TELECOMMUNICATIONS SYSTEMS

TELECOMMUNICATIONS SYSTEMS

AIM:

To recognize the English technical terms related to telecommunications systems;

OBJECTIVES:

On successfully completing this unit the student should be able to:

identify correctly the terms defining all types of telecommunications systems;

recognise the specific terms related to the telecommunications devices used in each system;

describe the main components of each system;

identify the types of equipment used for different types of transmission;

describe the processes that underlie the operation of each type of device;

assimilate at least 30 terms specific of telegraph-, telephone-, teletype-, telex-, and facsimile transmission;

KEY TERMS:

switching station, technology, high-speed broadband connections, multimedia information, telegram, receiving party, wireless telegraphy, land-based station, voice communications, data communications, low-voltage direct current, network switches, microwave relay station, text delivery system, teletype system, telex system, facsimile machine (fax machine), terminal, telex keyboard, graphics, optical scanner, coded information, printer.

Telecommunications Systems

9.1. INTRODUCTION

Individual people, businesses, and governments use many different types of telecommunications systems. Some systems, such as the telephone system, use a network of cables, wires, and switching stations for point-to-point communication. Other systems, such as radio and television, broadcast radio signals over the air that can be received by anyone who has a device to receive them. Some systems make use of several types of media to complete a transmission. For example, a telephone call may travel by means of copper wire, fibre-optic cable, and radio waves as the call is sent from sender to receiver. All telecommunications systems are constantly evolving as telecommunications technology improves. Many recent improvements, for example, offer high-speed broadband connections that are needed to send multimedia information over the Internet.

9.2. TELEGRAPH

Telegraph services use both wire line and wireless media for transmissions. Soon after the introduction of the telegraph in 1844, telegraph wires spanned the country. Telegraph companies maintained a system of wires and offices located in numerous cities. A message sent by telegraph was called a telegram. Telegrams were printed on paper and delivered to the receiving party by the telegraph company. With the invention of the radio in the early 1900s, telegraph signals could also be sent by radio waves. Wireless telegraphy made it practical for ocean-going ships as well as aircraft to stay in constant contact with land-based stations.

9.3. TELEPHONE

The telephone network also uses both wire line and wireless methods to deliver voice communications between people, and data communications between computers and people or other computers. The part of the telephone network that currently serves individual residences and many businesses operates in an analogue mode, uses copper wires, and relays electronic signals that are continuous, such as the human voice. Digital transmission via fibre-optic cables is now used in some sections of the telephone network that send large amounts of calls over long distances. However, since the rest of the telephone system is still analogue, these digital signals must be converted back to analogue before they reach users. The telephone network is stable and reliable, because it uses its own wire system that is powered by low-voltage direct current from the telephone company. Telephone networks modulate voice communications over these wires. A complex system of network switches maintains the telephone links between callers. Telephone networks also use microwave relay stations to send calls from place to place on the ground. Satellites are used by telephone networks to transmit telephone calls across countries and oceans.

9.4. TELETYPE, TELETEXT AND FACSIMILE TRANSMISSION

Teletype, telex, and facsimile transmission are all methods for transmitting text rather than sounds. These text delivery systems evolved from the telegraph. Teletype and telex systems still exist, but they have been largely replaced by facsimile machines, which are inexpensive and better able to operate over the existing telephone network. The Internet increasingly provides an even more inexpensive and convenient option. The teletype, essentially a printing telegraph, is primarily a point-to-multipoint system for sending text. The teletype converts the same pulses used by telegraphs into letters and numbers, and then prints out readable text. It was often used by news media organizations to provide newspaper stories and stock market data to subscribers. Telex is primarily a point-to-point system that uses a keyboard to transmit typed text over telephone lines to similar terminals situated at individual company locations.

Facsimile transmission now provides a cheaper and easier way to transmit text and graphics over distances. Fax machines contain an optical scanner that converts text and graphics into digital, or machine-readable, codes. This coded information is sent over ordinary analogue telephone lines through the use of a modem included in the fax machine. The receiving fax machines modem demodulates the signal and sends it to a printer also contained in the fax machine.

	You may want to go back to the key words listed at the beginning of the unit and check that you are familiar with each one. Give their Romanian equivalents (if necessary, you can use the glossary provided at the end of the textbook).

