History of Telecommunications


Коммуникация, связь, радиоэлектроника и цифровые приборы

The first practical telecommunications device to make use of this discovery was the telegraph. The Telegraph Beginning in the mid-1800s the telegraph delivered the first inter-city transcontinental and transoceanic messages in the world.



33 KB

0 чел.

History of Telecommunications

Communicating over long distances has been a challenge throughout history. In ancient times, runners were used to carry important between messages rulers or other important people. Other forms of long-distance communication included smoke signals, chains of searchlights and flags to send a message from one tower to another, carrier pigeons, and horses. Modern telecommunications began with the discovery that electricity can be used to transmit a signal. For the first time, a signal could be sent faster than any other mode of transportation. The first practical telecommunications device to make use of this discovery was the telegraph.

1. The Telegraph

Beginning in the mid-1800s, the telegraph delivered the first inter-city, transcontinental, and transoceanic messages in the world. The telegraph revolutionized the way people communicated by providing messages faster than any other means provided at the time. American art professor Samuel F.B. Morse pursued an interest in electromagnetism to create a practical electromagnetic telegraph in 1837. Morse partnered with Alfred Vail and was able to commercialize the technology with financial support from the U.S. government. In 1843 Morse built a demonstration telegraph link between Washington, D.C., and Baltimore, Maryland. On May 24, 1844, the network was inaugurated for commercial use with the message, "What hath God wrought!"

Telegraph use quickly spread; the first transcontinental link was completed in 1861 between San Francisco, California, and Washington, D.C. Railroad companies and newspapers were the first major telegraphy users. Telegraph lines were constructed parallel to railroad beds. Telegraphy helped the railroads manage traffic and allowed news organizations to distribute stories quickly to local newspapers. Within a few years, several telegraph companies were in operation, each with its own network of telegraph wires. Consolidation occurred in the telegraph industry (as it has in numerous telecommunications industries), and by the 1870s the Western Union Telegraph Company emerged as the dominant operator.

2. Commercial Growth of the Telephone

In 1876 American inventor Alexander Graham Bell ushered in a new era of voice and sound telecommunication when he uttered to his assistant the words, "Mr. Watson, come here; I want you," using a prototype telephone. Bell received the patent for the first telephone, but he had to fight numerous legal challenges to his patent from other inventors with similar devices. Bell was able to make his prototype telephone work and attract financial backers, and his company grew. The telephone was a vast improvement over the telegraph system, which could only transmit coded words and numbers, not the sound of a human voice. Telegraph messages had to be deciphered by trained operators, written down, and then delivered by hand to the receiving party, all of which took time. The telephone transmitted actual sound messages and made telecommunication immediate. Improved switching technology (the technology used to transfer calls from one local network to another) meant individual telephones could be connected for personal conversations.

The first commercial telephone line was installed in Boston, Massachusetts, in 1877. Early telephones required direct connections to other telephones, but this problem was solved with telephone exchange switches, the first of which was installed in New Haven, Connecticut, in 1878. A telephone exchange linked telephones in a given area together, so a connection between the telephone and the exchange was all that was needed. Telephones were much more convenient and personal than telegrams, and their use quickly spread. By 1913 telephone lines from New York City to San Francisco had been established, and by 1930 radio signals could transmit telephone calls between New York and London, England. Eventually, long-distance telephone service in the United States was consolidated into one company, the American Telephone and Telegraph Company (now known as AT&T Corp.), which was a regulated monopoly.

3. The Emergence of Broadcasting

Telephones and telegraphs are point-to-point systems of telecommunications, but with the invention of the radio, point-to-multipoint signals could be sent through a central transmitter to be received by anyone possessing a receiver. Italian inventor and electrical engineer Guglielmo Marconi transmitted a Morse-code telegraph signal by radio in 1895. This began a revolution in wireless telegraphy that would later result in broadcast radios that could transmit actual voice and music. Radio and wireless telegraph communication played an important role during World War I (1914-1918), allowing military personnel to communicate instantly with troops in remote locations. United States president Woodrow Wilson was impressed with the ability of radio, but he was fearful of its potential for espionage use. He banned nonmilitary radio use in the United States as the nation entered World War I in 1917, and this stifled commercial development of the medium. After the war, however, commercial radio stations began to broadcast. By the mid-1920s, millions of radio listeners tuned in to music, news, and entertainment programming.

Television got its start as a mass-communication medium shortly after World War II (1939-1945). The expense of television transmission prevented its use as a two-way medium, but radio broadcasters quickly saw the potential for television to provide a new way of bringing news and entertainment programming to people.

Government Regulation The number of radio broadcasts grew quickly in the 1920s, but there was no regulation of frequency use or transmitter strength. The result was a crowded radio band of overlapping signals. To remedy this, the U.S. government created the Federal Communications Commission (FCC) in 1934 to regulate the spreading use of the broadcast spectrum. The FCC licenses broadcasters and regulates the location and transmitting strength, or range, stations have in an effort to prevent interference from nearby signals.

