The mail or post is a system for physically transporting postcards , letters , and parcels . A postal service can be private or public, though many governments place restrictions on private systems. Since the mid-19th century, national postal systems have generally been established as a government monopoly , with a fee on the article prepaid. Proof of payment is usually in the form of an adhesive postage stamp , but a postage meter is also used for bulk mailing.
111-646: Telecommunication , often used in its plural form or abbreviated as telecom , is the transmission of information with an immediacy comparable to face-to-face communication. As such, slow communications technologies like postal mail and pneumatic tubes are excluded from the definition. Many transmission media have been used for telecommunications throughout history, from smoke signals , beacons , semaphore telegraphs , signal flags , and optical heliographs to wires and empty space made to carry electromagnetic signals. These paths of transmission may be divided into communication channels for multiplexing , allowing for
222-412: A thermionic tube or thermionic valve uses thermionic emission of electrons from a heated cathode for a number of fundamental electronic functions such as signal amplification and current rectification . The simplest vacuum tube, the diode invented in 1904 by John Ambrose Fleming , contains only a heated electron-emitting cathode and an anode. Electrons can only flow in one direction through
333-504: A legal monopoly . The worldwide postal system constituting the individual national postal systems of the world's self-governing states is coordinated by the Universal Postal Union , which among other things sets international postage rates, defines standards for postage stamps and operates the system of international reply coupons . In most countries a system of codes has been created (referred to as ZIP codes in
444-411: A radio broadcasting station , the station's large power amplifier is the transmitter and the broadcasting antenna is the interface between the power amplifier and the free space channel. The free space channel is the transmission medium and the receiver's antenna is the interface between the free space channel and the receiver. Next, the radio receiver is the destination of the radio signal, where it
555-408: A better price for their goods. In Côte d'Ivoire , coffee growers share mobile phones to follow hourly variations in coffee prices and sell at the best price. On the macroeconomic scale, Lars-Hendrik Röller and Leonard Waverman suggested a causal link between good telecommunication infrastructure and economic growth. Few dispute the existence of a correlation although some argue it is wrong to view
666-637: A block of dots as a two-dimensional barcode . The "block of dots" method allows for the encoding of proof of payment of postage, exact routing for delivery, and other features. The ordinary mail service was improved in the 20th century with the use of planes for a quicker delivery. The world's first scheduled airmail post service took place in the United Kingdom between the London suburbs of Hendon and Windsor, Berkshire , on 9 September 1911. Some methods of airmail proved ineffective, however, including
777-437: A caveat for it in 1876. Gray abandoned his caveat and because he did not contest Bell's priority, the examiner approved Bell's patent on March 3, 1876. Gray had filed his caveat for the variable resistance telephone, but Bell was the first to document the idea and test it in a telephone.[88] Antonio Meucci invented a device that allowed the electrical transmission of voice over a line nearly 30 years before in 1849, but his device
888-440: A connection between two or more users. For both types of networks, repeaters may be necessary to amplify or recreate the signal when it is being transmitted over long distances. This is to combat attenuation that can render the signal indistinguishable from the noise. Another advantage of digital systems over analogue is that their output is easier to store in memory, i.e., two voltage states (high and low) are easier to store than
999-494: A continuous range of states. Telecommunication has a significant social, cultural and economic impact on modern society. In 2008, estimates placed the telecommunication industry 's revenue at US$ 4.7 trillion or just under three per cent of the gross world product (official exchange rate). Several following sections discuss the impact of telecommunication on society. On the microeconomic scale, companies have used telecommunications to help build global business empires. This
1110-622: A form of meter label and thus do not need to be cancelled.) Documents should generally not be read by anyone other than the addressee; for example, in the United States of America it is a violation of federal law for anyone other than the addressee and the government to open mail. There are exceptions however: executives often assign secretaries or assistants the task of handling their mail; and postcards do not require opening and can be read by anyone. For mail contained within an envelope, there are legal provisions in some jurisdictions allowing
1221-406: A higher-frequency signal (known as the " carrier wave ") before transmission. There are several different modulation schemes available to achieve this [two of the most basic being amplitude modulation (AM) and frequency modulation (FM)]. An example of this process is a disc jockey's voice being impressed into a 96 MHz carrier wave using frequency modulation (the voice would then be received on
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#17327726661991332-450: A key advantage of digital signals over analogue signals. However, digital systems fail catastrophically when noise exceeds the system's ability to autocorrect. On the other hand, analogue systems fail gracefully: as noise increases, the signal becomes progressively more degraded but still usable. Also, digital transmission of continuous data unavoidably adds quantization noise to the output. This can be reduced, but not eliminated, only at
1443-837: A new international frequency list and used in conformity with the Radio Regulation". According to the ITU's Radio Regulations adopted in Atlantic City, all frequencies referenced in the International Frequency Registration Board , examined by the board and registered on the International Frequency List "shall have the right to international protection from harmful interference". From a global perspective, there have been political debates and legislation regarding
