at 07,00 and 08,00 on Saturdays and at 08,00 and 09,00 on Sundays. The pips were used on Radio 1 during The Chris Moyles Show at 06,30 just after the news,09,00 as part of the Tedious Link feature,10 am and often before Newsbeat. As most stations only air the pips on the hour, The Chris Moyles Show was the show where the pips were broadcast on the half-hour. The pips are used at 19,00 on Saturday evenings at the start of Radio 1s 12-hour simulcast with digital station BBC Radio 1Xtra. BBC Radio 3 and BBC Radio Five Live do not currently feature the Greenwich Time Signal in their scheduled programming, the BBC World Service broadcasts the pips every hour. Pips can also be heard on many BBC Local Radio stations although their use is up to the discretion of individual stations, in 1999, pip-like sounds were incorporated into the themes written by composer David Lowe to introduce BBC Television News programmes. They are still used today on BBC One, BBC World News, the BBC does not allow the pips to be broadcast except as a time signal
33.
WWVB
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WWVB is a time signal radio station near Fort Collins, Colorado and is operated by the National Institute of Standards and Technology. Most radio-controlled clocks in North America use WWVBs transmissions to set the correct time. A single complete frame of time begins at the start of each minute, lasts one minute, and conveys the year, day of year, hour, minute. WWVB is co-located with WWV, an older time signal station that broadcasts on multiple short wave frequencies. While most time signals encode the time of the broadcasting nation. Radio-controlled clocks can then apply time zone and daylight saving time offsets as needed to local time. The time used in the broadcast is set by the NIST Time Scale and this time scale is the calculated average time of an ensemble of master clocks, themselves calibrated by the NIST-F1 and NIST-F2 cesium fountain atomic clocks. In 2011, NIST estimated the number of clocks and wristwatches equipped with a WWVB receiver at over 50 million. LF and VLF broadcasts have long used to distribute time. As early as 1904, the United States Naval Observatory was broadcasting time signals from the city of Boston as an aid to navigation and this experiment and others like it made it evident that LF and VLF signals could cover a large area using a relatively small amount of power. By 1923, NIST radio station WWV had begun broadcasting standard carrier signals to the public on frequencies ranging from 75 to 2,000 kHz and these signals were used to calibrate radio equipment, which became increasingly important as more and more stations became operational. Over the years, many radio navigation systems were designed using stable time, the most well-known of these navigation systems is LORAN-C, which allows ships and planes to navigate via reception of 100 kHz signals broadcast from multiple transmitters. What is now WWVB began as radio station KK2XEI in July 1956, the transmitter was located in Boulder, Colorado, and the effective radiated power was just 1.4 watts. Even so, the signal was able to be monitored at Harvard University in Massachusetts, the purpose of this experimental transmission was to show that the radio path was stable and the frequency error was small at low frequencies. In 1962, NIST began building a new facility at a site near Fort Collins and this site became the home of WWVB and WWVL, a 20 kHz transmitter that was moved from the mountains west of Boulder. The site was attractive for several reasons, one being its exceptionally high ground conductivity, which was due to the high alkalinity of the soil. It was also close to Boulder, which made it easy to staff and manage, but much farther away from the mountains. WWVB went on the air on July 5,1963, broadcasting a 5 kW ERP signal on 60 kHz
34.
