Telecoms Book 07

74
English for Telecoms Industry. English Section. 2007. 1 Môc lôc Trang Môc lôc Lêi nãi ®Çu 1 3 Unit 1 Computer Communications Presentation 1. Passive Voice Presentation 2. The Use of Modal Verbs 4 8 11 Unit 2 Public Data Network Presentation 1. Relative Clause Presentation 2. Expressing Contrasting Ideas 13 17 19 Unit 3 Public Communication Network Presentation 1. Gerunds (V-ING form) Presentation 2. Expressing Concession 22 25 26 Unit 4 Electronic Exchanges Presentation 1. Comparisons of Adjectives Presentation 2. Present Perfect vs Simple Past 28 32 34 Unit 5 Transmission Systems Presentation 1. Reduced Adjective Clauses Presentation 2. Double Comparatives 36 40 42 Unit 6 Radio Communications Presentation 1. Past Participle Presentation 2. Phrasal Verbs 44 48 50 Unit 7 Switching Presentation 1. Time Clauses Presentation 2. Expressing Quantity and Amount 52 56 58 Unit 8 Electronical Telecommunications System Presentation 1. Noun Formation Presentation 2. Expressing Purposes and Reasons 61 65 67

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anh văn chuyên ngành

Transcript of Telecoms Book 07

Page 1: Telecoms Book 07

English for Telecoms Industry. English Section. 2007. 1

Môc lôc

Trang

Môc lôc

Lêi nãi ®Çu

1

3

Unit 1 Computer Communications

Presentation 1. Passive Voice

Presentation 2. The Use of Modal Verbs

4

8

11

Unit 2 Public Data Network

Presentation 1. Relative Clause

Presentation 2. Expressing Contrasting Ideas

13

17

19

Unit 3 Public Communication Network

Presentation 1. Gerunds (V-ING form)

Presentation 2. Expressing Concession

22

25

26

Unit 4 Electronic Exchanges

Presentation 1. Comparisons of Adjectives

Presentation 2. Present Perfect vs Simple Past

28

32

34

Unit 5 Transmission Systems

Presentation 1. Reduced Adjective Clauses

Presentation 2. Double Comparatives

36

40

42

Unit 6 Radio Communications

Presentation 1. Past Participle

Presentation 2. Phrasal Verbs

44

48

50

Unit 7 Switching

Presentation 1. Time Clauses

Presentation 2. Expressing Quantity and Amount

52

56

58

Unit 8 Electronical Telecommunications System

Presentation 1. Noun Formation

Presentation 2. Expressing Purposes and Reasons

61

65

67

Page 2: Telecoms Book 07

English for Telecoms Industry. English Section. 2007. 2

Further Reading

Reading 1

Reading 2

Reading 3

69

71

73

S¸ch tham kh¶o 76

Page 3: Telecoms Book 07

English for Telecoms Industry. English Section. 2007. 3

Lêi nãi ®Çu

Trong nh÷ng n¨m ®Çu thÕ kû 21 nµy, ngµnh ViÔn th«ng §iÖn tö ®ang ph¸t triÓn v­ît bËc,

víi nh÷ng ph¸t minh, tiÕn bé khoa häc ra ®êi trong tõng phót tõng gi©y, gãp phÇn ®Èy

nhanh tèc ®é t¨ng tr­ëng vµ ph¸t triÓn kinh tÕ trªn toµn cÇu vµ trong tõng quèc gia.

TiÕng Anh chuyªn ngµnh ViÔn th«ng §iÖn tö tõ l©u ®· trë thµnh mét nhu cÇu cÊp thiÕt ®èi

víi c¸c nhµ qu¶n lý, khai th¸c vµ cung cÊp dÞch vô viÔn th«ng ë ViÖt Nam vµ lµ hµnh

trang kh«ng thÓ thiÕu ®èi víi c¸c c¸n bé ®ang nghiªn cøu vµ c«ng t¸c trong lÜnh vùc nµy.

Nh»m trî gióp viÖc nghiªn cøu vµ häc tËp chuyªn m«n cña sinh viªn ngµnh ViÔn th«ng

§iÖn tö, ®Æc biÖt lµ chuyªn ngµnh Kü thuËt ViÔn th«ng cña tr­êng ®¹i häc Giao th«ng

VËn t¶i, nhãm biªn so¹n xin tr©n träng giíi thiÖu tËp bµi gi¶ng TiÕng Anh chuyªn ngµnh

Kü thuËt ViÔn th«ng.

TËp bµi gi¶ng ®­îc biªn so¹n trªn c¬ së tËp hîp vµ tuyÓn chän nh÷ng m¶ng ®Ò tµi chÝnh

th­êng ®­îc nh¾c ®Õn trong ngµnh KTVT nh­ hÖ thèng viÔn th«ng, hÖ thèng m¹ng,

truyÒn dÉn, chuyÓn m¹ch v.v. Víi thêi l­îng 75 tiÕt (5 §VHT), tËp bµi gi¶ng ®­îc thiÕt

kÕ víi hai néi dung chÝnh trong mçi bµi: Bµi ®äc hiÓu TACN vµ phÇn cñng cè kiÕn thøc

ng÷ ph¸p tiÕng Anh. V× vËy, nhãm biªn so¹n kh«ng thÓ ®Ò cËp hÕt tÊt c¶ c¸c chuyªn ®Ò

kh¸c nhau cña chuyªn ngµnh. Tuy nhiªn, sinh viªn cã thÓ t×m thÊy trong tËp bµi gi¶ng nµy

nh÷ng th«ng tin bæ Ých vÒ lÞch sö ph¸t triÓn vµ h×nh thµnh còng nh­ ho¹t ®éng cña mét sè

hÖ thèng chÝnh trong ngµnh ViÔn th«ng trªn thÕ giíi. §Æc biÖt, tËp bµi gi¶ng cung cÊp nÒn

t¶ng c¬ b¶n cña TACN KTVT cïng c¸c thuËt ng÷ chuyªn dông, nh»m gióp sinh viªn h×nh

thµnh kü n¨ng ng«n ng÷ ®Ó tù häc tËp vµ nghiªn cøu sau nµy. §©y chÝnh lµ môc ®Ých biªn

so¹n cña tËp bµi gi¶ng nµy.

Nhãm biªn so¹n bµi gi¶ng gåm: Th.s. Bïi Thuý Hång, Th.s. Ph¹m ThÞ Thu Thuû v

Th.s. NguyÔn ThÞ Thu H­¬ng (chñ biªn).

Nh©n ®©y, chóng t«i xin bµy tá sù c¶m ¬n ch©n thµnh tíi c¸c gi¸o viªn bé m«n KTVT,

phßng §µo t¹o, Bé m«n Anh v¨n vµ c¸c phßng ban liªn quan ®· gióp ®ì nhiÖt t×nh chóng

t«i ®Ó cã thÓ biªn so¹n ®­îc mét bµi gi¶ng cã chÊt l­îng vµ sím ®Õn tay ng­êi ®äc.

Chóng t«i còng rÊt mong nhËn ®­îc sù ®ãng gãp ý kiÕn x©y dùng tõ c¸c ®ång nghiÖp ®Ó

c¶i tiÕn vµ n©ng cao h¬n n÷a chÊt l­îng cña bµi gi¶ng nµy.

Xin ch©n thµnh c¶m ¬n.

Nhãm biªn so¹n

Page 4: Telecoms Book 07

English for Telecoms Industry. English Section. 2007. 4

unit one

Computer Communications

Part I. Reading Comprehension

Read the passage and do the following tasks.

The present status of telecommunications is a result of a long evolution through more

than a hundred years. It is interesting to note that the old telegraph system used digital

transmission. When, many years later, telephony was introduced, analogue transmission

was used. Telex, on the other hand, worked with a digital technique while video

transmission in principle uses analogue transmission. Data communications is digital and

a transition is now taking place where all services, voice, text, data and picture will be

integrated in a basic digital network. This digital network will be an ideal carrier of data

communications and will promote the growth of such communications.

The development of data communications depends, to a great extent, on the development

of data processing. So far, all the signs indicate a trend towards remote data processing,

which means a greater usage of data communications services. Indeed, a ‘marriage’ of

telecommunications and data processing will be the result. This ‘marriage’ will hopefully

result in a number of useful products. Already a range of specialized services is foreseen,

in particular in the text and picture communications field.

A number of new text services have been, or will be, introduced shortly:

Firstly, a lot of interest has been shown in Teletex which is already being introduced in

some countries. Teletex is an international service enabling subscribers to exchange

correspondence on an automatic memory-to-memory basis, via telecommunications

networks. As a successor to Telex, it will use specially adapted word processors and

electronic typewriters and enable a 3-page A4 letter to be sent almost instantaneously

from one end of the country to the other. In Britain, estimates vary of when Teletex will

be forthcoming, but meanwhile, Germany and Sweden already have systems in operation

and teletex launches are planned in France, Spain, Belgium and Canada before long.

The Telefacsimile service is well established, though faster and more advanced systems

(Group 4 types) will be introduced shortly. This service provides for the transmission and

reproduction of still pictures and printed matter. Telefax has its biggest market in Japan

where the complexity of Japanese script makes this an ideal medium of transmission.

Videotex, called Viewdata in the UK, has passed through an experimental and testing

stage and is now available in many countries. Videotex is a service enabling a subscriber

Page 5: Telecoms Book 07

English for Telecoms Industry. English Section. 2007. 5

to obtain information over the Public Switched Telecoms Network (PSTN) for

presentation in alphanumeric and/or graphic from on a VDU-usually a specially adapted

TV receiver. This service is marketed under different names in different countries. Prestel

in UK, Bildschirmtext in FRD and Telidon in Canada. Videotex subscribers may choose

to have an additional service_ electronic mailbox enabling them to send messages

directly and instantaneously to one another. The UK Viewdata system, which is an

interactive service, should not be confused with Teletext, a one-way information service

which TV companies broadcast. (In the UK two systems are available – Ceefax and

Oracle.)

Vocabulary

alphanumeric (a) ch÷ sè

analogue transmission (np) truyÒn dÉn t­¬ng tù

data processing (np) xö lý d÷ liÖu

electronic mailbox (np) hép th­ ®iÖn tö

instantaneous ( a) tøc thêi, ngay tøc th×

interactive (a) hai chiÒu, t­¬ng ®ång, t­¬ng t¸c

launch (v) tung ra

obtain (v) ®¹t ®­îc, thu ®­îc

script (n) ch÷ viÕt tay gièng ch÷ in

status (n) vÞ thÕ, t×nh tr¹ng

still picture (np) ¶nh tÜnh

transition (n) chuyÓn ®æi, chuyÓn tiÕp

trend (n) xu h­íng

Task 1. Answer the following questions about the passage.

1. What kind of transmission was used in telephony service many years ago?

................................................................................………...................................................

2. What does a trend towards ‘remote data processing’ imply?

.................................................………..................................................................................

3. What are the two features which distinguish Teletex from Telex?

..................................................……….................................................................................

4. Why is Japan such a big market for Telefax?

..............................................................................……….....................................................

5. What is the other name of ‘Viewdata’?

...............................................................................................................………....................

6. What does PSTN stand for?

..........................................……….........................................................................................

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English for Telecoms Industry. English Section. 2007. 6

Task 2. Decide if the following statements are True or False.

1. Telex uses digital transmission.

2. The development of data processing does not influence the development of data

communications.

3. The ideal carrier of data communications is the digital network in which all

services, voice, telex, data and pictures will be integrated.

4. The ‘marriage’ of telecommunications and data processing is caused by a number

of useful products.

5. Teletex is an international service that can help subscribers to communicate on an

automatic memory to memory basis.

Task 3. Classify the following services by putting a tick under Digital (D) or Analogue

(A) transmission.

Digital Analogue

Telegraphy

Telephony

Telex

Video

Data

Task 4. Use the table below to put together the definitions of products or services as e.g.

Name Classification Characteristics/ Functions

Teletex International service It enables subscribers to exchange correspondence

on an automatic memory to memory basis.

Teletex is an international service enabling (which enables) subscribers to

exchange correspondence on an automatic memory to memory basis.

Name Classification Characteristics/ Functions

1. Videotex service It enables a subscriber to obtain alphanumeric and/or

graphic information over the PSTN

2. Lasers light sources They produce light of a closely defined wavelength.

3. PCM means of transmission It involves the sampling and coding of analogue

signals.

4. Telefax new service It provides for the transmission and reproduction of

still pictures and printed matter.

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English for Telecoms Industry. English Section. 2007. 7

1. …………………………………………………..………………………………………

………………………………………………….……….………………………………

2. …………………………………………………………..………………………………

…………………………………………………………………………..………………

3. …………………………………………………………..………………………………

…………………………………………………………………………..………………

4. ………………………………………………………………………..…………………

………………………………………………………….………………………….……

Task 5. Match the Name, Classification and Characteristics to make similar definitions

orally.

1. Electronic mail

circuit switched

network

It provides a means of synchronous data

transmission

2. CCS (Common

Channel Signalling)

new service It uses one pair for performing all signalling

fuctions of one route.

3. SPC (stored

program control)

electronic

system

They enable PCM transmission to be used

further out in the local network

4. Datex method of

signalling

It provides a means of asynchronous data

transmission

5. Remote

concentrators

packet switched

network

It enables videotex subscribers to send messages

directly and instantaneously to one another

6. Nordic Public Data

Network

remote part of

an exchange

It uses data processing and computer techniques

switching

Task 6. Translate the first paragraph into Vietnamese.

...............................................................................................................................................

...............................................................................................................................................

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...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

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...................…………………………………………………………………………………

……......................................................................................................................................

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English for Telecoms Industry. English Section. 2007. 8

Part II. Language in Use

Presentation 1. passive voice

Study these sentences.

A. International traffic is carried by the Transit Network.

B. The Transit Network carries international traffic.

Both A and B are correct. The choice (A or B) depends on what you want to emphasize_

‘International traffic’ (sentence A) or ‘the Transit Network’ (sentence B).