1554-436: A person's age, interests, sexual preference and relationship status. In this way, these sites can play important role in everything from organising social engagements to courtship . Prior to social networking sites, technologies like short message service (SMS) and the telephone also had a significant impact on social interactions. In 2000, market research group Ipsos MORI reported that 81% of 15- to 24-year-old SMS users in
1665-751: A postal system in the Empire, appointing Franz von Taxis to run it. This system, originally the Kaiserliche Reichspost , is often considered the first modern postal service in the world, which initiated a revolution in communication in Europe. The system combined contemporary technical and organization means to create a stable transcontinental service which was also the first to offer (fee-based) public access. The Thurn und Taxis family, then known as Tassis, had operated postal services between Italian city-states from 1290 onward. For 500 years
1776-636: A private mail service. Notably, the Cistercians had one which connected more than 6,000 abbeys , monasteries , and churches. The best organization, however, was created by the Knights Templar . In 1716, Correos y Telégrafos was established in Spain as public mail service, available to all citizens. Delivery postmen were first employed in 1756 and post boxes were installed firstly in 1762. In 1505, Holy Roman Emperor Maximilian I established
1887-490: A radio as the channel "96 FM"). In addition, modulation has the advantage that it may use frequency division multiplexing (FDM). A telecommunications network is a collection of transmitters, receivers, and communications channels that send messages to one another. Some digital communications networks contain one or more routers that work together to transmit information to the correct user. An analogue communications network consists of one or more switches that establish
1998-474: A service that operated for a year until the gap in the telegraph link was closed. In the Middle Ages, chains of beacons were commonly used on hilltops as a means of relaying a signal. Beacon chains suffered the drawback that they could only pass a single bit of information, so the meaning of the message such as "the enemy has been sighted" had to be agreed upon in advance. One notable instance of their use
2109-442: A single medium to transmit several concurrent communication sessions . Several methods of long-distance communication before the modern era used sounds like coded drumbeats , the blowing of horns , and whistles . Long-distance technologies invented during the 20th and 21st centuries generally use electric power, and include the telegraph , telephone , television , and radio . Early telecommunication networks used metal wires as
2220-587: A small Telephone Boutique next to a historic Postal mansion his ancestors used to go to centuries earlier. Several European Post Carriers like Deutsche Post or Österreichische Post continue to use the Thurn & Taxis Post Horn in their company logo just like the global Phone Book of the World based in the old Postal mansion of King Louis XIV in Paris. In the United Kingdom, prior to 1840 letters were paid for by
2331-497: A suspected criminal conspiracy, although black chambers (largely in the past, though there is apparently some continuance of their use today) opened extralegally. The mail service may be allowed to open the mail if neither addressee nor sender can be located, in order to attempt to locate either. Mail service may also open the mail to inspect if it contains materials that are hazardous to transport or violate local laws. ITU Radio Regulations The ITU Radio Regulations ( RR )
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#17327726661992442-411: A telephone network, the caller is connected to the person to whom they wish to talk by switches at various telephone exchanges . The switches form an electrical connection between the two users and the setting of these switches is determined electronically when the caller dials the number. Once the connection is made, the caller's voice is transformed to an electrical signal using a small microphone in
2553-411: A version of the electrical telegraph that he unsuccessfully demonstrated on September 2, 1837. His code was an important advance over Wheatstone's signaling method. The first transatlantic telegraph cable was successfully completed on July 27, 1866, allowing transatlantic telecommunication for the first time. The conventional telephone was patented by Alexander Bell in 1876. Elisha Gray also filed
2664-786: Is a basic document of the International Telecommunication Union (ITU) that regulates on law of nations scale radiocommunication services and the utilisation of radio frequencies . It is the supplementation to the ITU Constitution and Convention and in line with the ITU International Telecommunication Regulations (ITR). The ITU RR comprise and regulate the part of the allocated electromagnetic spectrum (also: radio frequency spectrum ) from 9 kHz to 300 GHz. The current approved version of
2775-577: Is adapted from the French, because its written use was recorded in 1904 by the French engineer and novelist Édouard Estaunié . Communication was first used as an English word in the late 14th century. It comes from Old French comunicacion (14c., Modern French communication), from Latin communicationem (nominative communication), noun of action from past participle stem of communicare, "to share, divide out; communicate, impart, inform; join, unite, participate in," literally, "to make common", from communis". At
2886-670: Is called point-to-point communication because it occurs between a transmitter and a receiver. Telecommunication through radio broadcasts is called broadcast communication because it occurs between a powerful transmitter and numerous low-power but sensitive radio receivers. Telecommunications in which multiple transmitters and multiple receivers have been designed to cooperate and share the same physical channel are called multiplex systems . The sharing of physical channels using multiplexing often results in significant cost reduction. Multiplexed systems are laid out in telecommunication networks and multiplexed signals are switched at nodes through to
2997-451: Is called (in the jargon of the field) " quadrature amplitude modulation " (QAM) that are used in high-capacity digital radio communication systems. Modulation can also be used to transmit the information of low-frequency analogue signals at higher frequencies. This is helpful because low-frequency analogue signals cannot be effectively transmitted over free space. Hence the information from a low-frequency analogue signal must be impressed into
