1.
Teleprinter
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A teleprinter is an electromechanical typewriter that can be used to send and receive typed messages from point to point and point-to-multipoint over various types of communications channels. They were adapted to provide an interface to early mainframe computers and minicomputers, sending typed data to the computer. Some models could also be used to create punched tape for data storage, teleprinters could use a variety of different communication media. These included a pair of wires, dedicated non-switched telephone circuits, switched networks that operated similarly to the public telephone network. A teleprinter attached to a modem could also communicate through standard switched public telephone lines and this latter configuration was often used to connect teleprinters to remote computers, particularly in time-sharing environments. Teleprinters have largely replaced by fully electronic computer terminals which usually use a computer monitor instead of a printer. Teleprinters were invented in order to send and receive messages without the need for operators trained in the use of Morse code, a system of two teleprinters, with one operator trained to use a typewriter, replaced two trained Morse code operators. The teleprinter system improved message speed and delivery time, making it possible for messages to be flashed across a country with little manual intervention, in 1835 Samuel Morse devised a recording telegraph. In 1841 Alexander Bain devised a printing telegraph, by 1846, the Morse telegraph service was operational between Washington, D. C. and New York. Royal Earl House patented his printing telegraph that same year and he linked two 28-key piano-style keyboards by wire. Each piano key represented a letter of the alphabet and when pressed caused the letter to print at the receiving end. A shift key gave each main key two optional values, a 56-character typewheel at the sending end was synchronised to coincide with a similar wheel at the receiving end. It was thus an example of a data transmission system. Houses equipment could transmit around 40 instantly readable words per minute, the printer could copy and print out up to 2,000 words per hour. This invention was first put in operation and exhibited at the Mechanics Institute in New York in 1844, landline teleprinter operations began in 1849 when a circuit was put in service between Philadelphia and New York City. In 1855, David Edward Hughes introduced a machine built on the work of Royal Earl House. Émile Baudot designed a system using a five unit code in 1874, the Baudot system was adopted in France in 1877, and later extensively in France. During 1901 Baudots code was modified by Donald Murray, prompted by his development of a typewriter-like keyboard
2.
Fax
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Fax, sometimes called telecopying or telefax, is the telephonic transmission of scanned printed material, normally to a telephone number connected to a printer or other output device. The receiving fax machine interprets the tones and reconstructs the image, early systems used direct conversions of image darkness to audio tone in a continuous or analog manner. Since the 1980s, most machines modulate the audio frequencies using a digital representation of the page which is compressed to quickly transmit areas which are all-white or all-black. Scottish inventor Alexander Bain worked on chemical mechanical fax type devices and he received British patent 9745 on May 27,1843 for his Electric Printing Telegraph. Frederick Bakewell made several improvements on Bains design and demonstrated a telefax machine, the Pantelegraph was invented by the Italian physicist Giovanni Caselli. He introduced the first commercial service between Paris and Lyon in 1865, some 11 years before the invention of the telephone. In 1880, English inventor Shelford Bidwell constructed the scanning phototelegraph that was the first telefax machine to scan any two-dimensional original, previously, photographs had been sent over the radio using this process. The Western Union Deskfax fax machine, announced in 1948, was a machine that fit comfortably on a desktop. As a designer for the Radio Corporation of America, in 1924, Richard H. Ranger invented the wireless photoradiogram, or transoceanic radio facsimile, the forerunner of today’s fax machines. A photograph of President Calvin Coolidge sent from New York to London on November 29,1924 became the first photo picture reproduced by transoceanic radio facsimile, commercial use of Ranger’s product began two years later. Also in 1924, Herbert E. Ives of AT&T Corporation transmitted and reconstructed the first color facsimile, around 1952 or so, Finch Facsimile, a highly developed machine, was described in detail in a book, it was never manufactured in quantity. By the late 1940s, radiofax receivers were sufficiently miniaturized to be fitted beneath the dashboard of Western Unions Telecar telegram delivery vehicles, in the 1960s, the United States Army transmitted the first photograph via satellite facsimile to Puerto Rico from the Deal Test Site using the Courier satellite. Radio fax is still in limited use today for transmitting weather charts, in 1964, Xerox Corporation introduced what many consider to be the first commercialized version of the modern fax machine, under the name or Long Distance Xerography. This model was superseded two years later with a unit that would set the standard for fax machines for years to come. Up until this point facsimile machines were expensive and hard to operate. In 1966, Xerox released the Magnafax Telecopiers, a smaller and this unit was far easier to operate and could be connected to any standard telephone line. This machine was capable of transmitting a letter-sized document in about six minutes, the first sub-minute, digital fax machine was developed by Dacom, which built on digital data compression technology originally developed at Lockheed for satellite communication. By the late 1970s, many companies around the world, entered the fax market, very shortly after a new wave of more compact, faster and efficient fax machines would hit the market
3.
