UNIT FOURTEEN

■ decade – десятилетие ■ light pulse – световой импульс ■ to transmit information – передавать информацию ■ lightwave communications system – система связи с использованием световых волн ■ hair-thin glass fiber – стекловолокно толщиной в человеческий волос ■ voice signal – речевой сигнал ■ capacity – мощность ■ contents – содержание ■ high-speed data signal – высокоскоростной сигнал данных ■ accommodate – включать, охватывать ■conventional – традиционный, обычный ■ copper wire – медная проволока ■ to substitute for – заменять, замещать ■ to install – устанавливать ■ electromagnetic interference – электромагнитная помеха (интерференция) ■ lightguide cable – световодный кабель ■ carrier system – многоканальная система связи ■ signal regenerator – регенератор сигнала ■ electrical digital carrier system – система электрической многоканальной цифровой связи ■ equipment оборудование ■ protection – защита

LESSON TWO

I. Read text A. Try to understand all details. Use a dictionary if necessary:

Text A

Modern Light-Wave Communications Technology

1. Some time ago, the concept of using light pulses instead of electrical signals¹ to transmit information was only that – a concept. Today, lightwave communications systems are among the most sophisticated transmission systems in the telecommunications network. They are at once efficient, versatile and relatively inexpensive to install and maintain.

2. The efficiency of lightwave systems is perhaps their most renowned quality². They carry enormous amounts of information over long distances at very high speeds. Consider, for example, the speed and capacity of the Bell System's long distance lightwave system. Light pulsing through a single, hair-thin glass fiber in this system can transmit the entire contents of Webster's unabridged dictionary⁴ – more than 2700 pages – over thousands of miles in only six seconds.

3. No less impressive than this tremendous speed and capacity is the versatility of light-wave systems. Because they are digital systems, they can transmit easily any of these types of information: voice signals, high-speed data signals, and television signals. Without undermining quality or efficiency, a single system can accommodate thousands of telephone conversations, and alternately handle data or video signals.

4. Finally, lightwave systems are inexpensive to install and operate compared to their wire-and-cable counterparts. Moreover, they allow considerable savings.

5. The reasons for such savings stem from the technology of lightwave communications. Conventional telecommunications transmission is based on the conduction of electrons through metal (usually copper wires). Lightwave systems, however, substitute protons for electrons and glass fibers for copper. These technological differences translate into big savings⁵, the most significant of which is in construction costs. Because lightguide cables are only a fraction of the diameter and weight⁶ of copper cables, they are easy to handle and take up far less space. They can be installed in existing underground ducts and rights-of-way⁷, sometimes right next to copper cables.

6. In addition, lightwave systems eliminate certain equipment and operating costs. They are immune to electromagnetic interference⁸, and therefore require no protection from it. Also, light can travel much farther through lightwave cables without regeneration than can electrons through copper carrier systems. This is because the light encounters little resistance from the very pure glass fibers through which it travels. Lightwave systems require significantly fewer signal regenerators than do electrical digital carrier systems: typically one every ten miles instead of one every mile.

Notes

1. the concept of using light pulses instead of electrical signals – идея использования световых импульсов вместо электрических сигналов

2. their most renowned quality – их самое известное свойство

3. over long distances – на большие расстояния

4. the entire contents of Webster's unabridged dictionary – полное содержание неадаптированного словаря Вебстера

5. translate into big savings – приводят к большой экономии

6. only a fraction of the diameter and weight – только частица в диаметре и по весу

7 right-of-way – полоса отчуждения

8. are immune to electromagnetic interference – невосприимчивы к электромагнитной интерференции

II. Say whether the following statements are true or false:

1. The concept of using light pulses instead of electrical signals to transmit information is not new. 2. The efficiency of lightwave systems is their most renowned quality. 3. Lightwave systems can transmit various types of information: voice signals, high-speed data signals, and television signals. 4. Conventional telecommunications transmission is not based on the conduction of electrons through metal.

III. Answer the following questions on paragraph 1:

1. Is the idea of using light pulses instead of electrical signals to transmit information new?

2. Do lightwave communications systems belong to the most sophisticated transmission systems?

3. What are the qualities of lightwave communications systems?

IV. Find the place in paragraph 2 containing information about the possibility to transmit the entire contents of Webster's dictionary over thousands of miles in only six seconds.