3108-432: Is commonly called "keying" —a term derived from the older use of Morse Code in telecommunications—and several keying techniques exist (these include phase-shift keying , frequency-shift keying , and amplitude-shift keying ). The " Bluetooth " system, for example, uses phase-shift keying to exchange information between various devices. In addition, there are combinations of phase-shift keying and amplitude-shift keying which
3219-793: Is converted from electricity to sound. Telecommunication systems are occasionally "duplex" (two-way systems) with a single box of electronics working as both the transmitter and a receiver, or a transceiver (e.g., a mobile phone ). The transmission electronics and the receiver electronics within a transceiver are quite independent of one another. This can be explained by the fact that radio transmitters contain power amplifiers that operate with electrical powers measured in watts or kilowatts, but radio receivers deal with radio powers measured in microwatts or nanowatts . Hence, transceivers have to be carefully designed and built to isolate their high-power circuitry and their low-power circuitry from each other to avoid interference. Telecommunication over fixed lines
3330-481: Is degraded by undesirable noise . Commonly, the noise in a communication system can be expressed as adding or subtracting from the desirable signal via a random process . This form of noise is called additive noise , with the understanding that the noise can be negative or positive at different instances. Unless the additive noise disturbance exceeds a certain threshold, the information contained in digital signals will remain intact. Their resistance to noise represents
3441-606: Is derived from Old French poste , which ultimately stems from the past participle of the Latin verb ponere 'to lay down or place'. So in the U.K., the Royal Mail delivers the post , while in North America both the U.S. Postal Service and Canada Post deliver the mail . The term email , short for "electronic mail", first appeared in the 1970s. The term snail mail is a retronym to distinguish it from
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3552-926: Is in Egypt , where Pharaohs used couriers to send out decrees throughout the territory of the state (2400 BCE). The earliest surviving piece of mail is also Egyptian, dating to 255 BCE. The first credible claim for the development of a real postal system comes from Ancient Persia . The best-documented claim ( Xenophon ) attributes the invention to the Persian King Cyrus the Great (550 BCE), who mandated that every province in his kingdom would organize reception and delivery of post to each of its citizens. Other writers credit his successor Darius I of Persia (521 BCE). Other sources claim much earlier dates for an Assyrian postal system, with credit given to Hammurabi (1700 BCE) and Sargon II (722 BCE). Mail may not have been
3663-608: Is self-evident in the case of online retailer Amazon.com but, according to academic Edward Lenert, even the conventional retailer Walmart has benefited from better telecommunication infrastructure compared to its competitors. In cities throughout the world, home owners use their telephones to order and arrange a variety of home services ranging from pizza deliveries to electricians. Even relatively poor communities have been noted to use telecommunication to their advantage. In Bangladesh 's Narsingdi District , isolated villagers use cellular phones to speak directly to wholesalers and arrange
3774-448: Is separated from its adjacent stations by 200 kHz, and the difference between 200 kHz and 180 kHz (20 kHz) is an engineering allowance for the imperfections in the communication system. In the example above, the "free space channel" has been divided into communications channels according to frequencies , and each channel is assigned a separate frequency bandwidth in which to broadcast radio waves. This system of dividing
3885-446: Is the informational equivalent of two newspaper pages per person per day in 1986, and six entire newspapers per person per day by 2007. Given this growth, telecommunications play an increasingly important role in the world economy and the global telecommunications industry was about a $ 4.7 trillion sector in 2012. The service revenue of the global telecommunications industry was estimated to be $ 1.5 trillion in 2010, corresponding to 2.4% of
3996-576: The Han dynasty (206 BCE – 220 CE), who had relay stations every 30 li (about 15km) along major routes. The Tang dynasty (618 to 907 AD) operated a recorded 1,639 posthouses, including maritime offices, employing around 20,000 people. The system was administered by the Ministry of War and private correspondence was forbidden from the network. The Ming dynasty (1368 to 1644) sought a postal system to deliver mail quickly, securely, and cheaply. Adequate speed
4107-771: The Nipkow disk by Paul Nipkow and thus became known as the mechanical television . It formed the basis of experimental broadcasts done by the British Broadcasting Corporation beginning on 30 September 1929. However, for most of the 20th century, televisions depended on the cathode ray tube invented by Karl Ferdinand Braun . The first version of such a television to show promise was produced by Philo Farnsworth and demonstrated to his family on 7 September 1927. After World War II, interrupted experiments resumed and television became an important home entertainment broadcast medium. The type of device known as
4218-584: The Radio Regulations is the responsibility of the World Radiocommunication Conferences (WRCs) of the ITU, meetings of which are typically held every three or four years. Recent WRCs are: The most recent published version of the Radio Regulations , the "Edition of 2016" contains the complete texts of the Radio Regulations as adopted and revised by WRC-15, including all articles, appendices, resolutions, and
4329-475: The U.S. Postal Service authorised the first tests of a secure system of sending digital franks via the Internet to be printed out on a PC printer, obviating the necessity to license a dedicated franking machine and allowing companies with smaller mail programs to make use of the option; this was later expanded to test the use of personalized postage. The service provided by the U.S. Postal Service in 2003 allows