Telegraph
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Telegraphy is the long-distance transmission of textual or symbolic messages without the physical exchange of an object bearing the message. Thus semaphore is a method of telegraphy, whereas pigeon post is not, telegraphy requires that the method used for encoding the message be known to both sender and receiver. Such methods are designed according to the limits of the medium used. The use of signals, beacons, reflected light signals. In the 19th century, the harnessing of electricity led to the invention of electrical telegraphy, the advent of radio in the early 20th century brought about radiotelegraphy and other forms of wireless telegraphy. The word telegraph was first coined by the French inventor of the Semaphore line, Claude Chappe, a telegraph is a device for transmitting and receiving messages over long distances, i. e. for telegraphy. The word telegraph alone now generally refers to an electrical telegraph, Wireless telegraphy is also known as CW, for continuous wave, as opposed to the earlier radio technique of using a spark gap. Contrary to the definition used by Chappe, Morse argued that the term telegraph can strictly be applied only to systems that transmit. This is to be distinguished from semaphore, which transmits messages. Smoke signals, for instance, are to be considered semaphore, according to Morse, telegraph dates only from 1832 when Pavel Schilling invented one of the earliest electrical telegraphs. A telegraph message sent by a telegraph operator or telegrapher using Morse code was known as a telegram. A cablegram was a sent by a submarine telegraph cable. Later, a Telex was a sent by a Telex network. A wire picture or wire photo was a picture that was sent from a remote location by a facsimile telegraph. A diplomatic telegram, also known as a cable, is the term given to a confidential communication between a diplomatic mission and the foreign ministry of its parent country. These continue to be called telegrams or cables regardless of the used for transmission. Commercial electrical telegraphs were introduced from 1837, the first telegraphs came in the form of optical telegraph, including the use of smoke signals, beacons, or reflected light, which have existed since ancient times. Early proposals for a telegraph system were made to the Royal Society by Robert Hooke in 1684 and were first implemented on an experimental level by Sir Richard Lovell Edgeworth in 1767
4.
Digital signal
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A digital signal is a signal that is constructed from a discrete set of waveforms of a physical quantity so as to represent a sequence of discrete values. A logic signal is a signal with only two possible values, and describes an arbitrary bit stream. Other types of signals can represent three-valued logic or higher valued logics. Alternatively, a signal may be considered to be the sequence of codes represented by such a physical quantity. Digital signals are present in all digital electronics, notably computing equipment, with digital signals, system noise, provided it is not too great, will not affect system operation whereas noise always degrades the operation of analog signals to some degree. A special case is a signal or a binary signal. In digital signal processing, a signal is a representation of a physical signal that is a sampled and quantified. A digital signal is an abstraction which is discrete in time, the signals value only exists at regular time intervals, since only the values of the corresponding physical signal at those sampled moments are significant for further digital processing. The digital signal is a sequence of codes drawn from a set of values. The digital signal may be stored, processed or transmitted physically as a pulse code modulation signal, in digital communications, a digital signal is a continuous-time physical signal, alternating between a discrete number of waveforms, representing a bit stream message. The clock signal is a digital signal that is used to synchronize many digital circuits. The image shown can be considered the waveform of a clock signal, logic changes are triggered either by the rising edge or the falling edge. The given diagram is an example of the pulse and therefore we have introduced two new terms that are, Rising edge, the transition from a low voltage to a high voltage. Falling edge, the transition from a voltage to a low one. This means that during a short, finite transition time the output may not properly reflect the input, the two states of a wire are usually represented by some measurement of an electrical property, Voltage is the most common, but current is used in some logic families. A threshold is designed for each logic family, when below that threshold, the signal is low, when above high. To create a signal, an analog signal must be modulated with a control signal to produce it. As we have seen, the simplest modulation, a type of unipolar line coding is simply to switch on and off a DC signal, so that high voltages are a 1
5.
Telephone
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A telephone, or phone, is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be heard directly. In 1876, Scottish emigrant Alexander Graham Bell was the first to be granted a United States patent for a device that produced clearly intelligible replication of the human voice and this instrument was further developed by many others. The telephone was the first device in history that people to talk directly with each other across large distances. Telephones rapidly became indispensable to businesses, government, and households, the essential elements of a telephone are a microphone to speak into and an earphone which reproduces the voice in a distant location. Until approximately the 1970s most telephones used a dial, which was superseded by the modern DTMF push-button dial. The receiver and transmitter are usually built into a handset which is held up to the ear, the dial may be located either on the handset, or on a base unit to which the handset is connected. The transmitter converts the sound waves to electrical signals which are sent through the network to the receiving phone. The receiving telephone converts the signals into audible sound in the receiver, telephones permit duplex communication, meaning they allow the people on both ends to talk simultaneously. The first telephones were connected to each other from one customers office or residence to another customers location. Being impractical beyond just a few customers, these systems were replaced by manually operated centrally located switchboards. For greater mobility, various systems were developed for transmission between mobile stations on ships and automobiles in the middle 20th century. Hand-held mobile phone]s was introduced for personal service starting in 1973, by the late 1970s several mobile telephone networks operated around the world. In 1983, the Advanced Mobile Phone System was launched, offering a standardized technology providing portability for users far beyond the residence or office. These analog cellular system evolved into digital networks with better security, greater capacity, better regional coverage, the public switched telephone network, with its hierarchical system of many switching centers, interconnects telephones around the world for communication with each other. With the standardized international numbering system, E.164, each line has an identifying telephone number. Although originally designed for voice communications, convergence has enabled most modern cell phones to have many additional capabilities. Since 1999, the trend for mobile phones is smartphones that integrate all mobile communication, a traditional landline telephone system, also known as plain old telephone service, commonly carries both control and audio signals on the same twisted pair of insulated wires, the telephone line. The control and signaling equipment consists of three components, the ringer, the hookswitch, and a dial, the ringer, or beeper, light or other device, alerts the user to incoming calls
6.
