Telecommunications 13742 Essay Example

information for transmission by converting it from a form

that the device uses (such as a clustered or parallel arrangement of electronic

bits of information) to a form that the transmission line uses (such as, usually,

a serial arrangement of electronic bits). Most transmitters are an integral

element of the sending device. A cable interface, as the name indicates,

connects a device to a cable. It converts the transmitted signals from the form

required by the device to the form required by the cable. Most cable interfaces

are also an integral element of the sending device. A modem converts digital

signals to and from the modulated form required by the telephone line to the

demodulated form that the device itself requires. Modems transmit data through a

telephone line at various speeds, which are measured in bits per second (bps) or

as signals per second (baud). Modems can be either integral or external units.

An external unit must be connected by cable to the sending device. Most modems

can dial a telephone number or answer a telephone automatically.

Software

Among the different kinds of software are file-transfer, host, and network

programs. File-transfer software is used to transmit a data file from one device

to another. Host software identifies a host computer as such and controls the

flow of data among devices connected to it. Network software allows devices in a

computer network to transmit information to one another.

Applications

Three major categories of telecommunication applications can be discussed here:

host-terminal, file-transfer, and computer-network communications.

Host-Terminal

In these types of communications, one computeraˆ”the host computeraˆ”is connected to

one or more terminals. Each terminal transmits data to or

receives data from the

host computer. For example, many airlines have terminals that are located at the

desks of ticket agents and connected to a central, host computer. These

terminals obtain flight information from the host computer, which may be located

hundreds of kilometers away from the agent's site. The first terminals to be

designed could transmit data only to or from such host computers. Many terminals,

however, can now perform other functions such as editing and formatting data on

the terminal screen or even running some computer programs. Manufacturers label

terminals as "dumb," "smart," or "intelligent" according to their varying

capabilities. These terms are not strictly defined, however, and the same

terminal might be labeled as dumb, smart, or intelligent depending upon who is

doing the labeling and for what purposes.

File-Transfer

In file-transfer communications, two devices are connected: either two computers,

two terminals, or a computer and a terminal. One device then transmits an entire

data or program file to the other device. For example, a person who works at

home might connect a home computer to an office computer and then transmit a

document stored on a diskette to the office computer. An outgrowth of file

transfer is electronic mail. For example, an employee might write a document

such as a letter, memorandum, or report on a computer and then send the document

to another employee's computer.

Computer-Network

In computer-network communications, a group of devices is interconnected so that

the devices can communicate and share resources. For example, the branch-office

computers of a company might be interconnected so that they can route

information to one another quickly. A company's computers might also

be

interconnected so that they can all share the same hard disk. The three kinds of

computer networks are local area networks (LAN), private branch exchange (PBX)

networks, and wide-area networks (WAN). LANs interconnect devices with a group

of cables; the devices communicate at a high speed and must be in close

proximity. A PBX network interconnects devices with a telephone switching

system; in this kind of network, the devices must again be in close proximity.

In wide-area networks, on the other hand, the devices can be at great distances

from one another; such networks usually interconnect devices by means of

telephone.

Telecommunication Services

Public telecommunication services are a relatively recent development in

telecommunications. The four kinds of services are network, information-

retrieval, electronic-mail, and bulletin-board services.

Network

A public network service leases time on a WAN, thereby providing terminals in

other cities with access to a host computer. Examples of such services include

Telenet, Tymnet, Uninet, and Datapac. These services sell the computing power of

the host computer to users who cannot or do not wish to invest in the purchase

of such equipment.

Information-Retrieval

An information-retrieval service leases time on a host computer to customers

whose terminals are used to retrieve data from the host. An example of this is

CompuServe, whose host computer is accessed by means of the public telephone

system. This and other such services provide general-purpose information on news,

weather, sports, finances, and shopping. Other information-retrieval services

may be more specialized. For example, Dow Jones News Retrieval Services provide

general-purpose information on financial news and quotations, corporate-earning

estimates, company disclosures, weekly economic survey updates, and Wall Street

Journal highlights.

Newsnet provides information from about 200 newsletters in

30 different industries; Dialog Information Services, BRS Bibliographic

Retrieval Services, and Orbit Information Retrieval Services provide library

information; and Westlaw provides legal information to its users. See Database.