EXERCISES

A. READING

The purpose of the following exercises is to develop reading strategies and reinforce topic related vocabulary, not to check background knowledge.

A.1. Having read the text, decide whether the information given in the statements below is true (T) or false (F). Correct the false statements (the specifications in brackets refer o the section in the text where the answer can be found):

1. Individual people, businesses, and governments use the same type of telecommunications systems.

2. Some systems, such as the telephone system, use a network of cables, wires, and switching stations for point-to-multipoint communication.

3. Some systems make use of several types of media to complete a transmission.

4. Telegraph services use both wire line and wireless media for transmissions.

5. Wire line telegraphy made it practical for ocean-going ships as well as aircraft to stay in constant contact with land-based stations.

6. The part of the telephone network that currently serves individual residences and many businesses operates in an analogue mode, uses copper wires, and relays electronic signals that are continuous, such as the human voice.

7. The telephone network is stable and reliable, because it uses its own wire system that is powered by high-voltage alternating current from the telephone company.

8. Teletype, telex, and facsimile transmission are all methods for transmitting sounds rather than text.

9. Fax machines contain an optical scanner that converts text and graphics into digital, or machine-readable, codes.

10. The receiving fax machines modem demodulates the signal and sends it to a printer outside the fax machine.

A.2. Fill in the following table with information about telecommunications systems given in the text. Some of the spaces may remain blank, as the information is not given.

Table 9.1.

B. VOCABULARY WORK

The purpose of the following exercises is to promote the acquisition of new lexical items by providing collocations, terms followed by prepositions lexical sets and translations of the terms considered relevant to the topic.

B.1. Match each of the terms in column A with a word in column B:

A B

B.2. Fill in the gaps in the following sentences with the terms randomly listed below:

List 9.1.

aircraft , network, fibre-optic cable, land-based, broadcast, wireless, ships, copper wire, to receive, digital, sender, radio waves, via, voice, wire line, optic;

Text 9.1.

Other systems, such as radio and television, ______radio signals over the air that can be received by anyone who has a device ________them.

For example, a telephone call may travel by means of ________, ________, and _______as the call is sent from _______to receiver.

Wireless telegraphy made it practical for ocean-going _____as well as ________to stay in constant contact with ________stations.

The telephone network also uses both ________ and________methods to deliver _______communications between people, and data communications between computers and people or other computers.

________transmission via fibre-______ cables is now used in some sections of the telephone ______that send large amounts of calls over long distances.

C. LANGUAGE FOCUS: QUANTIFIERS

The purpose of the following exercises is to develop language awareness in terms of quantifiers and their use with countable nouns and uncountable nouns.

C.1. Look at the list below and decide which quantifier is suitable in the given context:

List 9.2.

1. Individual people, businesses, and governments use________different types of telecommunications systems.

2. ________systems make use of several types of media to complete a transmission.

3. ______ recent improvement, for example, offers high-speed broadband connections that are needed to send multimedia information over the Internet.

4. The telephone network also uses both wire line and wireless methods to deliver voice communications between people, and ___________data communications between computers and people or other computers.

5.__________coded information is sent over _________ordinary analogue telephone lines through the use of a modem included in the fax machine.

C.2. Enter the following terms under the appropriate heading in the table below:

List 9.3.

information, data, knowledge, advance, progress, development, cooper, fibre-optics, medium, technology, feature, advantage, disadvantage, improvement, increase, decrease;

Table 9.3.

D. TRANSLATION

The purpose of this exercise is to develop translating skills.

D.1. Translate the following sentences into English:

1. Unele sisteme utilizeaza mai multe tipuri de medii de transmisie.

2. Spre exemplu, un apel telefonic poate fi transmis prin intermediul cablurilor de cupru, al cablurilor de fibra optica, si al undelor radio succesiv.

Acea parte a retelei de telefonie care deserveste locuinte sau sedii de firma functioneaza pe principiul analogic utilizand cabluri de cupru.

E. SPEAKING

The purpose of these exercises is to develop speaking skills with a focus on describing several telecommunications systems, their reliability and operation principles.

E.1. Presentation

Make a brief presentation of the telephone system.

(Make sure you include information about the performance, reliability, network, transmission media, type of data transmission, devices and components, operation principles and possible future development in the field).