International Telecommunication Union
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ITU, based in Geneva, Switzerland, is a member of the United Nations Development Group. ITU has been an intergovernmental public-private partnership organization since its inception, ITU was formed in 1865, in Paris, at the International Telegraph Convention, this makes it one of the oldest intergovernmental organizations in the world. ITU became a United Nations specialized agency in 1947, the ITU comprises three sectors, each managing a different aspect of the matters handled by the Union, as well as ITU Telecom. The sectors were created during the restructuring of ITU at its 1992 Plenipotentiary Conference, radiocommunication Established in 1927 as the International Radio Consultative Committee or CCIR, this sector manages the international radio-frequency spectrum and satellite orbit resources. In 1992, the CCIR became the ITU-R, Standardization Standardization was the original purpose of ITU since its inception. Established in 1956 as the International Telephone and Telegraph Consultative Committee or CCITT, in 1993, the CCITT became the ITU-T. Development Established in 1992, this sector helps spread equitable, sustainable and affordable access to information and communication technologies, ITU Telecom ITU Telecom organizes major events for the worlds ICT community. A permanent General Secretariat, headed by the Secretary General, manages the work of the Union. The basic texts of the ITU are adopted by the ITU Plenipotentiary Conference, the ITU is headed by a Secretary-General, who is elected to a four-year term by the member states at the ITU Plenipotentiary Conference. On 23 October 2014 Houlin Zhao was elected 19th Secretary-General of the ITU at the Plenipotentiary Conference in Busan and his four-year mandate started on 1 January 2015, and he was formally inaugurated on 15 January 2015. There are 193 Member States of the ITU, which are all UN member states, the most recent member state to join the ITU is South Sudan, which became a member on 14 July 2011. The Republic of China was blocked from membership by the Peoples Republic of China, palestine was admitted as an observer in 2010. The Summit was held as two conferences in 2003 and 2005 in Geneva and Tunis, respectively, with the aim of bridging the digital divide, in December 2012, the ITU facilitated The World Conference on International Telecommunications 2012 in Dubai. WCIT-12 was a conference to address International Telecommunications Regulations, the international rules for telecommunications. The previous conference to update the Regulations was held in Melbourne in 1988, in August 2012, ITU called for a public consultation on a draft document ahead of the conference. Telecommunications ministers from 193 countries attended the conference in Dubai, the current regulatory structure was based on voice telecommunications, when the Internet was still in its infancy. In 1988, telecommunications operated under regulated monopolies in most countries, as the Internet has grown, organizations such as ICANN have come into existence to manage key resources such as Internet addresses and Domain Names. Some outside the United States believe that the United States exerts too much influence over the governance of the Internet, current proposals look to take into account the prevalence of data communications
7.
Paper tape
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Punched tape or perforated paper tape is a form of data storage, consisting of a long strip of paper in which holes are punched to store data. Paper tapes constructed from punched cards were used throughout the 19th century for controlling looms. Perforated paper tapes were first used by Basile Bouchon in 1725 to control looms, however, the paper tapes were expensive to create, fragile, and difficult to repair. By 1801 Joseph Marie Jacquard had developed machines to paper tapes by tying punched cards in a sequence. The resulting paper tape, also called a chain of cards, was stronger and simpler both to create and to repair and this led to the concept of communicating data not as a stream of individual cards, but one continuous card, or a tape. In 1846, Alexander Bain used punched tape to send telegrams, in 1880s, Tolbert Lanston invented a Monotype System, which consisted of a keyboard and a composition caster. The tape, punched with the keyboard, was read by the caster. The tape reader used compressed air, which passed through the holes and was directed into certain mechanisms of the caster, the system went into commercial use in 1897 and was in production well into 1970s, undergoing several changes along the way. Data were represented by the presence or absence of a hole at a particular location, tapes originally had five rows of holes for data. Later tapes had 6,7 and 8 rows, an early electro-mechanical calculating machine, the Automatic Sequence Controlled Calculator or Harvard Mark I, used paper tape with 24 rows. A row of smaller sprocket holes that were always punched served to feed the tape, later optical readers used the sprocket holes to generate timing pulses. The sprocket holes are a bit to one side, making it clear which way to orient the tape in the reader, text was encoded in several ways. The earliest standard character encoding was Baudot, which dates back to the century and had 5 holes. The Baudot code was never used in teleprinters, instead, modifications such as the Murray code, Western Union code, International Telegraph Alphabet No. 2, and American Teletypewriter code, were used, other standards, such as Teletypesetter, FIELDATA and Flexowriter, had 6 holes. In the early 1960s, the American Standards Association led a project to develop a code for data processing. This 7-level code was adopted by some users, including AT&T. Others, such as Telex. Tape for punching was 0.00394 inches thick, the two most common widths were 11/16 inch for five bit codes, and 1 inch for tapes with six or more bits
8.
Baudot code
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The Baudot code, invented by Émile Baudot, is a character set predating EBCDIC and ASCII. It was the predecessor to the International Telegraph Alphabet No,2, the teleprinter code in use until the advent of ASCII. Each character in the alphabet is represented by a series of bits, the symbol rate measurement is known as baud, and is derived from the same name. Technically, five-bit codes began in the 16th century, when Francis Bacon developed the now called Bacons cipher. However, this cipher is not a cipher and as such is not readily suitable for telecommunications. Baudot invented his original code in 1870 and patented it in 1874 and it was a 5-bit code, with equal on and off intervals, which allowed telegraph transmission of the Roman alphabet and punctuation and control signals. It was based on an earlier code developed by Carl Friedrich Gauss and it was a Gray code, nonetheless, the code by itself was not patented because French patent law does not allow concepts to be patented. Baudots original code was adapted to be sent from a manual keyboard, the code was entered on a keyboard which had just five piano type keys, operated with two fingers of the left hand and three fingers of the right hand. Operators had to maintain a rhythm, and the usual speed of operation was 30 words per minute. The table on the shows the allocation of the Baudot code which was employed in the British Post Office for continental. It will be observed that a number of characters in the code are replaced by fractionals in the inland code. Code elements 1,2 and 3 are transmitted by keys 1,2 and 3, code elements 4 and 5 are transmitted by keys 4 and 5, and these are operated by the first two fingers of the left hand. Baudots code became known as International Telegraph Alphabet No,1, and is no longer used. In 1901, Baudots code was modified by Donald Murray, prompted by his development of a typewriter-like keyboard. The Murray system employed an intermediate step, a keyboard perforator, which allowed an operator to punch a tape. At the receiving end of the line, a mechanism would print on a paper tape. For example, the letters are E and T. The ten two-hole letters are AOINSHRDLZ, very similar to the Etaoin shrdlu order used in Linotype machines, ten more letters have three holes, and the four-hole letters are VXKQ
9.