Now look at these two sentences:

C. Additional cables are laid.

D. They lay additional cables.

C is more expressive than D. The personal subject ‘they’ in D does not add any information. In fact, it makes the important information more difficult to see.

Passives are very common in technical writing when we are more interested in facts, process, and events than in the agents/ people who do the actions.

The Passive Voice of sentences is formed as follows:

[S + BE + PII (Past Participle)]

N.B. - PII of regular verbs is formed according to the rules, i.e. V + ed

- PII of irregular verbs has different forms and needs learning by heart.

Below are concrete forms of some common verb tenses:

Present Simple am/are/is + PII

The exchanges are maintained regularly.

Present Continuous am/are/is + being + PII

A public telephone box is being installed on the corner of

the street.

Past Simple was/were + past participle

When the telephony was introduced, analogue system was

used.

Past Continuous was/were + being + past participle

Unfortunately, the VCTV3 cable was being repaired when

that big match was on.

Present Perfect Simple have/has + been + past participle

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English for Telecoms Industry. English Section. 2007. 9

The call has just been passed through the operator.

Past Perfect Simple had + been + PII

I was told that a range of specialized services had been

foreseen in the text and picture communications field.

Modal verbs can/ could/ may/ might/ must/ should + be+ PII

Local network can be divided into some parts.

PRACTICE

Ex.1. Make sentences from the table below. In some cases, you can make both an active

and a passive sentence.

E.g. You expand the central exchange. (active)

Or The central exchange is expanded. (passive)

Agent Action Object Adverbial

a. You expand the central exchange

b. The junction circuits use PCM mainly

c. SPC exchanges serve both areas

d. They install Cabinets in the local area

e. We route Traffic directly to a GSC

f. An open-wire line connect the subscriber

to the DP

g. Some people set up all non-local calls via a GSC

h. A machine dig up the road

in order to lay a

cable

i. The company site the new exchange

near the old

exchange

j. The RSS switch the call to the designated

cabinet

PCM- pulse code modulation ®iÒu biÕn m· xung

SPC - system programme controller bé ®iÒu khiÓn ch­¬ng tr×nh cña hÖ thèng

GSC- group switching centre trung t©m chuyÓn m¹ch nhãm

DP - distribution point ®iÓm ph©n phèi

RSS - remote subscriber switching chuyÓn m¹ch thuª bao xa ...............................................................................………....................................................

...............................................................................………....................................................

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..................................................................................................................................

...................................................................................................................................

...................................................................................................................................

Ex.2. Use the appropriate forms of verbs in parentheses to complete the sentences below.

1. In the trunk network, all non-local calls (set up) via a GSC and the main network.

........................................

2. In the ten-year period 1975-1985, important pilot schemes (implement) in France to assess the value and usefulness of certain networks.

.........................................

3. Indian’s first earth station (build) at Arvi towards the end of the 1960s and seven others quickly followed.

…………………………

4. Puma’s memory (use) to store messages for later transmission.

………………………….

5. Further copies can (make) by reptinting the messages from the memory in the local mode.

.........................................

6. Local Area Network (define) as transmission and switching systems that (provide) high-speed communication between devices located on a single site.

.................................

7. To reduce the number of cables, the local network usually (divide) into three parts.

…………………………….

8. A series of INTELSAT satellites (launch), the next of which was INTELSAT VI in

1986.

…………………………….

9. When we plan the facsimile transmission system, care must (take) for the use of new

services.

…………………………….

10. Recently, tests (carry) out with different solutions in most industrialized countries.

…………………………….

Page 11: Telecoms Book 07

English for Telecoms Industry. English Section. 2007. 11

Presentation 2. the use of modal verbs

Study these sentences.

A. The main advantage of radio-paging is that you can be contacted wherever you are.

B. You must, however, be above, not below ground level, for the signal will not get through if you are underground.

The words in bold cannot function themselves, but must combine with a verb either in

Passive Voice as in sentence A or in Active Voice as in sentence B to make sense. Thus,

they are called Modal Verbs or Modal Auxiliaries.

Modal Verbs include; may, might, must, can, could, will, shall, should, need, ought to

Modal Verbs generally express a speaker’s attitudes, or ‘moods’, such as advice,

permission, necessity, request, etc.

Below are some common uses of Modal Verbs in ESP setting.

Expressing POSSIBILITY

We use may or might to say that something is possible or it is quite likely to occur. We

can use them for the present or future. Could is also used to express a small possibility

(sù viÖc còng cã thÓ x¶y ra víi x¸c suÊt thÊp).

E.g. The CPU may/ might/ could be located anywhere in the network.

That tactic could be useful to promote Telefax market in other countries.

Expressing ADVICE, RECOMMENDATION and PROBABILITY

We use should and ought to to say what is the best thing or the right thing to do (giving

advice). There is no difference in meaning.

E.g. LANS ought to / should be designed on optical fibre.

VNPT should enforce stricter laws on network exploitation.

Besides, ought to and should are used to express probability (kh¶ n¨ng, x¸c suÊt cã thÓ

x¶y ra).

Expressing NECESSITY or OBLIGATION

We use must, need (and have to) to say that something is necessary or someone is

obliged to do something. In writing there is slight difference between these words. In

speech there is a certain difference. Must is normally used when the speaker personally

feels something is important for others to do and need is used when the situation makes

something necessary to do.

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English for Telecoms Industry. English Section. 2007. 12

E.g. You must install the equipment before the new exchange is put into operation.

(speaker imposes his opinions/ wants on others)

The equipment needs/ has to handle information in different forms.

(it is the principle)

Expressing PERMISSION

We use can and may to give and ask for permission.

E.g. You can/ may only export this electronic equipment if you get a special licence.

Expressing ABILITY

We use can to say that someone has an ability to do something.

E.g. No one can tap LANs.

For ability in the past, we use could (or were/ was able to).

E.g. Thanks to the automatic exchange, Almond B. Strowger could/ was able to contact

his clients directly and develop his business.

PRACTICE

Complete the following sentences with appropriate modal verbs.

1. The report ______ be finished by 6 o’clock. (obligation)

2. Your telephone _____ be installed by Friday. (probability)

3. This equipment ______ be exported to certain countries. (permission)

4. You _______ wear protective clothes at all time when working in a satellite

station. (advice)

5. We ______ not deliver until we receive the parts. (ability)

6. A LAN _____ be installed in most modern offices. (possibility)

7. The participants _____work out operational systems suitable to their own

administration. (obligation)

8. Optical fibres ______ come down in price as production expands. (probability)

9. Whatever the answers are, Videotex is here to stay and we ________adapt to it in

an appropriate way. (obligation)

10. According to the schedule, all high-rise buildings in this region _________ be

provided with TV cables by mid 2008. (probability)

Page 13: Telecoms Book 07

English for Telecoms Industry. English Section. 2007. 13

Unit two

Public Data Network

Part I. Reading comprehension

Read the passage and do the following tasks.

Public Data Networks are designed for data transmission only. They therefore avoid the

limitations of speed of transmission over the switched public telephone or telex network.

The Nordic Public Data Network is a circuit-switched type of digital network and its

basic purpose is to provide a means of synchronous data transmission.

The network consists of a number of components which are interconnected shown in

Figure 1.The Data Switching Exchange (DSE) controls the set-up and clear-down of data

calls, and monitors the connections and functions of the network. This exchange, which

is capable of handling 100 calls per second, may be supplemented at a later date with a

Special Service Centre (SSC) for the introduction of certain new facilities. The DSE is

connected to a Data Circuit Concentrator (DCC). The purpose of the concentrator is to

collect traffic from a number of individual subscriber circuits. This traffic is passed via

Time Division Multiplexed high-speed links (TDM) to the exchange. These TDMs,

which consist of time division multiplexed streams (64Kbps), also transfer traffic

between the DCC and one of the multiplexors (RMX). The multiplexors (RMX and

DMX) connect several suscriber lines either directly to the DSE or to the DCC which

passes traffic to the DSE. Between the RMX and the DMX and the Data Terminal

Equipment (DTE), the Data Circuit Terminating Equipment (DCE) is located in the

subscribers’ premises. It primarily provides the standardized interface between the DTE

and the network. Lastly, the DTE, which consists of a printer or alphanumeric visual

display terminal or a computer, provides the subscriber with data reception facilities.

DTE

Figure 1. The Nordic Public Data Network

DSE TDM D C C

R M X

TDM DCE

SSC DCE D M X

Page 14: Telecoms Book 07

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Vocabulary

clear-down (n) sù gi¶i phãng, sù xo¸ bá

concentrator (n) bé tËp trung

interconnect (v) nèi víi nhau

monitor (v) gi¸m s¸t

primarily (adv) chñ yÕu, ban ®Çu

route (n/v) ®Þnh tuyÕn

special service center (np) trung t©m dÞch vô ®Æc biÖt

stream (n) dßng, luång

supplement (v) bæ sung

synchronous (a) ®ång bé, theo c¸c h­íng

time division multiplexed high

speed link (np)

®­êng truyÒn tèc ®é cao ghÐp kªnh

ph©n chia thêi gian

Task 1. Match the components with their appropriate functions. Some components have

more than one function.

Components Functions

1 DCC a. introduction of new facilities

2 RMX/DMX b. provision of data reception facilities

3 DSE c. collection of traffic from subscriber circuits

4 DCE d. connection of subscriber lines

5 SSC e. transfer of traffic

6 TDM f. control of set-up and clear-down

7 DTE g. provision of interface between DTE and network

8 NPDN h. monitoring of network connections and functions

i. provision of a means of synchronous data

transmission.

Task 2: Answer the following questions about the text.

1. What is the basic purpose of NPDN?

.............................................................................………......................................................

2. What is the capability of the DSE?

.........................................................................................………..........................................

3. What does the NPDN consist of?

.....................................................................................................………..............................

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4. Where is the DCE located?

.................................................................................................................………………......

5. What does the DTE consist of?

........................................................................................................................……………...

Task 3: Decide if the following statements are True(T) or False(F).

1. Public Data Networks (PDN) can avoid the limitations of speed of transmission

over the switched public telephone because they are designed to monitor the set-up

and clear-down of data calls.

2. PDN consists of some components such as DSE, DCC, DCE… which are

interconnected.

3. The TDM high-speed links can transfer traffic between a concentrator and

multiplexors.

4. The DCE is located in the subscriber’s place.

5. The traffic is passed to the DSE from the DCC.

Task 4. Below are some of the facilities a subscriber in the Nordic Public Data Network

can have. Match them with the appropriate descriptions.

Facilities Description

1. Abbreviated address call

a. On dialling, the subscriber is always connected to

a pre-determined number

2. Direct call b. The same number is used for several equivalent

terminals. The connection is made to a free terminal

3. Closed user group c. A number of subscribers are protected against

calls from subscribers outside the group

4. Outgoing calls barred d. The subscriber cannot call other subscribers

5. Group number e. The subscriber uses only 2-digit numbers for a

limited number of other subscribers.

6. Connect when free f. The subscriber is informed of the cost of a call on

completion of a call.

7. Charge advice g. A call to an engaged connection is put in a queue

and established when it becomes free.

Answer: 1- 2- 3- 4- 5- 6- 7-

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Task 5. Translate the first paragraph starting 'Public Data Networks ...’ into Vietnamese.

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

........………………………………………………………………………………………

……………………………………………………………..…………………………….....

Task 6. Translate the following sentences into English.

1. Tæng ®µi chuyÓn m¹ch d÷ liÖu ®­îc kÕt nèi víi mét bé tËp trung chuyÓn m¹ch d÷ liÖu.

……………………………………………………………..…………………………….....

2. ThiÕt bÞ d÷ liÖu ®Çu cuèi lµ mét thiÕt bÞ bao gåm mét m¸y in hay bé thiÕt bÞ ®Çu cuèi

hiÓn thÞ ch÷- sè hay mét m¸y tÝnh.

……………………………………………………………..…………………………….....

3. Gäi trùc tiÕp cã thÓ ®­îc m« t¶ lµ khi quay sè, thuª bao th­êng ®­îc kÕt nèi víi mét sè

®iÖn tho¹i ®· ®­îc x¸c ®Þnh tr­íc

................................................................................................................................................

...........................................................

4. Khi ®· bÞ khãa cuéc gäi th× thuª bao kh«ng thÓ gäi cho c¸c thuª bao kh¸c ®­îc.

................................................................................................................................................

5. Chøc n¨ng cña ®­êng truyÒn ghÐp kªnh ph©n chia thêi gian lµ chuyÓn tiÕp l­u l­îng

®iÖn tho¹i gi÷a bé tËp trung m¹ch sè liÖu vµ mét trong c¸c bé ghÐp kªnh.

................................................................................................................................................

...............................................................................................................................................

Part II. Language in Use

Presentation 1. relative clauses

Study these sentences.

A. The sampling rate is determined by using Shannon’s Theory which states that the

sampling frequency must be double the maximum frequency of the signal.

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B. Many large companies, or groups working on the same site, are being faced with the

choice of continuing with their own PABXs, which may be electromechanical or

electronic, or of installing a LAN.

The clauses in bold modify the noun or noun phrase preceeding them in the main

clauses. In sentence A, the sub-clause modifies Shannon’s Theory while in sentence B,

the sub-clause modifies PABXs. Thus, they are called Relative Clauses or Adjective

Clauses. In ESP documents, Relative Clauses are widely used as they help make the

sentences more conscise and the content more comprehensible.

In Relative Clauses, the relative pronouns are who, which and that. Who is used for

people and which for things. That can be used for both people and things. These

pronouns can function as subjects or objects in the clauses.

E.g. This was confirmed by Shannon who/ that developed a theory which states a

Subj. formula for finding the correct sampling frequency.

The digital camera which/ that I bought the other day is a Sony Cyber-Shot.

Obj.

In case who, which and that are used as the object of a preposition, the preposition

can preceed who and which, or end the sub clause. However, the former way is more

preferable in ESP.