DCF77
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DCF77 is a German longwave time signal and standard-frequency radio station. It started service as a station on 1 January 1959. In June 1973 date and time information was added and its primary and backup transmitter are located at 50°0′56″N 9°00′39″E in Mainflingen, about 25 km south-east of Frankfurt am Main, Germany. The transmitter generates a power of 50 kW, of which about 30 to 35 kW can be radiated via a T-antenna. DCF77 is controlled by the Physikalisch-Technische Bundesanstalt, Germanys national physics laboratory and it is operated by Media Broadcast GmbH, on behalf of the PTB. With Media Broadcast GmbH, a temporal transmission availability of at least 99. 7% per year or under 26.28 hours of annual downtime has been agreed upon, most service interruptions are short-term disconnections of under two minutes. Longer lasting transmission service interruptions are generally caused by strong winds and this manifests itself in electrical detuning of the antenna resonance circuit and hence a measurable phase modulation of the received signal. When the maladjustment is too large, the transmitter is temporarily out of service. In the year 2002 almost 99. 95% availability or just over 4.38 hours of downtime was realized, the timestamp sent is either in Coordinated Universal Time +1 or UTC+2 depending on daylight saving time. The highly accurate 77.5 kHz carrier signal is generated from local atomic clocks that are linked with the German master clocks at the PTB in Braunschweig, the DCF77 time signal is used for the dissemination of the German national legal time to the public. Radio clocks and watches have been popular in Europe since the late 1980s and, in mainland Europe. The DCF77 station signal carries an amplitude-modulated, pulse-width coded 1-bit/s data signal, the same data signal is also phase modulated onto the carrier using a 512-bit long pseudorandom sequence. The transmitted data signal is repeated every minute, since 2003,14 previously unused bits of the time code have been used for civil defence emergency signals. This is a service, aimed to one day replace the German network of civil defence sirens. Since 22 November 2006 the DCF77 transmitter uses bits 1–14 to transmit warning messages, under responsibility of the German Federal Office of Civil Protection and Disaster Assistance, warnings to the population can be transmitted using these 14 bits. As a further extension of the information content transmitted by DCF77, the forecast data is provided by and under responsibility of the Swiss company Meteo Time GmbH and is transferred in a proprietary transfer protocol. The same 14 bits are employed in a way that ensures compatibility with the protocols of the warning messages. For decoding the weather forecast data a license is required, since the bits previously reserved for the PTB are used, older radio clocks should not be affected by the weather data signal
35.
International Standard Serial Number
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An International Standard Serial Number is an eight-digit serial number used to uniquely identify a serial publication. The ISSN is especially helpful in distinguishing between serials with the same title, ISSN are used in ordering, cataloging, interlibrary loans, and other practices in connection with serial literature. The ISSN system was first drafted as an International Organization for Standardization international standard in 1971, ISO subcommittee TC 46/SC9 is responsible for maintaining the standard. When a serial with the content is published in more than one media type. For example, many serials are published both in print and electronic media, the ISSN system refers to these types as print ISSN and electronic ISSN, respectively. The format of the ISSN is an eight digit code, divided by a hyphen into two four-digit numbers, as an integer number, it can be represented by the first seven digits. The last code digit, which may be 0-9 or an X, is a check digit. Formally, the form of the ISSN code can be expressed as follows, NNNN-NNNC where N is in the set, a digit character. The ISSN of the journal Hearing Research, for example, is 0378-5955, where the final 5 is the check digit, for calculations, an upper case X in the check digit position indicates a check digit of 10. To confirm the check digit, calculate the sum of all eight digits of the ISSN multiplied by its position in the number, the modulus 11 of the sum must be 0. There is an online ISSN checker that can validate an ISSN, ISSN codes are assigned by a network of ISSN National Centres, usually located at national libraries and coordinated by the ISSN International Centre based in Paris. The International Centre is an organization created in 1974 through an agreement between UNESCO and the French government. The International Centre maintains a database of all ISSNs assigned worldwide, at the end of 2016, the ISSN Register contained records for 1,943,572 items. ISSN and ISBN codes are similar in concept, where ISBNs are assigned to individual books, an ISBN might be assigned for particular issues of a serial, in addition to the ISSN code for the serial as a whole. An ISSN, unlike the ISBN code, is an identifier associated with a serial title. For this reason a new ISSN is assigned to a serial each time it undergoes a major title change, separate ISSNs are needed for serials in different media. Thus, the print and electronic versions of a serial need separate ISSNs. Also, a CD-ROM version and a web version of a serial require different ISSNs since two different media are involved, however, the same ISSN can be used for different file formats of the same online serial
36.