V. In paragraphs 3 and 4 find the English equivalents of the following words and word combinations:

огромная скорость, по сравнению с, разносторонность; система дискретной (цифровой) связи, речевой сигнал, сигнал данных, видеосигнал, устанавливать, качество, эффективность.

VI.Translate paragraph 5 into Russian.

VII.Read paragraph 6 and say:

a) whether lightwave systems eliminate certain equipment and operating costs; b) whether they are immune (невосприимчивы) to electromagnetic interference; c) whether light can travel much farther through lightguide cables without regeneration than electrons; d)whether lightwave systems require significantly fewer signal regenerators than electrical digital carrier systems.

VIII. Write out of the text words, word combinations for describing advantages of light wave systems. Use these words for describing these advantages to your group-mate.

IX. Describe the technological differences between conventional telecommunications transmission and lightwave systems.

X. Divide text A into logical parts and find topical sentences in each part.

XI. Fill in the boxes of the following logical diagram of text A with Russian equivalents:

transmission system

voice signals

high-speed data signals

television signals

XII. Read text A again. Make a list of key fragments picked out from each successive paragraph. Rearrange the key fragments, make a plan and then use it to write a précis. The number of sentences in your précis should be approximately the same as the number of paragraphs in the original.

LESSON THREE

I. Look through the list of the English words and their Russian equivalents facilitating reading text B:

fiber – волокно; strand – прядь, жила, нитка; breakthrough – достижение, открытие; transparent – прозрачный; call – телефонный разговор, заказ; вызов; immune – устойчивый, невосприимчивый; interference – помеха, вмешательство; интерференция; to affect – влиять, воздействовать; to sweep through – охватывать; to handle – обращаться, управлять; core – стержень, сердцевина; to reflect – отражать; ingredient – компонент, составная часть; to draw (drew, drawn) – тянуть, вытягивать; to coat – наносить покрытие; grain – крупица, зерно; application – применение.

 

П.Read text В and entitle it. Compare your title with the one given by the author (see the key on page the author (see the key on page 169)

 

Text B

Optical fibres, hair-thin strands of pure glass carrying information as pulses of light¹, have been described as "probably the biggest breakthrough in telecommunications since the invention of the telephone". All kinds of communications can be carried along the same optical fibre cable – speech, text, photos, drawings, music, computer data, etc. – at higher speeds than have been previously possible.

The fibres, made from glass so pure that a block of it 20 km thick would theoretically be as transparent as a window pane², have many advantages over metal wires. Small, light and easy to handle, they are made from an abundant raw material, sand. They can carry the same number of telephone calls as metal cables ten times as thick – dozens of fibres, carrying around, 100,000 telephone calls, could all pass through the eye of a needle⁴, at the same time – and they are immune to electrical interference which affects the quality of calls. An optical fibre cable the thickness of a finger could bring a hundred TV channels to a receiver.

The tiny strands are playing a key role⁵ in the digital revolution which is sweeping through modern telecommunications. The telecommunications network developed for the telephone used a system which turned the air pressure waves created by speech into continuous and variable "analogues" of electrical waves and turned them back to speech at the receiver. Expensive conversion equipment or separate networks were needed to handle text, TV or computer data. In the digital world, however, all forms of information are translated into bits⁶, the standard international language of today's computers, and represented as pulses of light. Information in this form can be processed easily and sent anywhere in seconds in a single multi-purpose network. Optical fibres are ideal for digital working and open the door to a host of services not possible on an analogue system.

Each strand of fibre consists of an inner core⁷ to channel the light and an outer cladding⁸ to keep it in by reflecting it back along the core. To make the glass for the fibres, the ingredients are deposited as gases on the inside of a hollow silica tube⁹ at temperatures of around 2000°C. The tube is collapsed under intense heat to form a solid glass rod¹⁰ about I cm in diameter which already has the structure of the fibre which will be drawn from it. The rod is then loaded into a furnace, drawn into fibre and coated with resin to protect it and increase its flexibility. Tiny crystals the size of grain of salt are used to produce the light which carries information along the fibres. This passes through a lens into the fibre. At the other end a receiver reverses the process and turns each light pulse into an electrical sign. Optical fibres will have countless applications¹¹ in tomorrow's "information society".