E.g. The principles of these two types of switching are illustrated in the following

figures in which we follow the speech paths of two subscribers through a small exchange

= The principles of these two types of switching are illustrated in the following

figures which we follow the speech paths of two subscribers through a small exchange in

Other pronouns, such as whose (for possession), when (for time), where (for place)

are also used in Relative Clauses, but not commonly in ESP.

Relative Clauses are usually of two kinds; Defining and Non-defining Clauses.

Defining Relative Clauses

Defining clauses give important information which denotes exactly what is being referred

to. In many cases, the main clause does not make full sense without the sub clause.

E.g. The conventional electronical communications services are based on the telephone

and the telegraph systems which independently run through the utilization of the

subscriber telephone network and telegraph relay switching network.

In the early 1970s Britain launched its Prestel system which is now offered as a

regular service by British Telecom.

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Non-defining Relative Clauses

Non-defining relative clauses add extra information. They are separated by commas in

writing and by a pause in speaking. We could miss out the relative clause and the

meaning would still be clear.

E.g. Northern Telecom Ltd. and Mitel Corp., which are two Canadian manufacturers,

captured 28% of the 2.8 billion- dollar market in BPX systems sold in the US in 1983.

N.B. - That cannot be used to introduce a non-defining clause.

- A relative clause introduced by which may modify the idea of the whole preceding clause.

E.g. Optical fibres are smaller, lighter and easier to install than coaxial cables, which is perfect for an office environment.

In this sentence the word which refers to the whole preceeding clause, “Optical fibres are smaller, lighter and easier to install than coaxial cables”.

PRACTICE

Ex.1. Underline Relative Clauses in the following sentences and state whether they are

defining (D) or non- defining (Non-D) clauses.

1. The growing need for data communication is reflected in the number of modems

installed, which has recently increased at a rate of 30% per annum.

2. The concept of the “wired city” in which any one can instantly talk to almost anyone

else by using the telephone or some other form of electronic device has become a reality

in countries such as these.

3. A technician who wants to move up to Junior Engineer will have to attend in-house

training at one of the 13 Telecoms Training Centers.

4. Each industrial location is connected to the station via high-speed data switches which

also provide facilities for interconnecting other regions and other multi-service networks.

5. Business users, who often have their own powerful data processing resources,

frequently require more sophisticated services which cover a variety of uses.

Ex.2. Now join these pairs of sentences, using Relative Pronouns.

1. a. The switching matrix consists of a number of connection points.

b. The connection points are made up of a horizontal and a vertical wire joined by a

relay.

.....................................................................................………..............................................

..........................................................................................……….........................................

2. a. Two types of switching equipment predominate in Sweden.

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b. These two types are crossbar equipment and digital system.

.......................................................................………............................................................

............................................................................................................……….......................

3. a. This technique appears to be very attractive.

b. A lot of money has been invested in this technique.

.........................................................................................................………..........................

............................................................................................................……….......................

4. a. The first rotary switch was invented by Almon Strowger.

b. This switch is still in use today.

c. Strowger was an undertaker in Kansas City.

.....................................................................………..............................................................

................................................................................................................………...................

5. a. The analogue signals are transmitted to the exchange.

b. The analogue signals are in the 300-3400 Hz range.

c. And these signals are sampled using PAM.

.........................................................................................................………..........................

.........................................................................................................………..........................

Presentation 2. expressing contrasting ideas

Study these sentences.

A. In the century since the birth of the telephone, the world telecommunications network

has evolved both in size, slowly at first and then with astonishing speed, and in the

techniques used to transmit information. The development has, however, been very

uneven for, by 1983, three quarters of the total number of telephone sets had been

installed in just nine countries.

B. In contrast to LAN suppliers, the effort of PABX suppliers has been placed, for the

main part, on replacing electromechanical systems with modern, electronic PABXs

where the customer’s requirements have been almost exclusive for voice-only systems.

It can be easily noticed in sentences A and B with words/ phrases in bold that there is

a sharp difference between the two clauses in one sentence, or between the two

successive sentences. In detail, sentence A points out that the development of the world

telecommunications network is uneven, though such development is fast (from the

previous sentence). Sentence B distinguishes LAN suppliers from PABX suppliers.

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Various words/ phrases can be used to contrast ideas, differentiate states. Below are

the most common ones. Notice the use of commas in the sentences.

But

But is a conjunction which contrasts in one sentence.

E.g. At the beginning of 1982 the USSR was estimated to have had 25 million telephone

sets, but East Germany, Poland and Czechoslovakia had just over 3 million each.

However, nevertheless, in contrast, on the other hand

However is a conjunction which is used to express contrast in formal speech or writing.

It is most commonly used at the beginning of a sentence but it can also come in the

middle or at the end.

E.g. - However, these PAM pulses are not transmitted directly over lines since they

would become distorted.

= These PAM pulses , however, are not transmitted directly over lines since they

would become distorted.

= These PAM pulses are not transmitted directly over lines since they would

become distorted, however.

In contrast, on the other hand are most commonly used at the beginning or in the

middle of a sentence.

E.g. - Prestel’s data banks are owned by British Telecom. In contrast, Teletel is open

to independent companies.

- Teletel provides electronic mail facilities. Prestel, on the other hand, has been

slow in offering this service to the general public.

While/ whereas

While and whereas are used in formal speech and writing. They compare two facts and

emphasize the difference between them.

E.g. Two Canadian manufacturers, Northern Telecom Ltd and Mittel corp., will capture

28% of the 2.8 billion dollar market in PBX systems sold in the US in 1983 while

Japanese and European countries will grab an additional 22%.

PRACTICE

Use these words: different, unlike, in contrast, however, on the other hand, but,

while, whereas to complete the following sentences.

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1. Videotext has an interactive capability. _________, Teletext simply provides

information

2. Teletext is _________ from Telex in that it is faster and offers more services.

3. Light-emitting diodes (LEDs) give less powerful signals but are much cheaper and

last longer. Lasers, ________ , produce light of a closely-defined wavelength and

suitable for monomode fibres.

4. Telidon offers more sophisticated graphics. Prestel, ________, has the advantage of

several years’ operating experience.

5. British Telecom, ________ many other associations, has discontinued its telegram

service.

6. Many developed countries are now introducing electronic telex switching networks.

________, some less developed countries have no telex networks at all.

7. Investment priorities in the Third World are focused on telephone sets _______ priorities in the industrialized world are concentrated on all the telecommunication services.

8. For links with Japan, telephone and text transmissions are essential. ______ , the facsimile transmission of plans, diagrams and Japanese character is equally important.

9. In 1982, there were almost 2,400,000 telephones in India _____ the population by then was over 700 million.

10. _______ most Videotex services can use the existing analogue network, business users frequently require more sophisticated services which cover a variety of uses.

Unit three

Public Communications Network

Part I. Reading comprehension

Read the passage do the following tasks.

The communications network can be roughly defined as an information transferring

system. Currently available electronical communications networks for processing various

types of information include a telephone network, telegraph network, and data

communications network. In addition, the Integrated Services Digital Network (ISDN) is

a network capable of processing the above integratedly. In the perspective of call types or

services, the communications networks can be classified into a public communications

network, dedicated communications network and mobile communications network. Also,

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based on the range of communications services offered, the communications networks

can be further classified into an intra communications network, local communications

network, toll communications network, and international communications network. The

instant communications network and dash communications network are available if we

classify them in terms of switching processing. As in the above, the communications

networks can be classified further according to the needs and requirements of the users.

Basically, the communications network consists of a switching system for designating

call connection paths according to the subscribers’ requests and a transmission system for

transferring call information to the destinations. It should basically meet the following

conditions:

1) It should be capable of connecting calls made by the originating subscribers registered

in the system to all the terminating subscribers at any time or pre-set times.

2) It should be capable of meeting the transmission requirements and characteristics.

3) The numbers for designating terminating subscribers should be standardized.

4) It should be capable of carrying out accurate and highly reliable communications.

5) It should have a rational billing system.

6) Its operation should be economical and flexible.

To realize the above, the switching system network should be designed and then, set up

adequately by considering call quality, call processing capacity, and installation and

operation cost, and the relationship between the transmission system and switching

system. The above mentioned items can be summarized as call connection and

transmission criterial, numbering plan, reliability and billing system.

Vocabulary

define (v) ®Þnh nghÜa

integratedly (adv) tæ hîp, tÝch hîp

ISDN m¹ng sè ®a dÞch vô

register (v) ®¨ng ký

reliability (n) ®é tin cËy

requirement (n) yªu cÇu

standardized (a) ®­îc chuÈn ho¸

terminating subscriber (np) thuª bao bÞ gäi

transmission criterial (np) tiªu chÝ truyÒn dÉn

Task 1: Answer the following questions.

1. According to the text, what is the ISDN ?

..............................................................................……….....................................................

……………………………………………………………………………………………

2. How many ways are used to classify networks from a communication network?

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...............................................................................………....................................................

3. What should the operation of the communications network be like?

............................................................…………...................................................................

4. What should be considered when switching system networks are designed and set up?

................................................................................………...................................................

Task 2: What do these words in italics in these sentences mean ?

1. The communications network can be roughly defined as an information .........

a. definitely b. totally c. approximately

2. ............ the communications networks can be classified into.............

a. divided b. laid out c. presented

3. Basically, the communications network consists of .................

a. makes up of b. includes c. covers

4. ............. set up adequately by considering call quality................

a. correctly b. exactly c. fully

5. The above mentioned items can be summarized .................

a. referred to b. talked about c. considered

Task 3: Fill in the blanks with suitable missing words.

The switching system network should be ____________ and then, set up adequately by

considering call quality, call processing capacity, and ____________ and operation cost,

and the relationship between the ___________ system and switching system. The above

mentioned items can be _____________ as call connection and transmission criterial,

numbering plan, reliability and ____________ system.

Task 4: Translate the paragraph starting “The telecommunications networks ...........

destination” into Vietnamese.

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

.......................

Task 5: Translate these sentences into English

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1. NÕu cÇn thiÕt th× mét m¹ng néi h¹t mµ bao gåm mét hoÆc hai hÖ thèng chuyÓn m¹ch cã

thÓ ®­îc thiÕt lËp.

...................................................................................................................................

2. §Ó ®¸p øng nhu cÇu ngµy cµng t¨ng cña viÖc truyÒn sè liÖu vµ c¸c dÞch vô ®iÖn tho¹i

míi, ng­êi ta ®· ph¸t triÓn vµ thùc hiÖn c¸c dÞch vô chuyÓn m¹ch sè liÖu kü thuËt sè.

...............................................................................................................................................

.......................................................................................................................

3. M¹ng d÷ liÖu chuyÓn m¹ch ®­îc sö dông ®Ó nèi c¸c ®­êng d©y th«ng tin tõ c¸c bªn gäi

®Õn c¸c bªn nhËn vµ sau ®ã thùc hiÖn viÖc trao ®æi th«ng tin gi÷a c¸c bªn víi nhau.

...............................................................................................................................................

...............................................................................................................................................

..................................................................................................

Part II. Language in Use

Presentation 1. gerunds (V-ing form)

Study this sentence.

To realize the above, the switching system network should be designed and then, set up adequately by considering call quality, call processing capacity, and installation and operation cost, and the relationship between the transmission system and switching system.

All the words in bold are called Gerund for they are verbs but behave like nouns. They are formed by adding -ing to the verb base. They can function in four cases as follows.

As the subject of a clause or a sentence

E.g. Radio-paging would be very useful within the plant, and from the warehouse to distribution vehicles.

As the object of a clause or a sentence

E.g. French telecoms researchers began exploring the subject of electronic switchingin mid- 1960s.

After certain verbs

* After verbs expressing likes and dislikes such as: like, love, enjoy, fancy, dislike, hate, detest...

* After other verbs such as: admit, avoid, deny, finish, forgive , give up, keep, put off, suggest...

After prepositions

* After most prepositions in reduced clauses

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E.g. After leaving the discriminator, the separated audio and video signals are sent to another unit called the Radio Frequency Modulator.

* After adjective + preposition combinations such as:

nervous/ worried about expert /interested in

bad/good/clever/skilled at capable/afraid/frightened/terrified of

sorry/responsible for bored with

E.g. She was interested in applying for the job as a telephone operator.

* After verb + preposition combinations such as: apologize for, get used to, consist of, insist on, look forward to, succeed in ...

PRACTICE

Put the verbs in brackets into the correct form and translate the sentences.

1. Instead of (travel) ………………….to meetings, executives can speak to and watch one another on a TV link without (leave) …………………their office.

2. Further copies can be made by (reprint) ……………… the message from the memory in the local mode.

3. Swedish Space Coperation (SSC) is responsible for (maintain) …………………… links with industry.

4. The International Programme for Telecommunications Management also deal with (plan) …………………………and (programme) ………………….. for future network growth.

5. The (launch) ………………… of the first satellite by the Russians in 1957 began the “space race”.

6. A satellite represents a relatively cheap way of (transmit)……………………. information over long distances.

7. (Link) ………………….. up the customers through a series of computer systems to US-based airline computers may seem technically advanced.

8. One link can be used for (signal) ………………… many simultaneous transactions and hence is called a “common channel”.

9. French domestic satellite systems would also be capable of (handle) ……………….…. high speed facsimile as well as (contain) ……………………… a number of telephone channels.

10. After a period of theoretical instruction in E10 design, engineering, administration and maintenaice, the Indian engineers will be assisted by French experts in (apply)………………………..their knowledge to their everyday work.

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Presentation 2. expressing concession

Relationships between ideas, usually expressed in clauses or phrases, can vary from cause and effect, purposes, time relationship, etc. to concession or opposition. Below are some common conjunctions and phrases that begin a sub clause or a phrase to express unexpected results in two-clause sentences.

Notice the position of these sub clauses and the comma used to separate them from the main clauses.

Although/ though

E.g. Although Chief Executive Barry Douglas has not been in charge for long, there has already been a dramatic upturn.

There has already been a dramatic upturn although Chief Executive Barry Douglas has not been in charge for long.

Even though is a conjunction which is often used in informal speech instead of although. It puts greater emphasis on the concession between the ideas .