4440-648: The Wodeyar dynasty (1399–1947) of the Kingdom of Mysore used mail service for espionage purposes thereby acquiring knowledge related to matters that took place at great distances. By the end of the 18th century, a postal system in India was in operation. Later this system underwent complete modernization when the British Raj established its control over most of India. The Post Office Act XVII of 1837 provided that
4551-439: The spark gap transmitter for radio or mechanical computers for computing, it was the invention of the thermionic vacuum tube that made these technologies widespread and practical, leading to the creation of electronics . In the 1940s, the invention of semiconductor devices made it possible to produce solid-state devices, which are smaller, cheaper, and more efficient, reliable, and durable than thermionic tubes. Starting in
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4662-491: The 17th century, the word mail began to appear as a reference for a bag that contained letters: "bag full of letter" (1654). Over the next hundred years the word mail began to be applied strictly to the letters themselves and the sack as the mailbag . In the 19th century, the British typically used mail to refer to letters being sent abroad (i.e. on a ship) and post to refer to letters for domestic delivery. The word Post
4773-610: The 1932 Plenipotentiary Telegraph Conference and the International Radiotelegraph Conference in Madrid, the two organizations merged to form the International Telecommunication Union (ITU). They defined telecommunication as "any telegraphic or telephonic communication of signs, signals, writing, facsimiles and sounds of any kind, by wire, wireless or other systems or processes of electric signaling or visual signaling (semaphores)." The definition
4884-496: The 1970s. In the 1960s, Paul Baran and, independently, Donald Davies started to investigate packet switching , a technology that sends a message in portions to its destination asynchronously without passing it through a centralized mainframe . A four-node network emerged on 5 December 1969, constituting the beginnings of the ARPANET , which by 1981 had grown to 213 nodes . ARPANET eventually merged with other networks to form
4995-628: The August Revolution, the Post and Wireless Office was renamed the Post Office under the Ministry of Transportation. In 1955, the Post Office was upgraded to the Ministry of Post. Some Chinese sources claim mail or postal systems dating back to the Xia or Shang dynasties , which would be the oldest mailing service in the world. The earliest credible system of couriers was initiated by
5106-684: The Governor-General of India in Council had the exclusive right of conveying letters by post for hire within the territories of the East India Company. The mails were available to certain officials without charge, which became a controversial privilege as the years passed. On this basis the Indian Post Office was established on October 1, 1837. The first well-documented postal service was that of Rome . Organized at
5217-506: The ITU Radio Regulations (addition 2012) is structured as follows: Volume 1 – Articles Volume 2 – Appendices Volume 3 – Resolutions and Recommendations Volume 4 – ITU-R Recommendations incorporated by reference Maps to be used in relation to Appendix 27 The Radio Regulations define: Radio communication services (or sradiocommunication services ) are sub-divided into space-based radiocommunication , involving
5328-464: The ITU was able to compile an index that measures the overall ability of citizens to access and use information and communication technologies. Using this measure, Sweden, Denmark and Iceland received the highest ranking while the African countries Niger , Burkina Faso and Mali received the lowest. Telecommunication has played a significant role in social relationships. Nevertheless, devices like
5439-742: The Internet. While Internet development was a focus of the Internet Engineering Task Force (IETF) who published a series of Request for Comments documents, other networking advancements occurred in industrial laboratories , such as the local area network (LAN) developments of Ethernet (1983), Token Ring (1984)and Star network topology. The effective capacity to exchange information worldwide through two-way telecommunication networks grew from 281 petabytes (PB) of optimally compressed information in 1986 to 471 PB in 1993 to 2.2 exabytes (EB) in 2000 to 65 EB in 2007. This
5550-441: The United Kingdom had used the service to coordinate social arrangements and 42% to flirt. In cultural terms, telecommunication has increased the public's ability to access music and film. With television, people can watch films they have not seen before in their own home without having to travel to the video store or cinema. With radio and the Internet, people can listen to music they have not heard before without having to travel to
5661-489: The United States Postal Service's experiment with rocket mail . Receipt services were made available in order to grant the sender a confirmation of effective delivery. Before about the mid-nineteenth century, in regions where postal systems existed, the payment models varied, but most mail was sent unpaid requiring the recipient to pay the postage fee. In some regions a partial payment was made by
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#17327726661995772-732: The United States was spent on media that depend upon telecommunication. Many countries have enacted legislation which conforms to the International Telecommunication Regulations established by the International Telecommunication Union (ITU), which is the "leading UN agency for information and communication technology issues". In 1947, at the Atlantic City Conference, the ITU decided to "afford international protection to all frequencies registered in
5883-490: The United States, postcodes in the United Kingdom and Australia, eircodes in Ireland and postal codes in most other countries) in order to facilitate the automation of operations. This also includes placing additional marks on the address portion of the letter or mailed object, called "bar coding". Bar coding of mail for delivery is usually expressed either by a series of vertical bars, usually called POSTNET coding or
5994-459: The agent usually indicates by means of a cancellation that it is no longer valid for pre-payment of postage. The exceptions are when the agent forgets or neglects to cancel the mailpiece, for stamps that are pre-cancelled and thus do not require cancellation and for, in most cases, metered mail. (The "personalized stamps" authorized by the USPS and manufactured by Zazzle and other companies are in fact