Longwave
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In radio, longwave, also written as long wave or long-wave, and commonly abbreviated LW, refers to parts of the radio spectrum with relatively long wavelengths. The term is an one, dating from the early 20th century, when the radio spectrum was considered to consist of long, medium. Most modern radio systems and devices use wavelengths which would then have been considered ultra-short, in contemporary usage, the term longwave is not defined precisely, and its meaning varies across the world. Sometimes, part of the frequency band is included. The International Telecommunication Union Region 1 longwave broadcast band falls wholly within the low band of the radio spectrum. Broader definitions of longwave may extend below and/or above it, in the US, the Longwave Club of America is interested in frequencies below the AM broadcast band, i. e. all frequencies below 535 kHz. Because of their wavelength, radio waves in this frequency range can diffract over obstacles like mountain ranges and travel beyond the horizon. This mode of propagation, called ground wave, is the mode in the longwave band. 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. Non-directional beacons transmit continuously for the benefit of radio direction finders in marine and they identify themselves by a callsign in Morse code. They can occupy any frequency in the range 190–1750 kHz, in North America, they occupy 190–535 kHz. In ITU Region 1 the lower limit is 280 kHz, there are government broadcast stations in the range 40–80 kHz that transmit coded time signals to radio clocks. Radio controlled clocks receive their time calibration signals with built-in long-wave receivers, long-waves travel by groundwaves that hug the surface of the earth, unlike medium-waves and short-waves. Those higher-frequency signals do not follow the surface of the Earth beyond a few kilometers and these different propagation paths can make the time lag different for every signal received. The military of the United Kingdom, Russian Federation, United States, Germany, in North America during the 1970s, the frequencies 167,179 and 191 kHz were assigned to the short-lived Public Emergency Radio of the United States. Nowadays, in the United States, Part 15 of FCC regulations allow unlicensed use of 136 kHz and this is called Low Frequency Experimental Radio
37.
JJY
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JJY is the call sign of a low frequency time signal radio station located in Japan. The station broadcasts from two sites, one on Mount Otakadoya, near Fukushima, and the other on Mount Hagane, the Mount Otakadoya site is located at an elevation of 790 meters. It broadcasts a 50 kW signal on 40 kHz from an umbrella top-loading antenna situated 250 meters above the ground, as of March 2011 it has been powered down and evacuated due to the Fukushima I nuclear accidents. As of April 21 it is broadcasting again but is unattended by staff and it went off air again temporarily on April 25 due to lightning, but has ever since been on air. The Mount Hagane site is located at an elevation of 900 meters and it broadcasts a 50 kW signal on 60 kHz to avoid interfering with the Otakadoya site as their signals overlap. The antenna for the Hagane site is also a top loading antenna and is situated 200 meters above the ground. This site does not have a redundant 40 kHz transmitter, so cannot act as a fallback for the Mount Otakadoya site, both carrier signals contain an identical pulse-width modulated time code and are transmitted 24 hours a day. Low frequency transmissions are used to enhance accuracy and reduce the possibility of atmospheric interference, the calculated accuracy of JJYs signal is 1×10−11. Japan Standard Time is set by an atomic clock in Tokyo. This information is sent to the stations and is used to set a caesium atomic clock at each station. These clocks are housed in a controlled and electromagnetically shielded room to prevent outside interference with the clocks. The time code format is similar to that of WWVB in the United States. Similarly to WWVB or MSF the signal of JJY is used to synchronize consumer radio-controlled clocks sold throughout Japan, each station has an identical setup of equipment. A dual set of transmitters, a primary and a backup, however, it is not possible given the current design configuration for one site to act as a lower power alternate frequency backup for the other. The backups are set to take over in the event that the primary transmission system has a failure. The Time Signal Control Room generates the standard LF signal and time code that is broadcast, the Impedance Matching Room has a matching transformer to perform impedance matching between the transmitter and the antenna. Due to the power of radio frequency signals that pass through the room. On January 30,1940, the Communications Research Laboratory, began operations of JJY as a station, broadcasting at 4,7,9