Despite/ in spite of

* Despite + Noun or Gerund

E.g. Despite/ In spite of remarkable losses, the director still managed to reduce production cost.

* Despite the fact (that) + clause

E.g. Despite/ In spite of the fact that Chief Executive Barry Douglas has not been in charge for long, there has already been a dramatic upturn.

N.B. It is only correct to use despite + V-ing when the subject of the V–ing form is the same as the subject of the verb in the main clause.

E.g. Despite speaking more slowly, I still couldn’t understand him. (wrong)

Despite speaking more slowly, he still couldn’t make me understand him.

(correct)

PRACTICE

Ex.1. Rewrite these sentences using the words in the brackets.

1. Despite her using the telephone, she still doesn’t know that her speech is broken up into small batches of time. (although)

........................................................................................................................………...........

...............................................................................................................………....................

2. Mary got the job as a telephonist even though she didn’t expect to. (in spite of)

..........................................................................................................................……….........

3. In spite of not knowing her full name, he managed to search for her telephone number in the telephone directory. (although)

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...........................................................................…………....................................................

................................................................................................................................………...

4. Although most developing countries attach a high priority to telephone networks, they lack money to buy large numbers of multi-million dollar switches. (in spite of)

...............................................................................................................………....................

...............................................................................................................................................

5. Although there is a development towards ISDN, a number of specialized networks will have to live side by side for many years to come. (despite)

..........................................................................................................................……………

..........................................................................................................................…………….

Unit four

Electronic Exchanges

Part I. Reading comprehension

Read the passage and do the following tasks.

Most of the world’s telephone traffic is still handled by exchanges of electromechanical

design, each with thousands of wear-prone exposed moving parts. Analogue exchanges

of this type are costly to install and maintain, and are subject to familiar faults such as

crossed lines, noise and wrong numbers.

Many of the world’s telecommunications administrations have explored other digital

solutions. They are designing networks that offer a much higher quality of service than

before, using the latest microchip technology with few or no moving parts; less

interference than previously; lower installation and maintenance costs; and much faster

connection speed for calls and fewer wrong numbers than in the past.

The main characteristics of a digital exchange are:

1. Integrated Digital Transmission and Switching.

Speech and other signals are digitally encoded and a common method of time division

multiplexing is used in both transmission and switching equipment. The main advantage

of this system is that the transmission loss encountered by speech becomes more or less

independent of both distance and the number of exchanges through which a call is routed.

2. Stored Program Control (SPC) is the application of data processing and computer

techniques to an exchange, thus providing a powerful, flexible method of controlling the

operation of the exchange.

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3. Common Channel Signalling (CCS) uses just one (go and return) pair of signalling

channels, not directly associated with the traffic circuits, for performing all the signalling

functions of an entire route which may contain several hundred traffic circuits.

4. Microelectronics technology is the application of solid-state semi-conductor

technology to provide components which range in function from a single active element

(e.g. a transistor) to large scale integrated circuits. Use of this technology offers small

physical size and reliability together with automated design, manufacture and testing. The

components are fixed onto printed circuit boards, and if there is a fault, the defective

printed circuit board can be taken out and replaced by another in a matter of seconds.

Vocabulary

associated (a) kÕt hîp

circuit board (nph ) b¶ng m¹ch ®iÖn

decode (v) gi¶i m·

defective (a) bÞ lçi, cã lçi

encode (v) m· ho¸

fix (v) g¾n, cµi ®Æt

integrated (adj) tæ hîp, tÝch hîp

single active element (np) phÇn tö kÝch ho¹t ®¬n

transistor (n) m¸y b¸n dÉn

wear-prone (n) dÔ háng, dÔ mßn

Task 1. Fill in the blanks below to compare the difference between eletromechanical

exchange and digital exchange.

Classification Electromechanical exchange Digital exchange

Transmission

type

analogue transmission digital transmission and

switching

Installation a…………………………… a. lower installation cost

Maintenance b. high maintenance cost

c.............………….……......

b…………………………….

c. reliability and easy replacement

Technical

comments

d. crossed lines

e..........………………..........

f. rigidity of design

g. wrong numbers

h.........………….…..............

d........………………............

e. less interference than prevously

f.............…………….….......

g...........……………….........

h. much higher connection speed

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Task 2. Match each of the headings (1-4) with one set of functions (a-d).

1. Stored Program

Control

2. Common Channel

Signalling

3. Integrated Digital

Transmission and

Switching

4. Microelectronics

Technology

a. The application of solid-state semi- conductors to

provide greater reliability, smaller size and automated

design.

b. The application of data-programming techniques to an

exchange, providing greater control and flexibility in

the operation of an exchange

c. The use of one pair of channels not directly associated

with the traffic circuits, to perform all signalling

functions on a complete route.

d. Speech and other signals are digitally encoded and a

common method of time-division multiplexing is

used.

Answer: 1- 2- 3- 4-

Task 3. Answer the following questions about the passage.

1. What exchanges have thousands of wear-prone exposed moving parts?

................................................................................................................………...................

2. What are the disadvantages of analogue exchanges?

............................................................................................................................……….......

3. What kind of networks are many of the world’s telecommunications administrations

designing?

.................................................................................................................................………..

4. How many main characteristics does a digital exchange have?

.................................................................................................................................………..

5. What does CCS stand for?

.................................................................................................................................………..

Task 4. Decide if the following statements are True (T) or False (F) or No Information

(NI).

1. An electromechanical exchange is a switching centre and the design of which is

based on thousands of moving parts.

2. A digital exchange is an exchange which uses a pair of signalling channels.

3. Analogue transmission is a system in which a varying electrical current transmits

the caller’s voice pattern.

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4. A call which is correctly routed is a wrong number.

5. During a telephone conversation, you hear another conversation at the same time,

and this is called a crossed line.

Task 5. Translate into Vietnamese the paragraphs from ‘The main charateristics of a

digital exchange are ...........’ to the end of the passage.

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

Task 6. Translate the following sentences into English.

1. ViÖc sö dông c«ng nghÖ vi m¹ch ®iÖn tö cho ta kÝch th­íc vËt lý nhá vµ ®é tin cËy

cïngvíi viÖc thiÕt kÕ s¶n xuÊt vµ thö nghiÖm ®­îc tù ®éng ho¸.

...............................................................................................................................................

...................................................................................................................... .

2. C«ng nghÖ vi m¹ch lµ mét trong nh÷ng ph¸t minh lín cña nh©n lo¹i trong lÜnh vùc

®iÖn tö ë thÕ kû 20.

...............................................................................................................................................

...........

3. Trong hÖ thèng KiÓm so¸t Ch­¬ng tr×nh L­u tr÷ (SPC), phÇn chuyÓn m¹ch bao gåm

c¸c d©y dÉn vµ c¸c mèi tiÕp xóc.

...............................................................................................................................................

...........

4. PhÇn nµy còng chøa c¸c m¹ch ®Ó thùc hiÖn c¸c chøc n¨ng ®iÖn tho¹i ®¬n gi¶n.

...............................................................................................................................................

5. Kü thuËt c¬ ®iÖn ®­îc ¸p dông cho chuyÓn m¹ch, cßn kü thuËt ®iÖn tö ®­îc dïng cho

phÇn ®iÒu khiÓn cña hÖ thèng nµy.

……………………………………………………………..…………………………….....

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Part II. Language in Use

Presentation 1. comparisons of adjectives

1. Equality level

as + adj + as

not as/so + adj + as

E.g. The crossbars were not as noisy as Strowger. The number of telephones in the UK is as large as in France.

2. Comparative level

Comparatives show how two things are different. The form of the comparatives depends on how many syllables the adjective has.

Type of Adjectives Examples Rules

Adjectives with one syllable

(short adjectives)

The number of channels is greater than the number of repeaters. short adj + er + than

Adjectives with two or more syllables

(long adjectives)

The new type of exchange is more convenient than the old one.

more + long adj + than

less + ……..

Adjectives ending in - y This mobile phone is easier to use than that one.

adj-y→ i + er + than

Irregular adjectives Our digital switching centre is better than theirs.

The door-to-door service for customers at Stella Co. now is worse than (the service) before.

good → better adj → worse far → father/further little → less much/many → more few → fewer

3. Superlative level

Superlatives are used to compare three or more people or things. The form of superlatives depends on how many syllables the adjective has.

Type of Adjectives Example Rule

Adjectives with one-syllable

(short adjectives)

That chip carries the smallest electrical circuit. the + short adj + est

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English for Telecoms Industry. English Section. 2007. 32

Adjectives with two or more than two syllables

(long adjectives)

Maximo is the most intelligent robot in our lab.

the most + long adj

the least + ……..

Adjectives ending in - y D 00208 is the noisiest motor that we are having.

the + adj-y→i + est

Irregular adjectives The best digital switching centres have a lot of advantages.

The present after-sale service for customers in their company is the worst so far.

good → the best bad → the worst far → the farthest/ the furthest little → the least much/many → the most

PRACTICE

Ex.1. Fill in the blanks with the appropriate forms of the adjectives in the brackets.

1. In my opinion, Bell is …………..…… inventor of all time. (great)

2. A Strowger exchange is………………. crossbar central office. (noisy)

3. A Stronger exchange is not …………………….crossbar. (reliable)

4. Viettel does not have ……………….subscribers …….VinaPhone. (many)

5. Bell made a lot of inventions, but telephone was………………... (important)

6. Before inventing the automatic exchange, Strowger found that his business became ………………… (profitable)

7. A digital exchange is……………..a crossbar one. (fast)

Ex.2. Translate the following sentences into English.

1. Điện thoại là phát minh quan trọng nhất của ông Bell.

…………………………………………………………………………………………......

2. Lắp đặt một tổng đài cơ điện tử thì đắt hơn lắp đặt một tổng đài kỹ thuật số.

……………………………………………………………………………………………...……………………………………………………………………………………………...

3. Tốc độ kết nối của tổng đài cơ điện tử không cao bằng tốc độ kết nối của tổng đài kỹ thuật số.

…………………………………………………………………………………………………………………………………………………………………………………………

Presentation 2. PRESENT PERFECT vs PAST SIMPLE

Study these sentences.

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English for Telecoms Industry. English Section. 2007. 33

A. Strowger's automatic exchanges underwent several modifications.

B. The principle has remained the same ever since.

In sentence A, the action took place in the past and is now finished. In sentence B, ‘ever

since’ links the past to the present. Hence, the verb in A is formed in the Past Simple

while the verb in B is in the Present Perfect.

The Present Perfect always connects the past to the present whereas the Past Simple tells us only about the past. Let’s compare:

We use the Present Perfect We use the Past Simple

a. to talk about something which started in the past and continues up to the present.

These electromechanical exchanges have been in use for 5 years.

(They are still in use now)

to talk about something which started and finished in the past.

These electromechanical exchanges were in use for 5 years.

(They are not in use now)

b. when the result of a past action is connected to the present.

The man has lost his mobile phone.

(He hasn’t got it now)

when the result of a past action is not connected to the present.

The man lost his mobile phone, but he has found it now.

c. to talk about an indefinite time up to the present.

They have never used this service before.

when we say about a definite past time.

They used this service 2 years ago.

PRACTICE

Ex.1. Put the verbs in brackets into the correct tenses. In some cases, both the Present Perfect and Past Simple are possible.

1. Bell…………..the first words on the phone in 1875. (speak)

2. Over the last few years, electromechanical exchanges …………to disappear. (begin)

3. It …………..necessary to find a way to link up subscribers. (become)

4. Computers ……………….commercially for the first time in the 1950s. (be sold)

5. In the early exchanges, all calls …………….through the operator. (go)

6. Bell ………. to experiment with ways in which people could communicate over long distances. (begin)

7. With digital techniques, telephone exchanges…….another great change. (undergo)

8. Strowger …….for his idea in 1889. (patent)

9. Not long ago it ……..possible to make telephone calls across the Atlantic Ocean.

(become)

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English for Telecoms Industry. English Section. 2007. 34

10.The operator always ………….calls for Strowger to other undertakers. (connect)

Ex.2. Use the words given to build up complete sentences.

1. There / be / great / increase / number / subscribers / during / last ten years /.

……………………………………………………………………………….......................

2. Teletel computer center / Velizy / use / modular minicomputer system / handle / both / switching / database function /.

……………………………………………………………………………………………...

………………………………………………………………………...................................

3. Centre / be design / handle / 300 / simultaneous call / 2.500 subscribers /.

...............................................................................................................................................

4. Number / subscribers / be protected / calls / subscribers / outside / group /.

...............................................................................................................................................

5. Subscriber circuit / consist / telephone / set / customer’s premises / cable pair /.

..............................................................................................................................................

unit five

Transmission Systems

Part I. Reading Comprehension

Read the passage and do the following tasks.

Many different transmission systems are used in telecommunications technology.

Transmission on open-wire lines was the earliest method used for telephone traffic, and

this method is still used in the local networks of many countries. Nowadays, due to the

demands on operating reliability, local networks are built up using aerial or underground

cables.

Between the subscriber and the local exchange, two-wire circuits are used, often placed

in symmetric cable pairs. Between the local and transit exchanges either two or four-wire

circuits are used. On longer routes, it may be advantageous to use PCM on coaxial

cables. These cables are also used for FDM systems transmitting up to 10,800 telephone

channels. At regular intervals along the coaxial line, line amplifiers are provided; these

are mounted in underground housings and are called ‘intermediate repeaters’. In

principle, the greater the number of channels is transmitted, the larger the number of

repeaters is required.

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English for Telecoms Industry. English Section. 2007. 35

Since 1965, satellites have become increasingly important for long distance

communication, especially across the oceans. In principle, the satellite operates as an

intermediate repeater; signals are received, amplified and transmitted to the ground

station on the receive side. Satellites use the same frequency band as radio relay systems.

Radio relay links operate with line in sight between the send and receive stations. In

principle, the greater the diameter of the parabola in relation to the wavelength is, the

higher the degree of directivity becomes.