6105-636: The caller's handset . This electrical signal is then sent through the network to the user at the other end where it is transformed back into sound by a small speaker in that person's handset. Postal mail Postal authorities often have functions aside from transporting letters. In some countries, a postal, telegraph and telephone (PTT) service oversees the postal system, in addition to telephone and telegraph systems. Some countries' postal systems allow for savings accounts and handle applications for passports . The Universal Postal Union (UPU), established in 1874, includes 192 member countries and sets
6216-512: The conditions for physical mail. Email (and in recent years social networking sites) became a fierce competitor to physical mail systems, but online auctions and Internet shopping opened new business opportunities as people often get items bought online through the mail. Modern mail is organized by national and privatized services, which are reciprocally connected by international regulations, organizations and international agreements. Paper letters and parcels can be sent to almost any country in
6327-436: The correct destination terminal receiver. Communications can be encoded as analogue or digital signals , which may in turn be carried by analogue or digital communication systems. Analogue signals vary continuously with respect to the information, while digital signals encode information as a set of discrete values (e.g., a set of ones and zeroes). During propagation and reception, information contained in analogue signals
6438-515: The development of optical fibre. The Internet , a technology independent of any given medium, has provided global access to services for individual users and further reduced location and time limitations on communications. Telecommunication is a compound noun of the Greek prefix tele- (τῆλε), meaning distant , far off , or afar , and the Latin verb communicare , meaning to share . Its modern use
6549-536: The device—from the cathode to the anode. Adding one or more control grids within the tube enables the current between the cathode and anode to be controlled by the voltage on the grid or grids. These devices became a key component of electronic circuits for the first half of the 20th century and were crucial to the development of radio, television, radar, sound recording and reproduction , long-distance telephone networks, and analogue and early digital computers . While some applications had used earlier technologies such as
6660-418: The electrical telegraph, the last commercial line was abandoned in 1880. On July 25, 1837, the first commercial electrical telegraph was demonstrated by English inventor Sir William Fothergill Cooke and English scientist Sir Charles Wheatstone . Both inventors viewed their device as "an improvement to the [existing] electromagnetic telegraph" and not as a new device. Samuel Morse independently developed
6771-501: The enormous funding necessary to rapidly industrialize Japan in the late 19th century. The postal service was one of Korea's first attempts at modernization. The Joseon Post Office was established in 1884. Another important postal service was created in the Islamic world by the caliph Mu'awiyya; the service was called barid , for the name of the towers built to protect the roads by which couriers travelled. By 3000 BC, Egypt
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#17327726661996882-403: The expense of increasing the channel bandwidth requirement. The term "channel" has two different meanings. In one meaning, a channel is the physical medium that carries a signal between the transmitter and the receiver. Examples of this include the atmosphere for sound communications, glass optical fibres for some kinds of optical communications , coaxial cables for communications by way of
6993-405: The franks to be printed out on special adhesive-backed labels. In 2004 the Royal Mail in the United Kingdom introduced its SmartStamp Internet-based system, allowing printing on ordinary adhesive labels or envelopes. Similar systems are being considered by postal administrations around the world. When the pre-paid envelope or package is accepted into the mail by an agent of the postal service,
7104-429: The importance of social conversations and staying connected to family and friends. Since then the role that telecommunications has played in social relations has become increasingly important. In recent years, the popularity of social networking sites has increased dramatically. These sites allow users to communicate with each other as well as post photographs, events and profiles for others to see. The profiles can list
7215-400: The last postmaster, Maximilian Karl, 6th Prince of Thurn and Taxis , into real estate, most of it continuing to exist today. The Phone Book of the World has its roots in the long history of the avant-garde telecommunications family Thurn & Taxis. The directory is the result of Johannes, 11th Prince of Thurn & Taxis transmitting PTT culture to a student and helping with the opening of
7326-428: The mail and packages often surveyed and their contents sometimes edited out (or even in). There have been cases over the millennia of governments opening and copying or photographing the contents of private mail. Subject to the laws in the relevant jurisdiction, correspondence may be openly or covertly opened, or the contents determined via some other method, by the police or other authorities in some cases relating to
7437-477: The mail service. Foreign observers, such as Marco Polo , have attested to the efficiency of this early postal system. Each station was maintained by up to twenty five families. Work for postal service counted as military service. The system was still operational in 18th century when 64 stations were required for a message to cross Mongolia from the Altai Mountains to China. The modern Japanese system
7548-548: The management of telecommunication and broadcasting. The history of broadcasting discusses some debates in relation to balancing conventional communication such as printing and telecommunication such as radio broadcasting. The onset of World War II brought on the first explosion of international broadcasting propaganda. Countries, their governments, insurgents, terrorists, and militiamen have all used telecommunication and broadcasting techniques to promote propaganda. Patriotic propaganda for political movements and colonization started