Electronic-Mail

By means of electronic mail, terminals transmit documents such as letters,

reports, and telexes to other computers or terminals. To gain access to these

services, most terminals use a public network. Source Mail (available through

The Source) and EMAIL (available through CompuServe) enable terminals to

transmit documents to a host computer. The documents can then be retrieved by

other terminals. MCI Mail Service and the U.S. Postal ECOM Service (also

available through The Source) let terminals transmit documents to a computer in

another city. The service then prints the documents and delivers them as hard

copy. ITT Timetran, RCA Global Communications, and Western Union Easylink let

terminals send telexes to other cities.

Bulletin-Board

By means of a bulletin board, terminals are able to facilitate exchanges and

other transactions. Many bulletin boards do not charge a fee for their services.

Users of these services simply exchange information on hobbies, buy and sell

goods and services, and exchange computer programs.

Ongoing Developments

Certain telecommunication methods have become standard in the telecommunications

industry as a whole, because if two devices use different standards they are

unable to communicate properly. Standards are developed in two ways: (1) the

method is so widely used that it comes to dominate; (2) the method is published

by a standard-setting organization. The most important organization in this

respect is the International Telecommunication Union, a specialized agency of

the United Nations, and one of its operational entities,

the International

Telegraph and Telephone Consultative Committee (CCITT). Other organizations in

the area of standards are the American National Standards Institute, the

Institute of Electrical Engineers, and the Electronic Industries Association.

One of the goals of these organizations is the full realization of the

integrated services digital network (ISDN), which is projected to be capable of

transmitting through a variety of media and at very high speeds both voice and

nonvoice data around the world in digital form.

Other developments in the industry are aimed at increasing the speed at which

data can be transmitted. Improvements are being made continually in modems and

in the communications networks. Some public data networks support transmission

of 56,000 bits per second (bps), and modems for home use (see Microcomputer) are

capable of as much as 28,800 bps.

Introduction

When a handful of American scientists installed the first node of a new computer

network in the late 60's, they could not know by any chance what phenomenon they

had launched. They were set a challenging task to develop and realise a

completely new communication system that would be either fully damage-resistant

or at least functional even if an essential part of it was in ruins, in case the

Third World War started. The scientists did what they had been asked to. By 1972

there were thirty-seven nodes already installed and ARPANET (Advanced Research

Projects Agency NET), as the system of the computer nodes was named, was working

(Sterling 1993). Since those "ancient times", during which the network was used

only for national academic and military purposes (Sterling 1993), much of the

character of the network has changed. Its today

users work in both commercial

and non-commercial branches and not just in academic and governmental

institutions. Nor is the network only national: it has expanded to many

countries around the world, the network has become international and in that way

it got its name. People call it Internet.

The popularity of this new phenomenon is rising rapidly, almost beyond belief.

In January 1994 there were an estimated 2 million computers linked to the

Internet. However, this is nothing compared to the number from last year's

statistics. At the end of 1995, 10 million computers with 40-50 million users

were assumed to be connected to the network-of-networks. If it goes on like this,

most personal computers will be wired to the network at the end of this century

(Internet Society 1996).

The Internet is phenomenal in many ways. One of them is that it connects people

from different nations and cultures. The network enables them to communicate,

exchange opinions and gain information from one another. As each country has its

own national language, in order to communicate and make themselves understood in

this multilingual environment the huge number Internet users need to share a

knowledge of one particular language, a language that would function as a lingua

franca. On the Internet, for various reasons, the lingua franca is English.

Because of the large number of countries into which the Internet has spread and

which bring with them a considerable variety of languages English, for its

status of a global language, has become a necessary communication medium on the

Internet. What is more, the position of English as the language of the network

is strengthened by the

explosive growth of the computer web as great numbers of

new users are connecting to it every day.

Internet, in computer science, an open interconnection of networks that enables

connected computers to communicate directly. There is a global, public Internet

and many smaller-scale, controlled-access internets, known as enterprise

internets. In early 1995 more than 50,000 networks and 5 million computers were

connected via the Internet, with a computer growth rate of about 9 percent per

month.

Services

The public Internet supports thousands of operational and experimental services.