In terminal repeater stations, situated in ground stations and transit exchanges, speech

signals are modulated and combined before transmission. Each separate conversation is

shifted to a significantly higher frequency range. This is done in a number of steps. First,

by selecting suitable modulation frequencies, the conversations can be placed next to

each other along the frequency axis. Then, they are transmitted as a group to the receive

side where a similar station demodulates the signals and extracts the various

conversations before they are transmitted in two or four- wire circuits to another transit

exchange.

Vocabulary

aerial cable (n) c¸p treo

amplify (v) khuyÕch ®¹i

axis (n) trôc

demodulate (v) ®iÒu chÕ, ®iÒu tiÕt

diameter (n) ®­êng kÝnh

directivity (n) ®Þnh h­íng

extract (v) t¸ch ra

interval (n) kho¶ng c¸ch

open-wire line(np) ®­êng d©y trÇn

radio relay link (n) v« tuyÕn chuyÓn tiÕp

repeater (n) bé lÆp

significantly(adv) quan träng, ®¸ng kÓ, ®Çy Ên t­îng

wavelength (n) b­íc sãng

with line in sight (n) trong tÇm nh×n th¼ng

Task 1. Answer the following questions about the text.

1. Why are local networks built up using cables rather than open wire lines?

..................................................................................................……….................................

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English for Telecoms Industry. English Section. 2007. 36

2. What types of cables are used for FDM systems which transmit up to 10,800

telephone channels?

..............................................................................................................……….....................

3. What is another term for ‘intermediate repeaters’?

..........................................................................................................................……….........

4. What are the three functions of a satellite?

..................................................................................................................................……….

Task 2. Choose the best answer to fill in the blank in each sentence below.

1. Transmission on open-wire lines ...........................

A. was the earliest method used for telephone traffic.

B. is used in technology industry.

C. is not used in the local networks of many countries.

D. use aerial or underground cable.

2. Two-wire circuits are used ............................

A. between the subscriber and transit exchanges

B. between the subscriber and the local exchanges

C. in symmetric cable pairs

D. between the local exchanges

3. It is suggested that PCM is used ......................

A. to transmit up to 10,800 telephone channels

B. for FDM systems

C. on longer routes on coaxial cable

D. because it is good

4. ‘Intermediate repeaters’ are the other names of .....................

A. underground housing

B. regular intervals

C. satellites

D. line amplifiers

5. When the diameter of the parabola in relation to the wavelength is greater, ..................

A. the radio relay has higher degree

B. it is easier for directivity

C. the degree is higher

D. the degree of directivity is lower

Task 3. Decide if the following statements are True, False or No Information.

1. Transmission systems are used differently in telecommunications technology in many

countries.

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English for Telecoms Industry. English Section. 2007. 37

2. Aerial or underground cable is used in the local networks to avoid danger.

3. Coaxial cables are capable of transmitting FDM (Frequency Division Multiplex)

systems to telephone channels.

4. Satellites started to become important for long distance communication in 1965.

5. The terminal repeater stations are situated in ground stations.

Task 4. Translate the first two paragraphs into Vietnamese.

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

.....................................................................................................................................

Task 5. Translate the following sentences into English.

1. C¸c linh kiÖn ®iÖn tö ®­îc s¶n xuÊt t¹i NhËt b¶n vµ chuyÓn tíi c¶ng Leyport. Tõ ®ã,

chóng ®­îc ®­a th¼ng tíi nhµ m¸y l¾p r¸p ®Æt t¹i vïng ngo¹i « cña thµnh phè.

...............................................................................................................................................

...............................................................................................................................................

2. Trong nh÷ng n¨m gÇn ®©y, nh÷ng tiÕn bé v­ît bËc trong lÜnh vùc viÔn th«ng ®· më

®­êng cho viÖc giíi thiÖu nh÷ng lo¹i h×nh dÞch vô míi vµ ®­îc c¶i tiÕn.

...............................................................................................................................................

.......................................................................................................................

3. Nhê cã c¸c vÖ tinh viÔn th«ng mµ c¸c buæi truyÒn h×nh giao l­u trùc tiÕp gi÷a c¸c ®Þa

ph­¬ng kh¸c nhau cã thÓ thùc hiÖn ®­îc.

...............................................................................................................................................

.......................................................................................................................

4. ë nh÷ng n­íc ®ang ph¸t triÓn nh­ ViÖt Nam, hÖ truyÒn dÉn l­u l­îng ®iÖn tho¹i b»ng

d©y trÇn vÉn cßn rÊt phæ biÕn.

...............................................................................................................................................

......................................................................................................................

5. Bé lÆp trung gian ®­îc l¾p ®Æt däc theo ®­êng c¸p ®ång trôc ®Ó khuyÕch ®¹i ®­êng d©y

nµy..........................................................................................................................................

............................................................................................................................

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English for Telecoms Industry. English Section. 2007. 38

Part II. Language in Use

Presentation 1. REDUCED adjectIVE CLAUSES

Study these sentences.

Transmission on open-wire lines was the earliest method used for telephone traffic.

= Transmission on open-wire lines was the earliest method (which is) used for telephone

traffic.

Between the subscriber and the local exchange, two-wire circuits are used, (which are)

often placed in symmetric cable pairs.

The adjective phrases in bold are initially Adjectives Clauses, which have been

reduced/ shortened to make the sentences more concise, more of scientific style.

Reduced Adjective Clauses are usually of two types as follows:

Active adjective clauses: The active adjective clause starting with who, which,

that can be replaced by a Present Participle (V+ ing) of the main verb in that

clause.

E.g. The subscribers who choose this service do not have to pay for the installation.

→ The subscribers choosing this service do not have to pay for the installation

Users are men or machines which receive information recovered from the

receiver.

→ Users are men or machines receiving information recovered from the receiver.

Passive adjective clauses: The passive adjective clause starting with who, which,

that can be replaced by a Past Participle (PII) of the main verb in that clause.

E.g. The customers who are served with this service are often pleased.

→ The customers served with this service are often pleased.

These services can be accessed through software which are installed outside the

geographical area of test.

→ These services can be accessed through software installed outside the

geographical area of test.

* Note: It is necessary to distinguish between the regular verbs in Simple Past Tense or in

reduced form.

E.g. In 1892, three years after patenting his ideas, Almon B. Strowger saw his system

installed at La Porte, Indiana. (reduced form)

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English for Telecoms Industry. English Section. 2007. 39

The university installed a LAN on the campus about 10 years ago.

(Simple Past)

PRACTICE

Ex.1. Underline the reduced adjective phrases in these sentences and state what type they

are of.

1. In terminal repeater stations, situated in ground stations and transit exchanges, speech

signals are modulated and combined before transmission.

2. These cables are also used for FDM systems transmitting up to 10,800 telephone

channels.

3. Teletex is an international service enabling subscribers to exchange correspondence on

an automatic memory-to-memory basis.

4. The main advantage of this system is that the transmission loss encountered by speech

becomes more or less independent of both distance and the number of exchanges through

which a call is routed.

5. The technique used in this exchange is known as space division switching.

Ex.2. Rewrite the following sentences, using a Present Participle or a Past Participle to

begin the adjective phrases.

1. Machine-run-information-announcement service is characterized by the machine

which acts as information source and by men who serve as users.

...............................................................................................................................................

...............................................................................................................................................

2. The communications which are carried out through the interface between men and

machines, and between machines are expected to become more popular.

...............................................................................................................................................

...............................................................................................................................................

3. The conventional electronically communications services are based on the telephone

and the telegraph systems which independently run through the utilization of the

subscriber telephone network and telegraph relay switching network.

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

4. Transmitter is a device or an equipment for converting information which is generated

into signals that are transferred via a transmission line.

...............................................................................................................................................

...............................................................................................................................................

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English for Telecoms Industry. English Section. 2007. 40

5. The main role of the center is to act as an interface for the user, enabling him or her to

get into contact with the exact service which is required.

...............................................................................................................................................

...............................................................................................................................................

6. The center has been designed to handle 300 simultaneous calls which are made from

the 2,500 subscribers.

...............................................................................................................................................

...............................................................................................................................................

Presentation 2. DOUBLE COMPARATIVES

Study these sentences.

In principle, the greater the diameter of the parabola in relation to the wavelength is, the

higher the degree of directivity becomes.

In principle, the greater the number of channels is transmitted, the larger the number of

repeaters is required.

The phrases in bold show the consequential relationship between the two clauses in a sentence, which is expressed in a form of comparison called ‘Double Comparative’.

Form:

[The + (comp.) Adj/Adv + S1 + V1, the + (com.) Adj/Adv + S1 + V2 clause 2] E.g.

The greater the number of channels is, the larger the number of repeaters becomes. The greater the diameter of parabola in relation to the wavelength is, the higher the degree of directivity gets.

Nu

mb

er o

f ch

ann

els

Number of repeater

Dia

met

er o

f pa

rabo

la

wav

elen

gth

Degree of directivity

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English for Telecoms Industry. English Section. 2007. 41

Note that when talking about ‘degree’ or ‘frequency’ we normally use ‘higher’ or ‘lower’ to modify it.

PRACTICE Make similar sentences for the following relationships.

a. .......................................................................

.......................................................................

.......................................................................

b. .......................................................................

.......................................................................

.......................................................................

c. ............................................................................

............................................................................

............................................................................

d. ...........................................................................

............................................................................

............................................................................

Fr

eq

ue

nc

y

Number of samples/sec (per second)

Deg

ree

of n

etw

ork

di

git

aliz

atio

n

Number of exchanges

Nu

mbe

r of

ch

ann

els

Cost of transmission

Deg

ree

of a

uto

mat

ion

Number of manual operators

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English for Telecoms Industry. English Section. 2007. 42

Unit six

Radio Communications

Part I. Reading comprehension

Read the passage and do the following tasks.

Communicating by radio is a method of sending or receiving sounds, pictures and data

through the air by means of electro-magnetic waves.

We use the airwaves for many purposes: broadcasting most of local and national radio

and TV stations, in our mobile radio and telephone services, and communicating on

global scale through distant satellites, which act as a kind of reflector in the sky,

redirecting the information we send up to them.

Another important use of this means of communicating is in shipping. A ship that is in

difficulty can call the nearest coast station, giving details of its situation and, if necessary,

ask for help. We call this ship-to-shore radio. Radio can ensure greater safety in

navigation (for example, to warn of bad weather or of hazards in shipping lanes) and it

enables large amounts of information to be sent over land or water without the support of

several hundred kilometers of wires and cables. Radio network can, therefore, be cheaper

to install but often have fewer circuits than cable links. Radar systems also enable air-

traffic controllers to follow and guide the flight paths of planes from take-off to landing.

Radio-paging systems enable us to be contacted even though we do not have a telephone

within easy reach. It is a way of letting us know that something important has just

happened and that we must act quickly. The system works through a pager or “bleeper”,

a small receiver about the size of a packet of cigarettes, which you can keep in your

pocket.

When people want to contact you, they simply pick up the nearest telephone, dial your

personal paging number free of charge, and wherever you are in the coverage area, your

pager will bleep. (You must, however, be above, not below ground level, for the signal

will not get through if you are underground.) The bleeping informs you that someone is

calling you. You can identify up to four callers on some types of equipment. The most

modern type of radio-pager displays the number of the telephone the caller is ringing

from. The main advantage of radio-paging is that you can be contacted wherever you are,

even though you may be a long way from a telephone set.

Vocabulary

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broadcast ( v) ph¸t thanh, ph¸t sãng

coverage area (np) vïng phñ sãng

navigation (n) hµng h¶i, sù ®i biÓn

pager (n) m¸y nh¾n tin

radio-paging (n) nh¾n tin v« tuyÕn

reflector (n) bé ph¶n x¹

ship-to-shore radio (np) liªn l¹c v« tuyÕn tµu bê

within easy reach trong tÇm tay

Task 1: Read the text and answer the following questions.

1. How does the text define radio communication?

.............................................................................................................………......................

2. What examples does the text give of radio communications?

...........................................................................................................………........................

...........................................................................................................………........................

3. Why can radio networks be cheaper to install?

.......................................................................................................………............................

4. What equipment does the radio-paging user need?

...........................................................................................................………........................

5. Where does the user keep this equipment?

.....................................................................................................................………..............

6. Where is it impossible for you to be contacted by radio?

......................................................................................……….............................................

Task 2: What do these words in italics in these sentences mean ?

1. We use the airwaves for many purposes.............

a. aims b. fields c. aspects

2. ........... which act as a kind of reflector in the sky..................

a. behave b. work c. play

3. .......... and it enables large amounts of information to be sent over land ....

a. makes way b. allows c. lets

4. When people want to contact you,..............

a. reach b. get in touch with c. keep

5. The bleeping informs you that someone is calling you.

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English for Telecoms Industry. English Section. 2007. 44

a. tells b. announces c. indicates

Task 3: Decide whether the statements are True (T) or False (F).

1. Air waves are only used in broadcasting local and national radio and T.V

stations.

2. In difficulty, a ship cannot contact the nearest coast station.

3. Radio network cannot be as expensive as cable links to install.

4. When you’re called, the bleeper will give signals.

5. Radio-paging is advantageous because you can be reached wherever you are.

Task 4: Translate the third paragraph starting from “Another important use.........

landing” into Vietnamese.

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................

Task 5: Translate the following sentences into English.

1. VÖ tinh tõ xa ®ãng vai trß nh­ mét bé ph¶n x¹ trªn bÇu trêi ®Ó ®Þnh h­íng l¹i nh÷ng

th«ng tin mµ nã nhËn ®­îc.

....................................................................................................................................

.......................................................................................................................................

2. HÖ thèng m¸y nh¾n tin v« tuyÕn vËn hµnh b»ng mét m¸y nh¾n tin, lµ mét m¸y thu cì

nhá mµ ng­êi sö dông cã thÓ bá tói.

.....................................................................................................................................

...............................................................................................................................................

3. Ngµy nay, m¸y nh¾n tin ®· bÞ ®iÖn tho¹i di ®éng thay thÕ hoµn toµn.

.....................................................................................................................................