BT Group
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BT Group plc is a holding company which owns British Telecommunications plc, a British multinational telecommunications services company with head offices in London, United Kingdom. It has operations in around 180 countries, BTs origins date back to the founding of the Electric Telegraph Company in 1846 which developed a nationwide communications network. In 1912, the General Post Office, a government department, the Post Office Act of 1969 led to the GPO becoming a public corporation. British Telecommunications, trading as British Telecom, was formed in 1980, British Telecommunications was privatised in 1984, becoming British Telecommunications plc, with some 50 percent of its shares sold to investors. The Government sold its stake in further share sales in 1991 and 1993. BT has a listing on the London Stock Exchange, a secondary listing on the New York Stock Exchange. BT controls a number of large subsidiaries, BT announced in February 2015 that it had agreed to acquire EE for £12.5 billion, and received final regulatory approval from the Competition and Markets Authority on 15 January 2016. The transaction was completed on 29 January 2016, BTs origins date back to the establishment of the first telecommunications companies in Britain. Among them was the first commercial service, the Electric Telegraph Company. As these companies amalgamated and were taken over or collapsed, the companies were transferred to state control under the Post Office in 1912. These companies were merged and rebranded as British Telecom, in January 1878 Alexander Graham Bell demonstrated his recently developed telephone to Queen Victoria at Osborne House on the Isle of Wight. John Hudson, with his premises in nearby Shudehill. As the number of installed telephones across the country grew it became sensible to consider constructing telephone exchanges to allow all the telephones in each city to be connected together, the first exchange was opened in London in August 1879, closely followed by the Lancashire Telephonic Exchange in Manchester. From 1878, the service in Britain was provided by private sector companies such as the National Telephone Company. In 1896, the National Telephone Company was taken over by the General Post Office, in 1912 it became the primary supplier of telecommunications services, after the Post Office took over the private sector telephone service in GB, except for a few local authority services. Those services all folded within a few years, the exception being Kingston upon Hull. Converting the Post Office into an industry, as opposed to a governmental department, was first discussed in 1932 by Lord Wolmer. In 1932 the Bridgeman Committee produced a report that was rejected, in 1961, more proposals were ignored
10.
Reichspost
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Reichspost was the name of several postal authorities in Germany. It may refer to one of these entities, The Imperial Reichspost was the name of the postal service of the Holy Roman Empire. The Bergamascan Tasso family had built up postal routes throughout Italy since c. 1290, Ruggiero had already connected Vienna and Innsbruck with Italy, Styria, and Brussels, before Maximilian expanded from those routes throughout his realm. Charles V confirmed Jannettos son Giovanni Battista as Postmaster General in 1520, confirmed by Emperor Rudolph II in 1595, the Imperial postal service remained a monopoly of the Thurn und Taxis family until it was terminated with the end of the Empire in 1806. The Imperial Reichspost was based in Brussels in the Spanish Netherlands, from where the route led via Namur, Bastogne, Lieser, Wöllstein, Rheinhausen. It was also used to bypass the Kingdom of France in order to keep in touch with Habsburg Spain during times of hostility, competing services were prohibited, although the Imperial cities were permitted to maintain their own communication system. In the course of the War of the Spanish Succession, the Thurn und Taxis seat was relocated from Brussels to the Free City of Frankfurt in 1702, two years later, the postal authority moved to Regensburg, seat of the Imperial Diet. The family had accumulated wealth, nonetheless, it was devastated by the Napoleonic Wars. Originally a military alliance, it evolved to a federation with the issuing of a constitution with effect from 1 July 1867. In the course of the war, Prussian troops had occupied the Free City of Frankfurt, according to article 48, the federal area of the Northern German states, de facto an enlarged Prussia, came under the united postal authority, led by director Heinrich von Stephan. Its official name was Kaiserliche Post und Telegraphenverwaltung, the Southern German federated states of Baden, Württemberg and Bavaria initially maintained separate state post authorities, that nevertheless were integrated into the nationwide administration. On 1 January 1876 a Reichspostamt under Postmaster General von Stephan was split off Bismarcks Reich Chancellery as a government agency in its own right. In the First World War, a Reichsabgabe tax was levied on the traffic from 1 August 1916 in order to finance the war expenses. With the establishment of the Weimar Republic upon the German Revolution of 1918–1919, after the hyperinflation period, the Deutsche Reichspost agency was again spun off in 1924 and operated as a state-owned enterprise. It was during this time that the Reichspost installed the first public Videophone, in 1941 postal codes were introduced. Deliveries were more and more affected by the advance of Allied troops from January 1945 on, the Reichspost finally ceased to function with the German Instrument of Surrender on May 8. The Reichspost was initially replaced by Allied-controlled postal authorities that provided services in the occupation zones. From 1947 a united agency served the British-American Bizone area, with the emergence of two German states, the Deutsche Bundespost was established in West Germany, and the Deutsche Post in East Germany
11.