7659-479: The medium for transmitting signals. These networks were used for telegraphy and telephony for many decades. In the first decade of the 20th century, a revolution in wireless communication began with breakthroughs including those made in radio communications by Guglielmo Marconi , who won the 1909 Nobel Prize in Physics . Other early pioneers in electrical and electronic telecommunications include co-inventors of
7770-567: The medium into channels according to frequency is called " frequency-division multiplexing ". Another term for the same concept is " wavelength-division multiplexing ", which is more commonly used in optical communications when multiple transmitters share the same physical medium. Another way of dividing a communications medium into channels is to allocate each sender a recurring segment of time (a "time slot", for example, 20 milliseconds out of each second), and to allow each sender to send messages only within its own time slot. This method of dividing
7881-414: The medium into communication channels is called " time-division multiplexing " ( TDM ), and is used in optical fibre communication. Some radio communication systems use TDM within an allocated FDM channel. Hence, these systems use a hybrid of TDM and FDM. The shaping of a signal to convey information is known as modulation . Modulation can be used to represent a digital message as an analogue waveform. This
7992-603: The message carrier (called Chapar ) would ride to the next post, whereupon he would swap his horse with a fresh one for maximum performance and delivery speed. Herodotus described the system in this way: "It is said that as many days as there are in the whole journey, so many are the men and horses that stand along the road, each horse and man at the interval of a day's journey; and these are stayed neither by snow nor rain nor heat nor darkness from accomplishing their appointed course with all speed". The verse prominently features on New York's James Farley Post Office , although it uses
8103-733: The mid-1930s. In 1936, the BBC broadcast propaganda to the Arab World to partly counter similar broadcasts from Italy, which also had colonial interests in North Africa. Modern political debates in telecommunication include the reclassification of broadband Internet service as a telecommunications service (also called net neutrality ), regulation of phone spam , and expanding affordable broadband access. According to data collected by Gartner and Ars Technica sales of main consumer's telecommunication equipment worldwide in millions of units was: In
8214-595: The mid-1960s, thermionic tubes were replaced with the transistor . Thermionic tubes still have some applications for certain high-frequency amplifiers. On 11 September 1940, George Stibitz transmitted problems for his Complex Number Calculator in New York using a teletype and received the computed results back at Dartmouth College in New Hampshire . This configuration of a centralized computer ( mainframe ) with remote dumb terminals remained popular well into
8325-452: The music store. Telecommunication has also transformed the way people receive their news. A 2006 survey (right table) of slightly more than 3,000 Americans by the non-profit Pew Internet and American Life Project in the United States the majority specified television or radio over newspapers. Telecommunication has had an equally significant impact on advertising. TNS Media Intelligence reported that in 2007, 58% of advertising expenditure in
8436-500: The nature of the service being provided rather than the international concept of a radiocommunication service. In other words, the term "service" can be used in these two different ways. No matter what definitions are adopted in a given country, with some specific exceptions which are allowed for in the ITU RRs, the use of the spectrum must fit in with the international definitions of radio services. The drafting, revision and adoption of
8547-400: The neighbourhood of 94.5 MHz (megahertz) while another radio station can simultaneously broadcast radio waves at frequencies in the neighbourhood of 96.1 MHz. Each radio station would transmit radio waves over a frequency bandwidth of about 180 kHz (kilohertz), centred at frequencies such as the above, which are called the "carrier frequencies" . Each station in this example
8658-715: The postal business based in Brussels and in Frankfurt was passed from one generation to another. Following the abolition of the Empire in 1806, the Thurn-und-Taxis Post system continued as a private organization into the postage stamp era before being absorbed into the postal system of the new German Empire after 1871. 1867 July 1 the State of Prussia had to make a compensation payment of 3.000.000 Thalers reinvested by Helene von Thurn & Taxis , daughter-in-law of
8769-515: The presence or absence of an atmosphere between the two. Radio waves travel through a perfect vacuum just as easily as they travel through air, fog, clouds, or any other kind of gas. The other meaning of the term "channel" in telecommunications is seen in the phrase communications channel , which is a subdivision of a transmission medium so that it can be used to send multiple streams of information simultaneously. For example, one radio station can broadcast radio waves into free space at frequencies in
8880-454: The primary mission of this postal service, however. The role of the system as an intelligence gathering apparatus is well documented, and the service was (later) called angariae , a term that in time came to indicate a tax system. The Old Testament ( Esther , VIII) makes mention of this system: Ahasuerus , king of Medes , used couriers for communicating his decisions. The Persian system worked using stations (called Chapar-Khaneh ), whence
8991-411: The public. Common chariots called Dagana were sometimes used as mail chariots in ancient India. Couriers were used militarily by kings and local rulers to deliver information through runners and other carriers. The postmaster, the head of the intelligence service, was responsible for ensuring the maintenance of the courier system. Couriers were also used to deliver personal letters. In South India ,
9102-428: The quicker email. Various dates have been given for its first use. The practice of communication by written documents carried by an intermediary from one person or place to another almost certainly dates back nearly to the invention of writing . However, the development of formal postal systems occurred much later. The first documented use of an organized courier service for the dissemination of written documents
