V. Match each word or word combinations with the correct equivalent.

destination	частота
medium	жила
twisted-pair wire	скручивать
frequency	пропускная способность
avoid	среда, средство
layer	полоса пропускания
strand	адресат информации
twist	избегать
bandwidth	слой, уровень
capacity	витая пара

 

VI.Arrange in pairs the words and word-combinations with a) similar meaning, b) contrary meaning:

a) ground, immune, repeater station, earth, situate, conventional, non-susceptible, obstacle, locate, obstruction, relay station, common;

b) invisible, inside, wireless, internal, expensive, outside, visible, wired, cheap, external.

VII. In the text of task XVIII find the word derived from the verb to transmit. Name other derivatives of this verb.

VIII. Read the text and choose the most suitable title:

1.Communications channels.

2. Wireless Communication.

3. Types of Cables.

 

1. A communications channel is the physical medium, through which information travels from its source to its destination. A communications channel is rated by its channel capacity or bandwidth and measured in bits per second.

2. Cable. Cable includes twisted-pair wire and coaxial cable. Twisted-pair wire consists of two strands of insulated copper wire, twisted around each other and covered in another layer of plastic insulation. Much of the world is served by twisted-pair wire, both for voice messages and for modem-transmitted computer data. Coaxial cable consists of insulated copper wire wrapped in a metal shield, then in an external cover. The shield is grounded and prevents the cable from picking up or emitting electrical noise, thus, coaxial cable is much better at resisting noise than twisted-pair wiring.

3. Fiber-optic cable. Unlike cables that carry data as electrical signals at radio frequencies, fiber-optic (FO) cable uses infrared or visible light to transmit information as laser-generated pulses of light. It carries much more signals than conventional copper wire, which makes transmission of information faster and less expensive than copper wire transmission, and is totally immune to electromagnetic interference.

4. Wireless communication. There are many situations in which it is difficult to lay wires. Data can be transmitted via electromagnetic waves and satellite links. Microwave earth stations transmit voice and data through the atmosphere as high-frequency radio waves, even if slower than via fiber-optic cable. As microwave signals travel in a straight line from source to destination, to avoid obstructions and the curvature of the earth, they need to be beamed several times by repeater stations situated on top of high places so that the antennas are in line of sight of each other, or by communications satellites. At very high frequencies (VHF) and above, many communications circuits use satellites in geostationary orbits (GEO) around the earth.

IX. In passage 1 find the definition of a communications channel and its main features.

X. Look through passage 2 and explain the difference between twisted-pair and coaxial cable.

XI. Read passage 3 and name the advantages of fiber-optic cable as compared to copper cable.

XII. Read the second sentence of passage 4 and divide it into sense groups. Define the dependency relations between them.

XIII. Say whether the following statements are true (T) or false (F). Correct the false ones.

1. Twisted-pair wire is used only for transmitting voice messages.

2. Coaxial cables are more susceptible to electromagnetic interference.

3. Fiber-optic cables are used to transmit data in the form of electric pulses.

4. Wireless communication is greatly influenced by obstacles, so microwave signals need amplification.

XIV.Translate passage 4 into Russian.

Предлоги

8.1 Предлоги, указывающие на местоположение

8.2 Предлоги, указывающие на время

 

Запомните значение следующих предлогов
FOR	ДЛЯ
BY	(ЧЕМ)
WITH	С
WITHOUT	БЕЗ
AS	КАК
OF	(ЧЕГО, КОГО)
ON = UPON	НА