West Germany
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West Germany is the common English name for the Federal Republic of Germany or FRG in the period between its creation on 23 May 1949 to German reunification on 3 October 1990. During this Cold War era, NATO-aligned West Germany and Warsaw Pact-aligned East Germany were divided by the Inner German border, after 1961 West Berlin was physically separated from East Berlin as well as from East Germany by the Berlin Wall. This situation ended when East Germany was dissolved and its five states joined the ten states of the Federal Republic of Germany along with the reunified city-state of Berlin. With the reunification of West and East Germany, the Federal Republic of Germany, enlarged now to sixteen states and this period is referred to as the Bonn Republic by historians, alluding to the interwar Weimar Republic and the post-reunification Berlin Republic. The Federal Republic of Germany was established from eleven states formed in the three Allied Zones of occupation held by the United States, the United Kingdom and France, US and British forces remained in the country throughout the Cold War. Its population grew from roughly 51 million in 1950 to more than 63 million in 1990, the city of Bonn was its de facto capital city. The fourth Allied occupation zone was held by the Soviet Union, as a result, West Germany had a territory about half the size of the interbellum democratic Weimar Republic. At the onset of the Cold War, Europe was divided among the Western and Eastern blocs, Germany was de facto divided into two countries and two special territories, the Saarland and divided Berlin. The Federal Republic of Germany claimed a mandate for all of Germany. It took the line that the GDR was an illegally constituted puppet state, though the GDR did hold regular elections, these were not free and fair. For all practical purposes the GDR was a Soviet puppet state, from the West German perspective the GDR was therefore illegitimate. Three southwestern states of West Germany merged to form Baden-Württemberg in 1952, in addition to the resulting ten states, West Berlin was considered an unofficial de facto 11th state. It recognised the GDR as a de facto government within a single German nation that in turn was represented de jure by the West German state alone. From 1973 onward, East Germany recognised the existence of two German countries de jure, and the West as both de facto and de jure foreign country, the Federal Republic and the GDR agreed that neither of them could speak in the name of the other. The first chancellor Konrad Adenauer, who remained in office until 1963, had worked for an alignment with NATO rather than neutrality. He not only secured a membership in NATO but was also a proponent of agreements that developed into the present-day European Union, when the G6 was established in 1975, there was no question whether the Federal Republic of Germany would be a member as well. With the collapse of communism in Central and Eastern Europe in 1989, symbolised by the opening of the Berlin Wall, East Germany voted to dissolve itself and accede to the Federal Republic in 1990. Its five post-war states were reconstituted along with the reunited Berlin and they formally joined the Federal Republic on 3 October 1990, raising the number of states from 10 to 16, ending the division of Germany
12.
West Berlin
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West Berlin was an enclave which comprised the western part of the city of Berlin during the Cold War. It was formally controlled by the Western Allies and formed a de facto part of West Germany, and was entirely surrounded by the Soviet-controlled East Berlin and East Germany. West Berlin had great significance during the Cold War, as it was widely considered by westerners as an island of freedom. A wealthy city, West Berlin was noted for its liberal and cosmopolitan character. With about two million inhabitants, West Berlin had the biggest population of any city in Cold War Germany and it was 100 miles east of the Inner German border and only accessible by land from West Germany by narrow rail and highway corridors. It consisted of the American, British, and French occupation sectors established in 1945 and was de facto part of West Germany and it had a special and unique legal status because its administration was formally conducted by the Western Allies. East Berlin, de jure occupied and administered by the Soviet Union, was the de facto capital of East Germany, the Berlin Wall, built in 1961, physically divided West Berlin from its East German surroundings until it fell in 1989. The Potsdam Agreement established the framework for the occupation of Germany in the wake of World War II. The territory of Germany, as it existed in 1937, would be reduced by most of Eastern Germany thus creating the former territories of Germany. The remaining territory would be divided into four zones, each administered by one of the allied countries, according to the agreement, the occupation of Berlin would end only as a result of a quadripartite agreement. The Western Allies were guaranteed three air corridors to their sectors of Berlin, and the Soviets also informally allowed road, at first, this arrangement was intended to be only a temporary administrative structure, with all parties declaring that Germany and Berlin would soon be reunited. However, as the relations between the allies and the Soviet Union soured and the Cold War began, the joint administration of Germany. Soon, Soviet-occupied Berlin and western-occupied Berlin had separate city administrations, in 1948, the Soviets tried to force the Western Allies out of Berlin by imposing a land blockade on the western sectors—the Berlin Blockade. The West responded by using its air corridors for supplying their part of the city with food, in May 1949, the Soviets lifted the blockade, and West Berlin as a separate city with its own jurisdiction was maintained. Following the Berlin Blockade, normal contacts between East and West Berlin resumed, however, in cases this proved only temporary. In 1952, the East German government began sealing its borders, as a direct result the electrical grids were separated and phone lines were cut. However, the culmination of the schism did not occur until 1961 with the construction of the Berlin Wall. From the legal theory followed by the Western Allies, the occupation of most of Germany ended in 1949 with the declaration of the Federal Republic of Germany and the German Democratic Republic
13.
Africa
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Africa is the worlds second-largest and second-most-populous continent. At about 30.3 million km² including adjacent islands, it covers 6% of Earths total surface area and 20.4 % of its land area. With 1.2 billion people as of 2016, it accounts for about 16% of the human population. The continent includes Madagascar and various archipelagos and it contains 54 fully recognized sovereign states, nine territories and two de facto independent states with limited or no recognition. Africas population is the youngest amongst all the continents, the age in 2012 was 19.7. Algeria is Africas largest country by area, and Nigeria by population, afarensis, Homo erectus, H. habilis and H. ergaster – with the earliest Homo sapiens found in Ethiopia being dated to circa 200,000 years ago. Africa straddles the equator and encompasses numerous climate areas, it is the continent to stretch from the northern temperate to southern temperate zones. Africa hosts a diversity of ethnicities, cultures and languages. In the late 19th century European countries colonized most of Africa, Africa also varies greatly with regard to environments, economics, historical ties and government systems. However, most present states in Africa originate from a process of decolonization in the 20th century, afri was a Latin name used to refer to the inhabitants of Africa, which in its widest sense referred to all lands south of the Mediterranean. This name seems to have referred to a native Libyan tribe. The name is connected with Hebrew or Phoenician ʿafar dust. The same word may be found in the name of the Banu Ifran from Algeria and Tripolitania, under Roman rule, Carthage became the capital of the province of Africa Proconsularis, which also included the coastal part of modern Libya. The Latin suffix -ica can sometimes be used to denote a land, the later Muslim kingdom of Ifriqiya, modern-day Tunisia, also preserved a form of the name. According to the Romans, Africa lay to the west of Egypt, while Asia was used to refer to Anatolia, as Europeans came to understand the real extent of the continent, the idea of Africa expanded with their knowledge. 25,4, whose descendants, he claimed, had invaded Libya, isidore of Seville in Etymologiae XIV.5.2. Suggests Africa comes from the Latin aprica, meaning sunny, massey, in 1881, stated that Africa is derived from the Egyptian af-rui-ka, meaning to turn toward the opening of the Ka. The Ka is the double of every person and the opening of the Ka refers to a womb or birthplace
14.