9213-417: The recipient and the cost was determined by the distance from sender to recipient and the number of sheets of paper rather than by a countrywide flat rate with weight restrictions. Sir Rowland Hill reformed the postal system based on the concepts of penny postage and prepayment. In his proposal, Hill also called for official pre-printed envelopes and adhesive postage stamps as alternative ways of getting
9324-641: The recording of identities of sender and recipient. The privacy of correspondence is guaranteed by the constitutions of Mexico , Colombia , Brazil and Venezuela , and is alluded to in the European Convention on Human Rights and the Universal Declaration of Human Rights . The control of the contents inside private citizens' mail is censorship and concerns social, political, and legal aspects of civil rights . International mail and packages are subject to customs control, with
9435-708: The relationship as causal. Because of the economic benefits of good telecommunication infrastructure, there is increasing worry about the inequitable access to telecommunication services amongst various countries of the world—this is known as the digital divide . A 2003 survey by the International Telecommunication Union (ITU) revealed that roughly a third of countries have fewer than one mobile subscription for every 20 people and one-third of countries have fewer than one land-line telephone subscription for every 20 people. In terms of Internet access, roughly half of all countries have fewer than one out of 20 people with Internet access. From this information, as well as educational data,
9546-584: The rules for international mail exchanges as a Specialized Agency of the United Nations . The word mail comes from the Middle English word male , referring to a travelling bag or pack. It was spelled in that manner until the 17th century and is distinct from the word male . The French have a similar word, malle , for a trunk or large box, and mála is the Irish term for a bag. In
9657-538: The sender to pay for the postage, at a time when prepayment was optional, which led to the invention of the postage stamp, the Penny Black . The postal system was important in the development of modern transportation. Railways carried railway post offices . During the 20th century, air mail became the transport of choice for inter-continental mail. Postmen started to use mail trucks . The handling of mail became increasingly automated. The Internet came to change
9768-435: The sender. Today, worldwide, the most common method of prepaying postage is by buying an adhesive postage stamp to be applied to the envelope before mailing; a much less common method is to use a postage-prepaid envelope . Franking is a method of creating postage-prepaid envelopes under licence using a special machine. They are used by companies with large mail programs, such as banks and direct mail companies. In 1998,
9879-427: The standard frequency and time signal service, various satellite services. Further sub-sets of some of these internationally defined services are often created at the national level. For example, within the land mobile service, a country may choose to define such services as paging, dispatch two-way radio service, cellular mobile telephone service, trunked mobile radio service, etc. Many of these definitions are based upon
9990-609: The telegraph Charles Wheatstone and Samuel Morse , numerous inventors and developers of the telephone including Antonio Meucci , Philipp Reis , Elisha Gray and Alexander Graham Bell , inventors of radio Edwin Armstrong and Lee de Forest , as well as inventors of television like Vladimir K. Zworykin , John Logie Baird and Philo Farnsworth . Since the 1960s, the proliferation of digital technologies has meant that voice communications have gradually been supplemented by data. The physical limitations of metallic media prompted
10101-412: The telephone system were originally advertised with an emphasis on the practical dimensions of the device (such as the ability to conduct business or order home services) as opposed to the social dimensions. It was not until the late 1920s and 1930s that the social dimensions of the device became a prominent theme in telephone advertisements. New promotions started appealing to consumers' emotions, stressing
10212-630: The then-newly discovered phenomenon of radio waves , demonstrating, by 1901, that they could be transmitted across the Atlantic Ocean. This was the start of wireless telegraphy by radio. On 17 December 1902, a transmission from the Marconi station in Glace Bay, Nova Scotia, Canada , became the world's first radio message to cross the Atlantic from North America. In 1904, a commercial service
10323-433: The time of Augustus Caesar (62 BCE – 14 CE), the service was called cursus publicus and was provided with light carriages ( rhedæ ) pulled by fast horses. By the time of Diocletian , a parallel service was established with two-wheeled carts ( birotæ ) pulled by oxen . This service was reserved for government correspondence. Yet another service for citizens was later added. In 1802, the first Vietnamese postal service
10434-480: The translation "Neither snow nor rain nor heat nor gloom of night stays these couriers from the swift completion of their appointed rounds". The economic growth and political stability under the Mauryan Empire (322–185 BCE) stimulated sustained development of civil infrastructure in ancient India . The Mauryans developed early Indian mail service as well as public wells, rest houses, and other facilities for
10545-487: The transport of foreign and domestic tribute specifically and the conduct of trade in general. By the end of Kublai Khan's rule, there were more than 1400 postal stations in China alone, which in turn had at their disposal about 50,000 horses, 1,400 oxen, 6,700 mules, 400 carts, 6,000 boats, more than 200 dogs, and 1,150 sheep. The stations were 25 to 65 km (16 to 40 mi) apart and had reliable attendants working for
10656-409: The use of one or more space stations or the use of one or more reflecting satellites or other objects in space; and terrestrial radiocommunication , which excludes space radiocommunication and radio astronomy . The ITU Radio Regulations sets out the definitions of some 40 radio services including such services as the fixed service, the mobile service, the land mobile service, the broadcasting service,