4. Tuy vËy, vÉn cã nh÷ng ng­êi l­u gi÷ mét chÕc m¸y nh¾n tin nh­ lµ mét vËt kû niÖm

cho thêi kú ®Çu cña c«ng nghÖ truyÒn th«ng v« tuyÕn.

.....................................................................................................................................

.....................................................................................................................................

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English for Telecoms Industry. English Section. 2007. 45

Task 6: Complete the description of the following flow chart by putting the verb in

brackets into the correct form ( ____ ) and inserting an appropriate preposition (…… )

ship

truck

truck

The components ________(manufacture) in Japan and ________(ship) to Leyport docks.

From here, they ________( transport ) directly to our assembly plant……… Leyport.

Three models ________ (assemble) ……….. the plant: the 75cc, 125cc and 150 cc

motorcycles. When they_______(assemble), they _______(take) …….. truck …….. the

warehouse ……… the suburbs of Leyport . …….. here they _______ (distribute)

……….dealers throughout the country.

The technical support services department …….. London is available to assist the

assembly plant and to help dealers ……… service problems. The training section, which

_______(come) under the Personel, _______ (be) also available to train assembly

workers. The marketing department ________(liaise) ……… the dealer ………

promotion campaigns …….. public.

Component manufacture in Japan

Leyport Costerutsi

Assembly in Leyport

Warehouse in Leyport

Dealers

Customers

Training

Technical support services

Marketing

Technical support services

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English for Telecoms Industry. English Section. 2007. 46

Part II. Language in Use

Presentation 1. PAST PARTICIPLE

Study these sentences.

A. The main advantage of radio-paging is that you can be contacted wherever you are.

B. It is a way of letting us know that something important has just happened.

C. Owing to radio transmission, we can have large amounts of information sent over land or water to us.

The verbs in bold are in Past Participle form. In sentences A and B, the verbs are part of the main clauses, while in sentence C, the verb is part of the adjective phrase.

Let’s consider the Past Participle from two aspects as follows:

Form

All English verbs, except the modal ones, have the Past Participle form (PII). They are grouped into two types in terms of form.

Regular verbs: V+ ED

The PII form of most of the regular verbs is created by adding –ed to the verb infinitive. Still, there are cases when:

+ Verbs ending in e: + d

E.g. to smoke → smoked; to live → lived; to dance → danced.

+ Verbs ending in y preceded by a consonant: y→ i +ed

E.g. to study → studied; to hurry → hurried; to marry → married

+ Verbs ending by a consonant preceded by a single vowel, the consonant is doubled before adding –ed.

E.g. to stop → stopped; to travel → travelled; to knit → knitted

Irregular verbs: are formed in different ways, thus, should be learnt by heart. However, it is possible to group them as follows:

+ The Infinitive and the PII are identical.

E.g. to put → put; to hit → hit; to cut → cut

+ The last consonant is changed.

E.g. to send → sent; to build → built; to lend → lent

+ Other forms

E.g. to be → been; to write → written; to go → gone

Use

Part of the passive voice: be/get+ PII

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English for Telecoms Industry. English Section. 2007. 47

E.g. The local network is divided into three parts to reduce the number of cables.

The postcard usually gets delivered every morning.

Part of the perfect form: have + PII

E.g. Satellites have become increasingly important for long distance communication since 1965.

The old mechanical and electromechanical exchanges have now begun to disappear.

Part of the reduced adjective clauses (ref. to Unit 5)

E.g. Almon B. Strowger saw his system installed at La Porte, Indiana.

Transmission on open-wire line was the earliest method used for telephone traffic.

PII can also be used adjectives with either active or passive meanings

E.g. The amplified signals are transmitted to the ground station. (passive meaning)

This system has been in use widely in developed countries. (active meaning)

PRACTICE

Underline and explain the use of the Past Participle in the following sentences.

1. The range covered by ground waves and space waves is limited.

.....................................................................................................................................

2. Advances in computer graphics have brought on the new era in the field of cartoon animation.

.....................................................................................................................................

3. Their networks require less cabling than the star networks of PABXs, and LANs offer distributed control rather than the very centralized systems provided by PABXs

.....................................................................................................................................

4. The first computers were built fifty years ago and it is only in the last thirty or so years that their influence has affected our everyday life.

...................................................................................................................................

5. Fully realizing the dangerous damages possibly caused by Y2K, many governments and companies all over the world have set up detailed action plans and at the same time invested a large amount of money trying to find measures to prevent and overcome this problem.

...............................................................................................................................................

...........................................................................................................................

6. To meet the demand for high reliability, and provide services economically, the public network is being progressively upgraded.

.....................................................................................................................................

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7. Consumers are still waiting for the widespread use of new services such as the video phone which was first demonstrated 30 years ago.

.....................................................................................................................................

8. Within the core network, a technique known as multiplexing is used so only a small number of physical connections are needed between each telephone exchange.

.....................................................................................................................................

.....................................................................................................................................

9. Each analogue voice signal is sampled at a rate 8000 times a second, with some sample represented by eight bits of digital information.

.....................................................................................................................................

10. Communication network should be capable of connecting calls made by subscribers registered in the system to all the terminating subscribers.

.....................................................................................................................................

Presentation 2. PHRASAL VERBS

Study these sentences.

The facilities can be set up differently and have different levels of complexity according to the users’ requirements.

Communications carried out through the interface between men and machines, and between machines are expected to become more popular.

The network consists of a number of components which are interconnected.

The verbs in bold all have the same form: They are a combination of a verb and one (or more) adverb or preposition, without which the meaning of the verb will be different, even senseless in some cases. Therefore, they are called Phrasal Verbs, and the adverbs or prepositions such as in, off, out, etc. are termed Particles.

Phrasal Verbs are formed in some main structures:

Verbs are followed by a particle, and there is no object.

E.g. As soon as one of the subscribers hangs up, the physical link is broken and the call is terminated.

Verbs are followed by a particle and an object.

E.g. The DTE consists of a printer or alphanumeric visual display terminal or a computer.

Verbs are followed by an object and a particle.

E.g. The DTE provides the subscriber with data reception facilities.

Some phrasal verbs can be split and used in both forms.

E.g. When reading a text in ESP you need a dictionary to look up new words.

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= ……….. ………….. to look new words up.

Some verbs are followed by an adverb together with a preposition and an object.

E.g. We are looking forward to the purchase of new photocopiers for all offices in the organization.

Phrasal Verbs may have literal meanings and/ or non-literal meanings. However, meanings of Phrasal Verbs in ESP are mostly literal, i.e. meaning of the verb and that of the particle(s).

Below are some common phrasal verbs given in the book.

act as base sth on carry out get into contact with

break sth into classify sth into connect sth/ sb to get through

provide for link up sb/ sth consist of pick up

result in hang up convert sth into set up

PRACTICE

Fill in the gap with the most appropriate phrasal verb given below. Be sure to put it in the right form.

break sth up build up hang up base sth on consist of

result in make up of carry out set up

1. The call ends just when one of the subscribers .............................

2. Local networks are............................... using aerial or underground cable to meet the demand on operating reliability.

3. An electromechanical exchange is a switching centre and the design of which is............................ thousand moving parts.

4. The Nordic Public Data Network.........................components which are interconnected.

5. Communications network should be capable of ..........................accurate and highly reliable communications.

6. The control part is ..............................circuits and programs which take care of the more intelligent functions in the exchange.

7. The switching matrix includes some cross points .................................a series of horizontal and vertical wires.

8. In the trunk network, all non-local calls are...........................via a GSC and the main network.

9. While speaking, none of the subscriber knows that their speech is ............................ into small batches of time.

10. The marriage of the telecommunications and data processing will ............................... a number of useful products.

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Unit seven

Switching

Part I. Reading comprehension

Read the passage and do the following tasks.

The purpose of every switching system is to establish a temporary circuit or link between

the caller and the subscriber being called. This circuit must be terminated when one of

the subscribers decides to replace his/ her handset. In handling a telephone call, an

exchange performs three essential functions:

* it establishes a path enabling a signal to be transmitted between two subscribers

* it dialogues with other parts of the network

* it processes all other information from the network and decides whether calls can be

established or not.

Two main types of switching technology have evolved : space division switching and

time division switching.The switching matrix consists of a number of crosspoints made

up of a series of horizontal and vertical wires at the intersection of which a relay is

installed. The relay has two positions: on or off.

If two subscribers are to converse, a two-wire channel must be established capable of

transmitting a signal in the 300-3,400 Hz band in both directions. The relays are used to

direct the calls.The physical path of each conversation can be clearly distinguished. As

soon as one of the subscribers hangs up, the physical link is broken and the call is

terminated. The technique used in this exchange is known as space division switching.

Time division switching has begun to replace space division techniques in nearly all the

most modern systems. If we imagine two conversations between four subscribers are

taking place, we can see that they no longer share the physical space in the switching

matrix unless time slots are allocated to each party. During their conversations, none of

the subscribers will, of course, be aware that their speech is being broken into small

batches of time.

When subscriber A speaks to subscriber B, the analogue signals in the 300 - 3,400 Hz

range are transmitted to the exchange, sampled (using Pulse Amplitude Modulation-

PAM) and then transported on the bus before being reconverted into analogue form and

sent on to subscriber B. The sampling rate is determined by using Shannon’s Theory

which states that the sampling frequency must be double the maximum frequency of the

signal. In practice, sampling is done at 8 kHz. The time slot between two samples is thus

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125 microseconds (1 second ÷ 8000 = 0.000125 second). In other words, the signal is

sampled once every 125 microseconds. In the conversation between subscriber A and B,

16,000 samples are transported every second, 8,000 in each direction. When two

conversations take place at the same time, 32,000 samples have to be transported per

second.

This technique, known as time division switching, appears to be very attractive but has

one great drawback: the PAM samples can only be transmitted over relatively short

distances, and the capacity of the bus is limited. When an exchange handles more than 30

simultaneous calls, the PAM sample itself must be encoded so that it can be transmitted

within the exchange without distortion. This is known as digital time division switching

for each sample is encoded into eight bits (one byte).

Vocabulary

analogue signal (np) : tÝn hiÖu t­¬ng tù

distortion (n) : sù mÐo mã, biÕn d¹ng

handle (v) : xö lý, gi¶i quyÕt, thùc hiÖn

temporary circuit (n) : m¹ch t¹m thêi

Task 1: Answer the following questions about the passage.

1. What is the objective of every switching system?

...............................................................................................………..................................

2. Match the exchange functions (a,b,c) with the definitions (i,ii,iii).

a. Control

b. Subscriber connection

c. Signalling

i. Establishing a signalling path between subscribers through an exchange.

ii. Dialoguing with other parts of the network.

iii. Processing network information and deciding whether to establish a call or not.

3. What are the cross points composed of?

................................................................................................................…………...............

4. What is Shannon’s Theory ?

...............................................................................…………................................................

5. What must the PAM be encoded when an exchange handles more than 30

simultaneous calls for?

...................................................................................…………............................................

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Task 2: What do these words in italics in these sentences mean?

1. If two subscribers are to converse, a two-wire...........

a. to ask b. to question c. to communicate

2. ........... the physical link is broken and the call terminated.

a. disturbed b. stopped c. interrupted

3. The sampling rate is determined by using Shannon’s Theory.

a. decided b. controlled c. displayed

4. When two conversations take place at the same time ...............

a. go on b. occur c. continue

5. ............ but has one great drawback.

a. benefit b. disadvantage c. loss

Task 3: Decide whether the following statements are True or False.

1. An exchange establishes a path enabling a signal to be transmitted between

subscribers.

2. The switching matrix includes some cross points made up of a series of

horizontal and vertical wires.

3. The call ends just as one of the subscribers hangs up .

4. While speaking, any subscriber knows that their speech is being broken up into

small batches of time.

5. Time division switching is very attractive and has no disadvantage.

Task 4: Fill in the blanks with no more than 3 words.

1. An exchange performs ............................................... when a telephone call is

handled.

2. Space division switching and ........................................... are two main types of

switching technology which have evolved.

3. The switching matrix composes a number of ..................................... made up of a

series of horizontal and vertical wires at the intersection of which a relay is installed.

4. When two conversations take place at the same time, ....................................... have to

be transported per second.

5. When an exchange handles more than 30 simultaneous calls, the ..................................

must be encoded so that it can be transmitted within the exchange without distortion.

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Task 5: Translate the following paragraph into Vietnamese: “When subscriber A speaks

to speaker B .................. perceived”.

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

...............................................................................................................................................

.................................

Task 6 : Translate the following sentences into Vietnamese

1. Khi thuª bao A ®ang nãi chuyÖn víi thuª bao B, c¶ hai ®Òu kh«ng hÒ biÕt r»ng lêi nãi

cña hä ®ang bÞ ®øt vì thµnh tõng ®o¹n nhá thêi gian.

...............................................................................................................................................

...............................................................................................................

2. Kü thuËt chuyÓn m¹ch b»ng c¬ ®iÖn truyÒn thèng ®ang ®­îc thay thÕ dÇn b»ng kü thuËt

®iÖn tö vµ kü thuËt sè.

...............................................................................................................................

...............................................................................................................................

3. Víi viÖc cæ phÇn ho¸ (equitization) c¸c c«ng ty viÔn th«ng ë ViÖt Nam hiÖn nay, nhu

cÇu cÇn c¸c kü s­ giái ngµnh kü thuËt viÔn th«ng ®ang rÊt lín.

...............................................................................................................................

...............................................................................................................................

4. ThÞ tr­êng dÞch vô viÔn th«ng ë ViÖt Nam ®ang bïng næ (boost), më ra nhiÒu c¬ héi

cho c¸c nhµ cung cÊp dÞch vô.

...............................................................................................................................

..............................................................................................................................

5. C¸c nhµ cung cÊp dÞch vô ®ang c¹nh tranh gay g¾t b»ng nh÷ng ch­¬ng tr×nh khuyÕn

m·i hËu hÜnh (abundant promotion) nh»m thu hót nhiÒu thuª bao h¬n n÷a.