4. International Telecommunications Networks

In order to provide overseas telecommunications, people had to develop networks that could link widely separated nations. The first networks to provide such linkage were telegraph networks that used undersea cables, but these networks could provide channels for only a few simultaneous communications. Shortwave radio also made it possible for wireless transmissions of both telegraphy and voice over very long distances.

To take advantage of the capability of satellites to provide telecommunications service, companies from all over the world pooled resources and shared risks by creating a cooperative known as the International Telecommunications Satellite Organization, or Intelsat, in 1964. Transoceanic satellite telecommunications first became possible in 1965 with the successful launch of Early Bird, also known as Intelsat 1. Intelsat 1 provided the first international television transmission and had the capacity to handle one television channel along with 240 simultaneous telephone calls.

Intelsat has expanded and diversified to meet the global and regional satellite requirements of over 200 nations and territories. In response to private satellite ventures entering the market, the managers of Intelsat have sought to convert the cooperative into a corporation better able to compete with these emerging companies. A separate cooperative known as the International Mobile Satellite Organization (Inmarsat) primarily provides service to oceangoing vessels, but it has expanded operations to include service to airplanes and users in remote land areas not served by cellular radio or wireline services. Inmarsat also seeks to become a private corporation, because of competition from private satellite ventures.

5. Current Developments

Personal computers have pushed the limits of the telephone system as more and more complex computer messages are being sent over telephone lines, and at rapidly increasing speeds. This need for speed has encouraged the development of digital transmission technology. Innovations in fiber-optic technology will hopefully keep up with the growing use of personal computers for telecommunications. The next generation of cellular telephones, pagers, and televisions will also benefit from the speed and clarity of digital telecommunications.

Telecommunications and information technologies are merging and converging. This means that many of the devices that we associate with only one function may evolve into more versatile equipment. This convergence is already happening in various fields. Some telephones and pagers are able to store not only phone numbers but also names and personal information about callers. Advanced phones with keyboards and small screens are now in development that can access the Internet and send and receive e-mail. Personal computers can now access information and video entertainment and are in effect becoming a combined television set and computer terminal. Television sets, which we currently associate with broadcast and cable-delivered video programming, are able to gain access to the Internet through add-on appliances. Future modifications and technology innovations may blur the distinctions between appliances even more.

Convergence of telecommunications technologies will also trigger a change in the content available and the composition of the content provider. Both television and personal computers will be incorporating new multimedia, interactive, and digital features. For example, an entertainment program might have on-screen pointers to World Wide Web pages containing more information about the actors. In the near term, before the actualization of a fully digital telecommunications world, devices like modems will still be necessary to provide an essential link between the old analog world and the upcoming digital one.


А также другие работы, которые могут Вас заинтересовать

41697. Определение затрат мощности на перемешивание в аппарате с мешалкой 4.72 MB
  При увеличении скорости движения происходит отрыв пограничного слоя от поверхности тела в точках где скорость жидкости является наибольшей например у кромок вертикальной пластины и образование турбулентного кормового следа за движущимся телом. Начало отрыва пограничного слоя характеризуется резким возрастанием сопротивления среды движению тела. Описание экспериментальной установки Лабораторная установка схема которой изображена на рисунке 4 состоит из циклона 4 внутренний диаметр циклона 02м размер входного патрубка 013005 м...
41698. Позиционные системы счисления. Перевод чисел из одной позиционной системы счисления в другую. Арифметические операции с числами в позиционных системах счисления 48.78 KB
  Перевод чисел из одной позиционной системы счисления в другую. Арифметические операции с числами в позиционных системах счисления. Цели работы: Освоение алгоритма перевода чисел из произвольной системы счисления в десятичную систему счисления.
41700. Изучение приборов для измерения давления. Определение гидростатического давления 370.32 KB
  Определение гидростатического давления Цель работы: освоение способов измерения гидростатического давления. Приборы для измерения давления Методы измерения гидростатического давления так же разнообразны как и конструкции приборов предназначенных для этого. Приборы для измерения давления носят общее название манометров.
41701. Операционная система Linux. Работа в консольном режиме 907.12 KB
  Чтобы выполнить команду ее надо записать после приглашения и нажать Enter. Тогда следует дать команду cl 2009. Если написать команду без параметра то она выдаст пустую строку. Если команду ls использовать с ключом l то вывод будет более информативным.
41702. Построение паспорта прочности породы. Определение сцепления и угла внутреннего трения 43.68 KB
  Произвести краткую статическую обработку результатов испытаний; Построить паспорт прочности горной породы в координатах σ – τ; По паспорту прочности определить сцепление и угол внутреннего трения породы. Результаты испытаний представляют собой ряд равноточных измерений поэтому их обработку ведем в следующей последовательности: Определяем среднее значение σр σсж результатов испытаний: ...
  Целью работы является изучение файловой структуры диска и основных ее элементов, основных сервисных функции операционной системы MS-DOS и приобретение практических навыков их использования.
  Я исследовал токи, напряжения и мощности в цепи постоянного тока с помощью пакета прикладных программ PSpise. Так же я составили описание схемы на внутреннем языке PSpice, предварительно заменив источники тока, источниками напряжений и упростил схему.