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English for Telecommunications and Radio Technologies in Rail Transport.docx
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Convergence on digital transmission

  1. Before reading the text discuss the following questions:

    - What is the role of digital transmission in modern life?

    - What digital devices are used to transmit information? Why are they so popular?

  1. Read the words and learn them by heart:

Bandwidth (n) – ширина полосы частот, пропускная способность, полоса пропускания канала

Circuit (n) – цепь

Circuit-switching (n) – коммутация каналов

Coaxial (adj) – коаксиальны, совпадающий осями, имеющий общую ось

Compressed (adj) – сжатый

Convergence [kənˈvɜːdʒ(ə)ns] (n) – взаимодействие, взаимопроникновение, конвергенция

Copper (adj) –медный

Envelop (n) – конверт

Error-checking –проверка ошибок

Exceed (v) – превышать

Fiber-optic (adj) – оптоволоконный

Frequency division multiplexing — мультиплексирование с разделением частот

Implementation (n) – внедрение, реализация, осуществление

Multiplexing (n) – уплотнение каналов связи, многоканальная передача (информации), мультиплексирование

Packet switching device – устройство коммутации пакетов

Protocol (n) – протокол

Receiver (n) – получатель

Router (n) – маршрутизатор, роутер

Semi-permanent (adj) - полупостоянный

Sender (n) – отправитель

TCP (Transmission Control Protocol) – протокол управления передачей данных

Two-way (adj) – двусторонний

UNIX – операционная система UNIX

Zip code (n) – почтовый индекс

  1. Read the text and make a summary: convergence on digital transmission

Many long-distance companies are implementing a data networking approach, now called an IP standard from the UNIX TCP/IP protocol suite. Data, voice, and video are being sent digitally as packets of data, rather than as parts of an analog frequency. The digital approach promises faster, cheaper, and better telecommunications services; it is especially well suited to fiber-optic wiring. The widespread popularity of digital devices suggests that digital data networks make the most sense. In long-distance and wireless activity the amount of data now exceeds the amount of voice transmission, moving both voice and data to IP networking.

Cable-TV transmissions employ frequency division multiplexing to continuously send many channels one-way to TV tuners. Data and voice transmissions are two-way, often short bursts from sender to receiver. This adds considerable complexity, as TCI and Time Warner discovered during the implementation of phone and Internet services over their coaxial cables.

Phone conversations are semi-permanent sessions between sender and receiver. The phone companies use circuit-switching technology to connect the two parties by establishing a circuit, or connection, for the duration of the call for the exclusive use of the two parties. But that is preceded by establishing the link or circuit through the local switching center, the long-distance carrier, and another switching center. Here again the wire capacity is broken up into circuits using frequency division multiplexing. The traditional T-1 line provides twenty-four separate telephone circuits over copper wire; each circuit is equivalent to 64,000 bits per second digital channel.

Data network standards were established as millions of local area networks were created in businesses all over the world. Data is sent and received in packets, called “datagrams,” defined by protocols, such as the dominant IP protocol. The packets have a “to” address, a “from” address, considerable digital data, and error-checking data; each packet also indicates that it is one of many in a group, to be assembled by the receiving computer. Data networks operate like the mail delivery system in that data is put into envelops. The “to” and “from” addresses contain both a single individual address as well as the area's zip code. Trucks (wires) take all the mail to central hubs, where it is again sorted and sent to the right zip code post office which delivers the envelop to the right home address. Data networks use packet switching devices, typically routers, to truck the packets from router to router along the path.

Packet switching is much more efficient for little e-mail messages or slow phone conversations. With packet switching, an exclusive circuit is not necessary as the entire bandwidth is always open to accept packets. The standard for fiber optic transmission is 2.5 Gbps (2.5 billion bits per second), so very large amounts of information can be moved in the blink of an eye. Compressed video and compressed music take up lots of bandwidth; a CD holds 600 million bytes (4.8 billion bits), but data can be compressed by half into roughly 2.5 billion bits, and sent and received in a second.

https://www.encyclopedia.com/social-sciences-and-law/economics-business-and-labor/businesses-and-occupations/telecommunications