...............................................................................................................................

..............................................................................................................................

Part II. Use of English

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Presentation 1. Time Clause

Study these sentences.

When two conversations take place at the same time, 32,000 samples have to be

transported per second.

This circuit must be terminated when one of the subscribers decides to replace his or

her handset.

The When clauses in bold are termed Adverb Clauses, and as they show the time

relationships between the two clauses in a sentence, they are preferably called

Time Clauses.

There are numerous words used to introduce a Time Clause, such as: after, before,

while, as, by the time, since, until, as soon as, once, whenever, the first time

(that)… Each has a meaning that is notably different from others.

E.g. We subscribed to the VTV Cable as soon as the line was installed in our area.

(almost immediately)

Since mobile phones were first introduced in Viet Nam in the 1990s, they have

become a more and more favourite means of communication.

(starting from the 1990s)

The Time Clause can begin a sentence, separated from the Main Clause by a

comma (,) or end it without changing the meaning of the sentence.

Tenses of the verbs in Time Clauses are normally in Simple Present or Present

Perfect even when the clauses refer to actions or intentions in the future.

E.g. When the Ministry of Post and Telecoms approves the requests made by

VinaPhone, MobiPhone and Vietel, these providers will have new subscription digits;

015, 012, and 016 respectively.

Changing Time Clauses to Modifying Phrases can be done ONLY when the

subjects (the doers) of the two clauses are the same.

E.g.1. After the UK Viewdata has passed an experimental and testing stage, it is now

available in many countries.

After passing an experimental and testing stage, the UK Viewdata is now available in

many countries.

= The UK Viewdata is now available in many countries after passing an experimental

and testing stage.

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Having passed an experimental and testing stage, the UK Viewdata is now available

in many countries.

E.g. 2. A single instruction written in a high-level language usually results in several

instructions when it is transformed into machine code.

A single instruction written in a high-level language usually results in several

instructions when (being) transformed into machine code.

= (Being) transformed into machine code, a single instruction written in a high-level

language usually results in several instructions.

PRACTICE

Ex.1. Change the time clauses in the following sentences when possible.

1. Our grandchildren may laugh when we explain how we used to stand next to a wall in

the kitchen to make a phone call.

…………………………………………………………………………………………...

2. Once mobiles are fitted permanently in a vehicle, they do not rely on separate

batteries.

………………………………………………………………………………………….......

3. Vietnamese viewers in different regions couldn’t watch and join in the same live show

until satellites were used to broadcast TV programmes only about 10 years ago.

………………………………………………………………………………………….......

4. Since INTELSAT invested over three billion US dollars in international

communication services by satellite in 1983, it has been able to handle two thirds of all

international telephone and data communications.

………………………………………………………………………………………….......

………………………………………………………………………………………….......

………………………………………………………………………………………….......

5. Whenever a new version of a game is introduced, it is instantly welcome and tried by

lots of crazy young game players.

………………………………………………………………………………………….......

………………………………………………………………………………………….......

Ex.2. Translate these sentence into English.

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1. KÓ tõ khi ra ®êi vµo n¨m 1965, vÖ tinh ®· ngµy cµng trë nªn quan träng ®èi víi truyÒn

th«ng ®­êng dµi.

………………………………………………………………………………………….......

2. M¸y nh¾n tin ®· nhanh chãng biÕn mÊt ngay khi ®iÖn tho¹i di ®éng ra ®êi.

………………………………………………………………………………………….......

3. Ngµy nay khi mµ th­ ®iÖn tö ®· rÊt phæ biÕn th× ng­êi ta rÊt Ýt khi viÕt th­ tay

mÆc dï mét l¸ th­ viÕt tay ch¾c ch¾n sÏ tá ra ch©n t×nh h¬n.

………………………………………………………………………………………….......

………………………………………………………………………………………….......

4. ChØ sau khi c¸p truyÒn h×nh ®­îc kÐo ®Õn tËn n¬i th× nh÷ng ng­êi d©n khu chung c­

Linh §µm míi cã thÓ xem ®­îc c¸c kªnh cña truyÒn h×nh c¸p.

………………………………………………………………………………………….......

………………………………………………………………………………………….......

5. Phè Lý Nam §Õ ®­îc coi lµ ‘Thung lòng Silicon’ cña Hµ Néi khi mµ ngµy cµng nhiÒu

cöa hµng bu«n b¸n linh kiÖn ®iÖn tö m¸y tÝnh khai tr­¬ng n¬i nµy.

………………………………………………………………………………………….......

………………………………………………………………………………………….......

Presentation 2. expressing quantity and amount

There is a sharp difference in the way to express a quantity of Countable Nouns and an

amount of Uncountable Nouns. Though the terms amount and quantity can be used

interchangeably with both countables and uncountables, their equivalents are not. Study

this table.

Plural Countable Nouns Uncountable Nouns

a (large/ small) quantity/

amount of

a (large/ small) amount/

quantity of

a (great/ large/ good) number of a (great/ good) deal of

(Source: R. Quirk & S. Greenbaum, A University Grammar of English, 1973)

Degrees of indefinite quantity can be presented, using the words (quantifiers) as

follows:

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Plural Countable Nouns Uncountable Nouns too many too much

all (of) most (of) plenty of

a lot of/ lots (not) enough

half (of) some

a few a little very few very little not many not much

hardly any no

How many? How much? (Source: L.G. Alexander, Longman English Grammar, 1988, Longman)

Or the degrees/ scales are more expressive in the following table:

Approx. + Countable Noun + Uncountable Noun 100% 85%

5%

0%

all most

many/a lot of some

several a few few

one of no/ none of

all most

much/a lot of some ___

a little little ___

no/ none of

If you need to count some uncountable nouns, you must add phrasal quantifiers to the nouns, such as: two pieces of (equipment), an item of (work), a bottle of (oil), a pound of (grease), a litre of (petrol), etc.

PRACTICE

Fill in the blanks with the quantifiers listed in the above tables.

1. By the year 2020 _____ _____ _____ digital equipment will be used in each family.

2. When I first bought a digital camera I had very _____ knowledge about how to use it.

3. In principle, when a great _____ of channels are transmitted, a _____ _____ _____ repeaters are required.

4. Because the market is so well-penetrated, there is not _____ scope for adding more subscribers to the network.

5. Digitalization of _____ office equipment is a want to _____ offices.

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6. Our office is equipped with two computers, but _______ of them has been out of order for long.

7. The staff at the university is great in number. What a shame when only _____ have a good command of ICT.

8. ______ of them even do not know how to exploit all properties available in their mobile phones.

9. In the recent years, there have been _______ training classes on ICT. No wonder why illiteracy in ICT is increasing.

10. As mobile phones and service charge are going down in price, _______ _____ the staffs at my university own a mobile phone, _______ even have two or more.

unit eight

Electronical Telecommunications System

Part I. Reading comprehension

Read the passage and do the following tasks.

The technology of electronical telecommunications has continued to advance rapidly ever

since the invention of telegraph and telephone systems that revolutionized the means of

communications about a century ago. Today, electronical telecommunications system is

regarded as the most economical means available for communicating information and

data. Additionally, in parallel with the growth of economic society, the composition of

facilities required for electronical telecommunications has become more complex and

high-tech oriented in order to meet adequately the increasing demand for high-quality

and more advanced telecommunications services. Eventhough the facilities can be set up

differently and have different levels of complexity according to the users’ requirements,

they are basically configured as follows:

Information signal signal Information

Figure 2: Telecommunications Network Composition

Information source

Transmitter

Transmission line (switching)

Receiver

User

Noise Source

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The most commonly used electronical telecommunications system is a telephony

communications system where men are information sources as well as users, and

telephones are used as transmitters/ receivers. Currently, machine (tape)-run information

announcement service is in great demand. This service is characterized by the machine

which acts as information source and by men who serve as users. In addition, machine-

to-machine communications such as data communications are now in service. As shown

in Figure 3a, communications carried out through the interface between men and

machines, and between machines are expected to become more popular.

The conventional electronical communications services are based on the telephone and

the telegraph systems which independently run through the utilization of the subscriber

telephone network and telegraph relay switching network. Nowadays, an increasing

number of highly sophisticated and powerful means such as data and video

communications for transferring various types of information and offering non-telephony

services are being installed and operated, revolutionizing our lives.

Vocabulary

additionally (adv) thªm vµo ®ã

complexity (n) ®é phøc t¹p

even though (adv) mÆc dï

high-tech oriented (a) h­íng c«ng nghÖ cao

in parallel with song song víi

means (n) ph­¬ng tiÖn

revolutionize (v) c¸ch m¹ng ho¸

Task 1: What do these words in italics mean?

1. The technology of electronical telecommunications has continued to advance.……..

a. improve b. develop c. promote

2. ............. signals that are transferred via a transmission line

a. through b. into c. out of

3. Today, the electronical telecommunication system is regarded as the most

economical means available.

a. seen as b. shown as c. considered

4. The most commonly used electronical telecommunications system is a ........

a. worldly b. usually c.widely

5. Currently, machine-run information announcement service is in great demand …

a. occasionally b. frequently c. at present

Task 2: Answer the following questions

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1. What revolutionized the means of communications about one hundred years ago?

..................................................................................................……….................................

2. In which communications system are men regarded as information sources as well as

users?

..............................................................................................................……….....................

3. Which telecommunications service is in great demand now?

.........................................................................................................................………..........

Task 3: Match each of the following terms (1-5) with their definition (a-e)

1. Information source

2. Transmitter

3. Transmission line

4. Receiver

5. User

a. A device or equipment for converting information generated into signals that

are transferred via a transmission line

b. Men or machines that receive information recovered from the receiver.

c. A medium for transferring signals from a transmitter to a receiver. Coaxial

cables, optical cables, space and wave guides are used widely for this purpose.

Signals being sent via a transmission line are subject to interference such as

noise.

d. Men or machines for generating information to be transferred. Information

generated are classified into voice, codes, and video (characters, graphs,

pictures)

e. A device or equipment used to convert signals that have been received into

original signals.

Task 4: Translate this paragraph “The technology of electrical telecommunications...the

users’ requirements” into Vietnamese.

.................................................................................................................................

.....................................................................................................................................

...................................................................................................................................

...................................................................................................................................

..................................................................................................................................

...................................................................................................................................

...............................................................................................................................................

.................................................................................................................

Task 5: Translate the following sentences into English.

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1. C¸c qu¸ tr×nh trao ®æi (c¸c cuéc giao tiÕp) ®­îc tiÕn hµnh th«ng qua giao diÖn gi÷a

ng­êi víi m¸y vµ gi÷a m¸y víi m¸y sÏ trë nªn ngµy cµng th«ng dông h¬n.

...............................................................................................................................................

.......................................................................................................................

2. C¸c dÞch vô viÔn th«ng ®iÖn tö th«ng dông ®­îc dùa trªn c¬ së c¸c hÖ thèng ®iÖn tho¹i

vµ ®iÖn tÝn ho¹t ®éng mét c¸ch ®éc lËp.

...............................................................................................................................................

.......................................................................................................................

Task 6: Read the following text and complete the systems layout diagram.

Each user is connected to the Teletel computer center via the public network. The center

then puts the user into direct contact with the various videotex services that are on offer.

From a technical point of view, these services can be accessed in three different ways:

1. Through software installed in the Teletel center itself.

2. Through software installed in the geographical zone of the test, but not in the

Teletel center itself. The local computers in question are connected to the Teletel

center by leased lines.

3. Through software installed outside the geographical area of the test. These remote

computers are connected to the Teletel center through TRANSPAC, a packet-

switched data transmission network.

In group 2 and 3 the user has the impression that he is in direct contact with the requested

service, but the Teletel center remains in control of the call and can intervene when

requested to connect the subscriber to another service.

The Teletel computer center in Velizy uses a modular minicomputer system to handle

both switching and database functions. The former involves switching subscribers’ calls

to the place where the software is actually installed. The main role of the center is, of

course, to act as an interface for the user, enabling him or her to get into contact with the

exact service required, but it also stores statistical data concerning the use of Teletel

necessary for activities such as billing. The center has been designed to handle 300

simultaneous calls from the 2,500 subscribers.

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Figure 3

Part II. Use of English

Presentation 1. noun formation

A great number of nouns in the English language are formed according to one of the

following rules:

Adding a prefix to the base/ stem (a key/ head noun)

E.g. communication (n) telecommunication (n)

printing (n) misprinting (n)

Adding a suffix to the base

E.g. digital (a) digitalization (n)

deliver (v) delivery (n)

Assigning the base to a different word classwithout changing its form (Zero

Affixation)

E.g. broadcasting (PI) broadcasting (G)

wave (v) wave (n)

Adding one base to another (compounding)

E.g. data (n) + reception (n) = data reception

switching (PI)+ exchange (n) = switching exchange

Note: The meaning of a compound noun should be inferred from the meanings of

each component from right to left, i.e. from the Head Noun backwards.

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E.g. a data circuit concentrator: bé tËp trung m¹ch sè liÖu

space division switching: sù chuyÓn m¹ch ph©n chia thêi gian

Below are common noun-forming suffixes with their usual meanings.

Suffix Meaning Examples

-ance state performance

-dom domain/condition freedom

-ence quality of independence

-er, -or a person who

a thing which

programmer, operator

compiler, accumulator

-ess female actress, lioness

-hood status neighbourhood, boyhood

-ist, -yst a person who analyst, typist

-ian pertaining to electrician

-ity state, quality electricity

-ion action/state conversion

-ing activity multiplexing

-ism condition, state magnetism

-ence quality of independence

-let small, unimportant booklet, piglet

-ment state, action measurement

-ness condition of readiness

-(e)ry behaviour

action

collectivity

slavery

delivery

machinery

-ship condition/state relationship

-tion, -ation the act of compilation

PRACTICE

Recognize how these nouns/ noun phrases are formed by splitting them into each

particle and translate them into Vietnamese.