Asia
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Asia covers an area of 44,579,000 square kilometres, about 30% of Earths total land area and 8. 7% of the Earths total surface area. The continent, which has long been home to the majority of the population, was the site of many of the first civilizations. Asia is notable for not only its large size and population. In general terms, Asia is bounded on the east by the Pacific Ocean, on the south by the Indian Ocean, the western boundary with Europe is a historical and cultural construct, as there is no clear physical and geographical separation between them. The most commonly accepted boundaries place Asia to the east of the Suez Canal, the Ural River, and the Ural Mountains, and south of the Caucasus Mountains, China and India alternated in being the largest economies in the world from 1 to 1800 A. D. The accidental discovery of America by Columbus in search for India demonstrates this deep fascination, the Silk Road became the main East-West trading route in the Asian hitherland while the Straits of Malacca stood as a major sea route. Asia has exhibited economic dynamism as well as robust population growth during the 20th century, given its size and diversity, the concept of Asia—a name dating back to classical antiquity—may actually have more to do with human geography than physical geography. Asia varies greatly across and within its regions with regard to ethnic groups, cultures, environments, economics, historical ties, the boundary between Asia and Africa is the Red Sea, the Gulf of Suez, and the Suez Canal. This makes Egypt a transcontinental country, with the Sinai peninsula in Asia, the border between Asia and Europe was historically defined by European academics. In Sweden, five years after Peters death, in 1730 Philip Johan von Strahlenberg published a new atlas proposing the Urals as the border of Asia, the Russians were enthusiastic about the concept, which allowed them to keep their European identity in geography. Tatishchev announced that he had proposed the idea to von Strahlenberg, the latter had suggested the Emba River as the lower boundary. Over the next century various proposals were made until the Ural River prevailed in the mid-19th century, the border had been moved perforce from the Black Sea to the Caspian Sea into which the Ural River projects. The border between the Black Sea and the Caspian is usually placed along the crest of the Caucasus Mountains, the border between Asia and the loosely defined region of Oceania is usually placed somewhere in the Malay Archipelago. The terms Southeast Asia and Oceania, devised in the 19th century, have had several different geographic meanings since their inception. The chief factor in determining which islands of the Malay Archipelago are Asian has been the location of the possessions of the various empires there. Lewis and Wigen assert, The narrowing of Southeast Asia to its present boundaries was thus a gradual process, Asia is larger and more culturally diverse than Europe. It does not exactly correspond to the borders of its various types of constituents. From the time of Herodotus a minority of geographers have rejected the three-continent system on the grounds there is no or is no substantial physical separation between them
15.
Shortwave radio
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Shortwave radio is radio transmission using shortwave frequencies, generally 1. 6–30 MHz, just above the medium wave AM broadcast band. Radio waves in this band can be reflected or refracted from a layer of charged atoms in the atmosphere called the ionosphere. Therefore, short waves directed at an angle into the sky can be reflected back to Earth at great distances and this is called skywave or skip propagation. Shortwave radio is used for broadcasting of voice and music to listeners over very large areas. It is also used for military radar, diplomatic communication. The widest popular definition of the frequency interval is the ITU Region 1 definition, and is the span 1. 6–30 MHz, just above the medium wave band. In reality, the definition of the frequency band is a mess. The broadcast medium wave band now extends above the 200 m/1500 kHz limit, early radio telegraphy had used long wave transmissions. The drawbacks to this included a very limited spectrum available for long distance communication. It was also difficult to beam the radio wave directionally with long wave, prior to the 1920s, the shortwave frequencies above 1.5 MHz were regarded as useless for long distance communication and were designated in many countries for amateur use. Franklin rigged up an antenna at Poldhu Wireless Station, Cornwall. In June and July 1923, wireless transmissions were completed during nights on 97 meters from Poldhu to Marconis yacht Elettra in the Cape Verde Islands, in September 1924, Marconi transmitted daytime and nighttime on 32 meters from Poldhu to his yacht in Beirut. Franklin went on to refine the directional transmission, by inventing the curtain array aerial system, the UK-to-Canada shortwave Beam Wireless Service went into commercial operation on 25 October 1926. Beam Wireless Services from the UK to Australia, South Africa, Shortwave communications began to grow rapidly in the 1920s, similar to the internet in the late 20th century. Shortwave also ended the need for investments in massive longwave wireless stations. The cable companies began to lose large sums of money in 1927, the British government convened the Imperial Wireless and Cable Conference in 1928 to examine the situation that had arisen as a result of the competition of Beam Wireless with the Cable Services. The name of the company was changed to Cable and Wireless Ltd. in 1934, long-distance cables had a resurgence beginning in 1956 with the laying of TAT-1 across the Atlantic Ocean, the first voice frequency cable on this route. This provided 36 high quality telephone channels and was followed by even higher capacity cables all around the world
16.