Electronic mail (e-mail) allows a message to be sent from one computer to one or

more other computers. Internet e-mail standards have become the means of

interconnecting most of the world's e-mail systems. E-mail can also be used to

create collaborative groups through the use of special e-mail accounts called

reflectors, or exploders. Users with a common interest join a mailing list, or

alias, and this account automatically distributes mail to all its members. The

World Wide Web allows users to create and use point-and-click hypermedia

presentations. These documents are linked across the Internet to form a vast

repository of information that can be browsed easily. Gopher allows users to

create and use computer file directories. This service is linked across the

Internet to allow other users to browse files. File Transfer Protocol (FTP)

allows users to transfer computer files easily between host computers. This is

still the primary use of the Internet, especially for software distribution, and

many public distribution sites exist. The Usenet service allows users to

distribute news messages automatically among thousands of structured newsgroups.

Telnet allows users to log in to another computer from

a remote location. Simple

Network Management Protocol (SNMP) allows almost any Internet object to be

remotely monitored and controlled.

Connection

Internets are constructed using many kinds of electronic transport media,

including optical fiber, telephone lines, satellite systems, and local area

networks. They can connect almost any kind of computer or operating system, and

they are self-aware of their capabilities. An internet is usually implemented

using international standards collectively called Transmission Control

Protocol/Internet Protocol (TCP/IP). The protocols are implemented in software

running on the connected computer. Most computers connected to the internet are

called hosts. Computers that route data, or data packets, to other computers are

called routers. Networks and computers that are part of the global Internet

possess unique registered addresses and obtain access from Internet service

providers. There are four ways to connect to the public Internet: by host,

network, terminal, or gateway access. Host access is usually done either with

local area networks or with the use of telephone lines and modems combined with

Internet software on a personal computer. Host access allows the attached

computer to fully interact with any other attached computeraˆ”limited only by the

bandwidth of the connection and the capability of the computer. Network access

is similar to host access, but it is usually done via a leased telephone line

that connects to a local or wide area network. All the attached computers can

become Internet hosts. Terminal access is usually done via telephone lines and

modems combined with terminal-emulation software on a personal computer. It

allows interaction with another computer that is an Internet host. Gateway

access is similar to terminal access but is provided via on-line or

similar

proprietary services, or other networks such as Bitnet, Fidonets, or UUCP nets

that allow users minimally to exchange e-mail with the Internet.

Development

The Internet technology was developed principally by American computer scientist

Vinton Cerf in 1973 as part of a United States Department of Defense Advanced

Research Projects Agency (DARPA) project managed by American engineer Robert

Kahn. In 1984 the development of the technology and the running of the network

were turned over to the private sector and to government research and scientific

agencies for further development. Since its inception, the Internet has

continued to grow rapidly. In early 1995, access was available in 180 countries

and there were more than 30 million users. It is expected that 100 million

computers will be connected via the public Internet by 2000, and even more via

enterprise internets. The technology and the Internet have supported global

collaboration among people and organizations, information sharing, network

innovations, and rapid business transactions. The development of the World Wide

Web is fueling the introduction of new business tools and uses that may lead to

billions of dollars worth of business transactions on the Internet in the future.

In the Internet nowadays, the majority of computers are from the commercial

sphere (Vrabec 1996). In fact, the commercialisation of the network, which has

been taking place during the last three or four years, has caused the recent

boom of the network, of the WWW service in particular (Vrabec 1996). It all

started in the network's homeland in 1986, when ARPANET was gradually replaced

by a newer and technologically better built network called NSFNET. This network

was more open to private and

commercial organisations (Vrabec 1996) which,

realising the potential of the possible commercial use of the Internet, started

to connect themselves to the network.

There are several possibilities how commercial organisations can benefit from

their connection to the English-speaking Internet. Internet users are supposed

to be able to speak and understand English, and actually most of them do. With

the rapidly rising number of users, the network is a potential world market

(Vrabec 1996) and English will be its important tool. The status of English as a

world language, or rather its large number of people who are able to process and

use information in English, already enables commercial organisations to present

themselves, their work and their products on the Internet. Thanks to English and

the Internet companies can correspond with their partners abroad, respond to any

question or give advice on any problem that their international customers can

have with their products almost immediately (Vrabec 1996). Considering the fact

that many of the biggest, economically strongest and influential organisations

are from the USA or other native English speaking countries, the

commercialisation has very much reinforced the use of English on the Internet.

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Cepek, Ales and Vrabec, Vladimir 1995 Internet :-) CZ, Praha, Grada Demel, Jiri

1995 Internet pro zacatecniky, Praha, NEKLAN Falk, Bennett 1994 InternetROADMAP,

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Triumph Of English" The Times, May 1995 Philipson, Robert 1992 Linguistic

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