E.g. invention = invent/ ion: ph¸t minh

telecommunication service = tele/ communica/ tion + service: dÞch vô viÔn th«ng

1. telephony communications system =

2. telegraph relay switching network =

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3. time division multiplexed high speed links =

4. data reception facilities =

5. solid state semi-conductor technology =

6. terminal repeater stations =

7. ship-to-shore radio =

8. air-traffic controller =

9. digital time division switching =

Presentation 2. expressing purposes and reasons

expressing purposes

Study these sentences.

A PABX can normally be easily upgraded through software modifications to provide new

facilities for the office of the future.

The LAN frees the PABX for other functions.

The purpose of every switching system is to establish a temporary circuit or link

between the caller and the subscriber being called.

The composition of facilities required for electronical telecommunications has become

more complex and high-tech oriented in order to meet adequately the increasing

demand for high-quality and more advanced telecommunications services.

The phrases in bold are used to express the purposes of the action or status

denoted in the main clauses preceding them.

Popular expressions can be listed as follows:

o S + V + to V(inf.)

o S + V + in order/ so as to V (inf.)

o S + V + for + NP

o S + V + so that + S’ + V’ (will/ would or can/ could + inf.)

o S + V + in order that + S’ + V’ (may/ might or shall/ should + inf.)

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o The purpose of + NP + is + to V (inf.)

Note: Verb phrases that express purposes such as to V (inf.) and in order to V (inf.) can

begin a sentence or end it.

E.g. To realize the above, the switching system network should be designed and

then, set up adequately…

Expressions of purposes are to answer questions: What … for?/ Why?

expressing reasons/causes

Study these sentences.

Public Data Networks (PDN) can avoid the limitations of speed of transmission over the

switched public telephone because they are designed to monitor the set-up and clear-

down of data calls.

Strowger, an undertaker from Kansas City, found his business was becoming less and

less profitable because the operator always connected calls intended for him to other

undertakers.

The clauses in bold are used to express the reason/ cause that leads to the status or

action denoted in the main clauses.

Clauses of reasons are usually introduced by as, because, since, for. They can

begin a sentence, separated from the main clauses by a comma (,), or end it.

E.g. As the telecoms service providers constantly offer promotion prices, more and more

people use mobile phones.

= More and more people use mobile phones as the telecoms service providers

constantly offer promotion prices.

Reasons/ causes can also be expressed by: because of + NP

due to + NP

E.g. The shipment of exchange components is late due to a heavy storm off shore.

….. because of …..

Compare Purposes with Reasons/ Causes

E.g. Why are there more and more people using mobile phones?

- because mobile phones are cheap and easy to use. (reasons)

- so that people can communicate faster and more conveniently. (purposes)

The distinction between Purposes and Reasons/ Causes, therefore, can be modelled like

this: Reasons/ causes Action/ Status Purposes

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PRACTICE

Complete the following sentences with expressions of purposes or reasons.

1. The old mechanical and electromechanical exchanges have now begun to disappear….

……………………………………………………………………………………………...

2. A common control system was used in crossed bar exchanges…………………………

……………………………………………………………………………………………...

3. Telefax has its biggest market in Japan …………………………………………………

……………………………………………………………………………………………...

4. Analogue exchanges are costly to install and maintain …………………………………

……………………………………………………………………………………………...

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further reading

Reading 1

Development of Telephone Exchanges

On March 10th 1876, in Boston America, Alexander Graham Bell spoke the first

recognizable words over what was certainly his most famous invention, the telephone.

“Mr. Watson, come here. I want you,” he called out to an astonished assistant.

It quickly became necessary to link up people using the new invention. This was done

through the telephone exchange. In the first simple exchanges, all calls were handled

manually by the operator. Using the switchboard in front of her, she plugged the line of

the subscriber calling her into the line of the subscriber being asked for.

The idea of an automatic exchange was soon suggested. In 1892, three years after

patenting his ideas, Almon B. Strowger saw his system installed at La Porte, Indiana.

Strowger, an undertaker from Kansas City, found his business was becoming less and

less profitable because the operator always connected calls intended for him to other

undertakers.

Strowger’s automatic exchange underwent several modifications over the next fifty years,

but the principle has remained the same ever since. It is known as the ‘step-by-step’

system and there are still thousands of Strowger exchanges in service throughout the

world today.

The next generation of the exchanges was first developed in Sweden. Crossbar

exchanges, as they are called, consist of a series of vertically and horizontally crossed

bars. For the first time a common control system was used. This made crossed bar

exchanges cheaper than Strowger, for each selector could now carry up to ten calls. They

were not as noisy as Strowger, either. These exchanges are electro-mechanically

operated, using electromagnets.

In 1948, the invention of the transistor at Bell Telephone Laboratories led to a revolution

in electronics and to the creation of semi-electronic telephone exchanges.

The old mechanical and electromechanical exchanges have now begun to disappear, and

since the 1970s they have started to be replaced by exchanges built around electronic

components. The latest digital switching centres have several advantages over other types

of exchanges, for they provide: a substantial reduction in equipment cost; a large

reduction in equipment size; shorter procurement times; shorter installation and

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commissioning times; greater reliability and reduced running costs; new services for the

customer; and new facilities for the administration.

Answer the following questions.

1. What do Americans call a telephone exchange?

..............................................................................................................................................

2. Who invented the telephone? When and Where?

..............................................................................................................................................

3. What did the first operators have to do?

..............................................................................................................................................

4. Why did Strowger invent the automatic telephone exchange?

..............................................................................................................................................

5. What is ‘crossed bar’ system?

..............................................................................................................................................

6. What advantages does crossed bar offer over Strowger?

..............................................................................................................................................

7. What important development took place in 1948?

..............................................................................................................................................

8. What are mechanical and electromechanical exchanges being replaced by?

..............................................................................................................................................

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Reading 2

International Telecoms

In the century since the birth of the telephone, the world telecommunications network has

evolved both in size, slowly at first and then with astonishing speed, and in the

techniques used to transmit information. The development has, however, been very

uneven for, by 1983, three quarters of the total number of telephone sets had been

installed in just nine countries. These are the U.S.A with 180 million telephones, Japan

with 59 million, West Germany with 28 million, the UK and France with 27 million each,

Italy with 19 million, Canada with 16 million, Spain with 13 million and Australia with 8

million.

In terms of continents, North America had 199 million telephones of all types in 1982

(38.1% of the world total), Central and South America 24 million (4.4%), Europe 203

million (39%), Asia 81 million (15.5%) with Japan accounting for 59 million (11.2% of

the world total). Oceania had 1.8% of the total (10 million phones) and, finally, Africa

had 6.5 million (1.2% of the world total)

The eastern block countries are not included into these figures, but at the beginning of

1982 the USSR is estimated to have had 25 million sets, East Germany, Poland and

Czechoslovakia just over 3 million each and Yugoslavia a little over 2 million.

As the ITU declared when organizing ‘World Communication Year: 1983’,

“Communications, which come immediately after food, housing and energy in the list of

things which are indispensable for the survival of Humanity, make up the nervous system

of today’s world and constantly remind us that Humanity is one.” As we can see from the

statistics, some continents have an extremely small number of telephones, a fact that

likely to restrict socio-economic development, while in other countries telephones are so

common that normal everyday existence without them seems unthinkable. Countries like

Sweden and the USA have almost one telephone set for every inhabitant and their

populations instinctively use the telephone in a very wide range of situations. The

concept of “wired city” in which anyone can instantly talk to almost anyone else by using

the telephone or some other forms of electronic devices has become a reality in countries

such as these.

The importance of telecommunication services in the infrastructure of a country is

universally recognized. But what is their internal order of importance? Arthur C. Clarke,

author of 2001- A Space of Odyssey and the first person to conceive the idea of

geosynchronous satellites, tried to answer this question in a recent address. He listed a

number of services in the following order: the telephone, radio and TV, telex and, finally,

data networks.

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‘A reliable telephone system must surely have the first priority’, said Clarke, ‘for it

affects every aspect of life ... personal, business, and government. It will be a long time

but not as long as you think, before every body has a telephone. But with a telephone in

every village we can have the next beast thing’. He pointed our that with the introduction

of International Direct Dialing in recent years, the power of the state to control news was

broken. Private individuals can now speak to each other across frontiers.

Answer the following questions.

1. Which continent owns the most telephones of all types in 1982?

..........................................................................................………….....................................

2. Where does communications rank in the list of indispensable things for the human

beings?

......................................................................................................……….............................

3. According to the text, what is “wired city” mean?

..................................................................................................................……….................

4. What order did Arthur C. Clarke list telex, radio and T.V, data networks and

telephones?

........................................................................................................................………...........

5. Why will data services be widely used in the near future?

.................................................................................................……….................................

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Reading 3

Local Area Networks (LANs)

Local Area Networks (LANs) may be defined as transmission and transmitting systems

that provide high-speed communication between devices located on a single site. This

could be an office complex, an individual estate, a college campus or any closely linked

grouped buildings in which a variety of workstations need to communicate with each

other. A typical LAN may cover a distance ranging from a few metres to around ten

kilometers. As much of our daily work in the office involves using different kinds of

communication media, LANs have been seen to be particularly useful in the fields of

office automation (OA) and distributed data processing (DDP). Several studies have

shown that there are four fundamental levels of communication in office systems:

1. Communication within a group, which could be a particular department in a

company. The distance of transmission ranges from a few meters to about one

hundred meters.

2. Communication with other internal groups or departments in the same company.

The transmission distance ranges from a few hundred meters to perhaps two or

three kilometers.

3. Communication with branch offices of the same company. The distance here

ranges from a few dozen kilometers to hundreds of kilometers.

4. Communication with the outside world. The transmission distance ranges from a

few kilometers to thousands of kilometers.

Typically, we find that about 50% of all office communication circulates within one

geographic site and that 70% of all communication circulates within the same company.

Only 30% ever goes beyond the company into the outside world, to customers and

suppliers for example.

Many large companies, or groups working on the same site, are being faced with the

choice of continuing with their own PABXs, which may be electromechanical or

electronic, or of installing a LAN. Installing a LAN is certainly very expensive but offers

a great variety of advantages over a PABX. Suppliers of LANs have been offering

systems based on two major classes of architecture; the ring and bus topologies.

A third solution that is also sometimes suggested is based on the classic star network, in

which a central a processor controls all other nodes in a master/slave manner.

The central processing unit (CPU) in ring and bus topologies can be located anywhere in

the network, making for truly decentralized processing, whereas it controls every

operation in a star network. In contrast to LAN suppliers, the effort of PABX suppliers

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has been placed, for the main part, on replacing electromechanical systems with modern,

electronic PABXs where the customer’s requirements have been almost exclusive for

voice-only systems. The late entry of PABX suppliers into the OA market has been seen

by many as the chasing of a new expanding market with second best technology.

So which is the better for the office, a PABX or a LAN system?

A lot obviously depends on the size and specific needs of each company, but LAN

topology and architecture seem to be more suitable for levels One and Two because of

the very high data rates, high occupancy and transaction levels that are involved in.

PABXs, on the other hand, seem to be more suitable for levels Three and Four, where

communication over longer distances is required.

Other arguments in favour of the PABX are that most people are already familiar with it

and know how to use all its facilities. A PABX can normally be easily upgraded through

software modifications to provide new facilities for the office of the future. It also offers

full access to all national telecommunication services and the electronic PABX gives the

user features such as call detail recording. The PABX has single wire connectivity and

cabling probably already runs from the PABX to every workstation in the company. A

final argument is that most users have limited budgets and prefer to continue with a

technology that has been tried and tested, especially as they consider that voice traffic,

rather than data, will remain the dominant form of communication.

The principal argument in favour of LANs is their ability to handle large amounts of data

at high speed. Also their networks, either ring or bus, require less cabling than the star

networks of PABXs, and LANs offer distributed control rather than the very centralized

systems provided by PABXs. This gives LANs more power and flexibility. It is also

easier to share specialized resources with a LAN and different terminals can be connected

more economically than on a PABX. Finally, the LAN frees the PABX for other

functions.

Against the LAN, we can argue that it is costly to install; it is limited in communication

distance; there is a lack of privacy and a relatively small bandwidth; and it can only

accommodate a limited number of terminals. For some operations a LAN may also be

less reliable than a PABX.

Since LANs appear to be particularly well suited to the electronic office they will

certainly continue to develop in different forms using transmission media (coaxial cable

and/or optical fibres) which meet the specific requirements and technical possibilities of

individual companies in terms of architecture and investment.

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Answer the following questions.

1. How does the text defined a LAN?

..................................................................................................……….................................

2. Give four examples of places where LANs could be installed?

...................................................................................................………................................

3. What are the two major classes of LAN architecture?

.............................................................................................................………......................

4. What market have PABX suppliers been aiming at ?

...................................................................................………................................................

5. Give five examples of a PABX over a LAN.

...............................................................................………....................................................

6. Give six examples of a LAN over a PABX.

.....................................................................................………..............................................

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Tµi liÖu tham kh¶o

Alexander, L.G. 1988. Longman English Grammar. Longman.

Betty, S.A. 1999. Understanding and Using English Grammar, Third Edition. Longman

Bé m«n Anh v¨n. 2000. TuyÓn tËp thuËt ng÷ tiÕng Anh chuyªn ngµnh §iÖn-§iÖn tö. §Ò

tµi nghiªn cøu khoa häc sè 29/CB-2000. Tr­êng §¹i häc Giao th«ng VËn t¶i.

Dave, W. 1995. Collins Cobuild Student’s Grammar. Harper Collins Publisher.

Jeremy, C., Rod Revell, Ian Simpson, Trish Scott & Derek Utley. 1986. English for

Telecommunications Industry. Oxford University Press.

NguyÔn ThÞ Thu H­¬ng & Ph¹m Thu Thuû. 2001. Bµi gi¶ng TiÕng Anh chuyªn ngµnh

Tin häc. §¹i häc Giao th«ng VËn t¶i

Robert, J.D.1994. Graded Exercises in English. Prentice Hall.

Quirk, R. & Greenbaum, S. 1973. A University Grammar of English.