Time-division multiplexing
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It is used when the data rate of the transmission medium exceeds that of signal to be transmitted. Time-division multiplexing was first developed for applications in telegraphy to route multiple transmissions simultaneously over a transmission line. In the 1870s, Émile Baudot developed a system of multiple Hughes telegraph machines. The communication was by a microwave system throughout Long Island, the experimental TDM system was developed by RCA Laboratories between 1950 and 1953. In 1962, engineers from Bell Labs developed the first D1 channel banks, a channel bank sliced a 1.544 Mbit/s digital signal into 8,000 separate frames, each composed of 24 contiguous bytes. Each byte represented a single telephone call encoded into a constant bit rate signal of 64 kbit/s, channel banks used the fixed position of one byte in the frame to identify the call it belonged to. The time domain is divided into several recurrent time slots of fixed length, a sample byte or data block of sub-channel 1 is transmitted during time slot 1, sub-channel 2 during time slot 2, etc. One TDM frame consists of one time slot per sub-channel plus a synchronization channel and sometimes error correction channel before the synchronization. After the last sub-channel, error correction, and synchronization, the cycle all over again with a new frame, starting with the second sample, byte or data block from sub-channel 1. The Basic Rate Interface and Primary Rate Interface for the Integrated Services Digital Network, TDM allows transmitting and receiving telephone switches to create channels within a transmission stream. A standard DS0 voice signal has a bit rate of 64 kbit/s. A TDM circuit runs at a higher signal bandwidth, permitting the bandwidth to be divided into time frames for each voice signal which is multiplexed onto the line by the transmitter. If the TDM frame consists of n voice frames, the bandwidth is n*64 kbit/s. Each voice time slot in the TDM frame is called a channel, in European systems, standard TDM frames contain 30 digital voice channels, and in American systems, they contain 24 channels. Both standards also contain extra bits for signaling and synchronization bits, multiplexing more than 24 or 30 digital voice channels is called higher order multiplexing. Higher order multiplexing is accomplished by multiplexing the standard TDM frames, for example, a European 120 channel TDM frame is formed by multiplexing four standard 30 channel TDM frames. At each higher order multiplex, four TDM frames from the lower order are combined, creating multiplexes with a bandwidth of n*64 kbit/s. There are three types of synchronous TDM, T1, SONET/SDH, and ISDN, plesiochronous digital hierarchy was developed as a standard for multiplexing higher order frames
17.
Amateur radio
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The amateur radio service is established by the International Telecommunication Union through the International Telecommunication Regulations. National governments regulate technical and operational characteristics of transmissions and issue individual stations licenses with a call sign. Prospective amateur operators are tested for their understanding of key concepts in electronics, according to an estimate made in 2011 by the American Radio Relay League, two million people throughout the world are regularly involved with amateur radio. About 830,000 amateur radio stations are located in IARU Region 2 followed by IARU Region 3 with about 750,000 stations, a significantly smaller number, about 400,000, are located in IARU Region 1. The origins of amateur radio can be traced to the late 19th century, the First Annual Official Wireless Blue Book of the Wireless Association of America, produced in 1909, contains a list of amateur radio stations. This radio callbook lists wireless telegraph stations in Canada and the United States, as with radio in general, amateur radio was associated with various amateur experimenters and hobbyists. Amateur radio enthusiasts have significantly contributed to science, engineering, industry, research by amateur operators has founded new industries, built economies, empowered nations, and saved lives in times of emergency. Ham radio can also be used in the classroom to teach English, map skills, geography, math, science, the term ham radio was first a pejorative that mocked amateur radio operators with a 19th-century term for being bad at something, like ham-fisted or ham actor. It had already used for bad wired telegraph operators. Subsequently, the community adopted it as a moniker, much like the Know-Nothing Party, or other groups. Other, more entertaining explanations have grown up throughout the years, the many facets of amateur radio attract practitioners with a wide range of interests. Many amateurs begin with a fascination of radio communication and then combine other personal interests to make pursuit of the hobby rewarding, some of the focal areas amateurs pursue include radio contesting, radio propagation study, public service communication, technical experimentation, and computer networking. Amateur radio operators use various modes of transmission to communicate, the two most common modes for voice transmissions are frequency modulation and single sideband. FM offers high quality audio signals, while SSB is better at long distance communication when bandwidth is restricted. Radiotelegraphy using Morse code, also known as CW from continuous wave, is the extension of landline telegraphy developed by Samuel Morse. Morse, using internationally agreed message encodings such as the Q code, a similar legacy mode popular with home constructors is amplitude modulation, pursued by many vintage amateur radio enthusiasts and aficionados of vacuum tube technology. Demonstrating a proficiency in Morse code was for years a requirement to obtain an amateur license to transmit on frequencies below 30 MHz. Following changes in regulations in 2003, countries are no longer required to demand proficiency
18.