10767-489: The voltages and electric currents in them, and free space for communications using visible light , infrared waves, ultraviolet light , and radio waves . Coaxial cable types are classified by RG type or "radio guide", terminology derived from World War II. The various RG designations are used to classify the specific signal transmission applications. This last channel is called the "free space channel". The sending of radio waves from one place to another has nothing to do with
10878-436: The wartime purposes of aircraft and land communication, radio navigation, and radar. Development of stereo FM broadcasting of radio began in the 1930s in the United States and the 1940s in the United Kingdom, displacing AM as the dominant commercial standard in the 1970s. On March 25, 1925, John Logie Baird demonstrated the transmission of moving pictures at the London department store Selfridges . Baird's device relied upon
10989-561: The whole territory of his empire the system used by Franks in northern Gaul and connected this service with that of missi dominici . In the mid-11th century, flax traders known as the Cairo Geniza Merchants from Fustat , Egypt wrote about using a postal service known as the kutubi. The kutubi system managed routes between the cities of Jerusalem, Ramla, Tyre, Ascalon, Damascus, Aleppo, and Fustat with year-round, regular mail delivery. Many religious orders had
11100-489: The world relatively easily and cheaply. The Internet has made the process of sending letter-like messages nearly instantaneous, and in many cases and situations correspondents use email where they previously would have used letters. The volume of paper mail sent through the U.S. Postal Service has declined by more than 15% since its peak at 213 billion pieces per annum in 2006. Some countries have organized their mail services as public limited liability corporations without
11211-417: The world's gross domestic product (GDP). Modern telecommunication is founded on a series of key concepts that experienced progressive development and refinement in a period of well over a century: Telecommunication technologies may primarily be divided into wired and wireless methods. Overall, a basic telecommunication system consists of three main parts that are always present in some form or another: In
11322-454: Was always a problem, because of the slow overland transportation system, and underfunding. Its network had 1,936 posthouses every 60 li along major routes, with fresh horses available every 10 li between them. The Qing operated 1,785 posthouses throughout their lands. More efficient, however, was the system linking the international settlements, centered around Shanghai and the Treaty ports. It
11433-478: Was developed in the mid-19th century, closely copying European models. Japan was highly innovative in developing the world's largest and most successful postal savings system and later a postal life insurance system as well. Postmasters play a key role in linking the Japanese political system to local politics. The postmasters are high prestige, and are often hereditary. To a large extent, the postal system generated
11544-488: Was during the Spanish Armada , when a beacon chain relayed a signal from Plymouth to London . In 1792, Claude Chappe , a French engineer, built the first fixed visual telegraphy system (or semaphore line ) between Lille and Paris. However semaphore suffered from the need for skilled operators and expensive towers at intervals of ten to thirty kilometres (six to nineteen miles). As a result of competition from
11655-406: Was established to transmit nightly news summaries to subscribing ships, which incorporated them into their onboard newspapers. World War I accelerated the development of radio for military communications . After the war, commercial radio AM broadcasting began in the 1920s and became an important mass medium for entertainment and news. World War II again accelerated the development of radio for
11766-505: Was established under the Nguyen dynasty , under the Ministry of Rites. During the Nguyen dynasty, official documents were transported by horse and other primitive means to stations built about 25-30 kilometers apart. In 1904, three wireless communication offices were established, and in early 1906 they were merged with the postal service to form the Post and Wireless Office. In 1945, after
11877-471: Was later reconfirmed, according to Article 1.3 of the ITU Radio Regulations , which defined it as "Any transmission , emission or reception of signs, signals, writings, images and sounds or intelligence of any nature by wire , radio, optical, or other electromagnetic systems". Homing pigeons have been used throughout history by different cultures. Pigeon post had Persian roots and
11988-674: Was later used by the Romans to aid their military. Frontinus claimed Julius Caesar used pigeons as messengers in his conquest of Gaul . The Greeks also conveyed the names of the victors at the Olympic Games to various cities using homing pigeons. In the early 19th century, the Dutch government used the system in Java and Sumatra . And in 1849, Paul Julius Reuter started a pigeon service to fly stock prices between Aachen and Brussels ,
12099-483: Was of little practical value because it relied on the electrophonic effect requiring users to place the receiver in their mouths to "hear". The first commercial telephone services were set up by the Bell Telephone Company in 1878 and 1879 on both sides of the Atlantic in the cities of New Haven and London. In 1894, Italian inventor Guglielmo Marconi began developing a wireless communication using
12210-611: Was the main communication system for China's international trade. Genghis Khan installed an empire-wide messenger and postal station system named Örtöö within the Mongol Empire . During the Yuan dynasty under Kublai Khan , this system also covered the territory of China. Postal stations were used not only for the transmission and delivery of official mail but were also available for travelling officials, military men, and foreign dignitaries. These stations aided and facilitated
12321-438: Was using homing pigeons for pigeon post , taking advantage of a singular quality of this bird, which when taken far from its nest is able to find its way home due to a particularly developed sense of orientation. Messages were then tied around the legs of the pigeon, which was freed and could reach its original nest. By the 19th century, homing pigeons were used extensively for military communications. Charlemagne extended to
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