Radioteletype
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Radioteletype is a telecommunications system consisting originally of two or more electromechanical teleprinters in different locations connected by radio rather than a wired link. These machines were later superseded by personal computers running software to emulate teleprinters, Radioteletype evolved from earlier landline teleprinter operations that began in the mid-1800s. The US Navy Department successfully tested printing telegraphy between an airplane and ground station in 1922. Later that year, the Radio Corporation of America successfully tested printing telegraphy via their Chatham, Massachusetts, commercial RTTY systems were in active service between San Francisco and Honolulu as early as April 1932 and between San Francisco and New York City by 1934. The US military used radioteletype in the 1930s and expanded this usage during World War II, from the 1980s, teleprinters were replaced by computers running teleprinter emulation software. In some applications, notably military and government, radioteletype is known by the acronym RATT, landline teleprinter operations began in 1849 when a circuit was put in service between Philadelphia and New York City. Émile Baudot designed a system using a five unit code in 1874 that is still in use today, teleprinter system design was gradually improved until, at the beginning of World War II, it represented the principal distribution method used by the news services. Radioteletype evolved from earlier landline teleprinter operations. The US Department of the Navy successfully tested printing telegraphy between an airplane and ground station in August 1922. Later that year, the Radio Corporation of America successfully tested printing telegraphy via their Chatham, an early implementation of the Radioteletype was the Watsongraph, named after Detroit inventor Glenn Watson in March 1931. Commercial RTTY systems were in service between San Francisco and Honolulu as early as April 1932 and between San Francisco and New York City by 1934. The US Military used radioteletype in the 1930s and expanded this usage during World War II, the Navy called radioteletype RATT and the Army Signal Corps called radioteletype SCRT, an abbreviation of Single-Channel Radio Teletype. The military used frequency shift keying technology and this proved very reliable even over long distances. From the 1980s, teleprinters were replaced by computers running teleprinter emulation software, a radioteletype station consists of three distinct parts, the Teletype or teleprinter, the modem and the radio. The Teletype or teleprinter is an electromechanical or electronic device, electromechanical teleprinters were heavy, complex and noisy, and have been replaced with electronic units. The teleprinter includes a keyboard, which is the means of entering text. An alternative input device is a tape reader and, more recently. Alternative output devices are tape perforators and computer storage media, the line output of a teleprinter can be at either digital logic levels or line levels
19.
Computer sound card
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A sound card is an internal expansion card that provides input and output of audio signals to and from a computer under control of computer programs. The term sound card is applied to external audio interfaces used for professional audio applications. Sound functionality can also be integrated onto the motherboard, using components similar to found on plug-in cards. The integrated sound system is still referred to as a sound card. Most sound cards use a converter, which converts recorded or generated digital data into an analog format. The output signal is connected to an amplifier, headphones, or external device using standard interconnects, multichannel digital sound playback can also be used for music synthesis, when used with a compliance, and even multiple-channel emulation. This approach has become common as manufacturers seek simpler and lower-cost sound cards, most sound cards have a line in connector for an input signal from a cassette tape or other sound source that has higher voltage levels than a microphone. The sound card digitizes this signal, the DMAC transfers the samples to the main memory, from where a recording software may write it to the hard disk for storage, editing, or further processing. Another common external connector is the connector, for signals from a microphone or other low-level input device. Input through a microphone jack can be used, for example, an important sound card characteristic is polyphony, which refers to its ability to process and output multiple independent voices or sounds simultaneously. These distinct channels are seen as the number of audio outputs, sometimes, the terms voice and channel are used interchangeably to indicate the degree of polyphony, not the output speaker configuration. For example, many older sound chips could accommodate three voices, but only one channel for output, requiring all voices to be mixed together. Later cards, such as the AdLib sound card, had a 9-voice polyphony combined in 1 mono output channel, for some years, most PC sound cards have had multiple FM synthesis voices which were usually used for MIDI music. Modern low-cost integrated soundcards such as audio codecs like those meeting the AC97 standard and this is similar to the way inexpensive softmodems perform modem tasks in software rather than in hardware. Also, in the days of wavetable sample-based synthesis, some sound card manufacturers advertised polyphony solely on the MIDI capabilities alone. In this case, the output channel is irrelevant, typically. Instead, the polyphony measurement solely applies to the number of MIDI instruments the sound card is capable of producing at one given time, the final playback stage is performed by an external DAC with significantly fewer channels than voices. Connectors on the cards are color-coded as per the PC System Design Guide
20.
Email
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Electronic mail, or email, is a method of exchanging digital messages between people using digital devices such as computers and mobile phones. Email first entered use in the 1960s and by the mid-1970s had taken the form now recognized as email. Email operates across computer networks, which today is primarily the Internet, some early email systems required the author and the recipient to both be online at the same time, in common with instant messaging. Todays email systems are based on a store-and-forward model, Email servers accept, forward, deliver, and store messages. Originally an ASCII text-only communications medium, Internet email was extended by Multipurpose Internet Mail Extensions to carry text in character sets. International email, with internationalized email addresses using UTF-8, has been standardized, the history of modern Internet email services reaches back to the early ARPANET, with standards for encoding email messages published as early as 1973. An email message sent in the early 1970s looks very similar to an email sent today. Email played an important part in creating the Internet, and the conversion from ARPANET to the Internet in the early 1980s produced the core of the current services, historically, the term electronic mail was used generically for any electronic document transmission. For example, several writers in the early 1970s used the term to describe fax document transmission, as a result, it is difficult to find the first citation for the use of the term with the more specific meaning it has today. This spelling also appears in most dictionaries, Mail was the form used in the original protocol standard, RFC524. The service is referred to as mail, and a piece of electronic mail is called a message. EMail is a form that has been used in RFCs for the Authors Address and is expressly required for historical reasons. E-mail is sometimes used, capitalizing the initial E as in similar abbreviations like E-piano, E-guitar, A-bomb, by 1968, AUTODIN linked more than 300 sites in several countries. With the introduction of MITs Compatible Time-Sharing System in 1961, multiple users could log in to a system from remote dial-up terminals. Informal methods of using this to pass messages were developed and expanded,1965 – MITs CTSS MAIL and it used the Unix mail client to send messages between system users. The concept was extended to communicate remotely over the Berkeley Network,1979 – EMAIL, an application written by Shiva Ayyadurai for the University of Medicine and Dentistry of New Jersey. 1979 – MH Message Handling System developed at RAND provided several tools for managing electronic mail on Unix, most of them only allowed communication between users logged into the same host or mainframe, although there might be hundreds or thousands of users within an organization. In the early 1980s, networked personal computers on LANs became increasingly important, server-based systems similar to the earlier mainframe systems were developed
