Exercises:

1. Give Russian equivalents of the following phrases:

Data must move through something; the atmosphere is all transmission media; before the data can be communicated; the three basic forms; affects the maximum rate; move data relatively slowly; transmit large volumes of data at high speeds.

2. Say if the following sentences are true or false.

1. But after the data can be communicated, it must be converted into a form for communication. 2. The three basic forms into which data can’t be converted for communication. 3. Obviously, some situations require that data be moved as fast as possible; others don’t. 4. Channels that move data relatively slowly, like telegraph lines, aren’t narrowband channels. 5. Most telephone lines are voiceband channels, and they have a wider bandwidth than narrowband channels.

3. Insert missing words, use the text’s vocabulary:

1. But before the data can be communicated, it must be … into a form for communication. 2. The … basic forms into which data can be converted for communication. 3. The … or … of communications affects the maximum rate at which data can be moved through the channel and the level of noise that will exist. 4. Broadband channels (like … cable, fiber optic cable, microwave circuits, and … systems) transmit large volumes of data at high speeds. 5. The transmission … used to support data transmission are telephone lines, coaxial cables, microwave systems, and fiber optic cables.

4. Translate these sentences into your native language:

1. To get from here to there, data must move through something: a telephone line, a cable, or the atmosphere is all transmission media, or channels. 2. The form or method of communications affects the maximum rate at which data can be moved through the channel and the level of noise that will exist- for example, light pulses travel faster than electromagnetic waves, and some types of satellite transmission systems are less noisy than transmission over telephone wires. 3. Broadband channels (like coaxial cable, fiber optic cable, microwave circuits, and satellite systems) transmit large volumes of data at high speeds. 4. Understanding how to these media function will help you sort out the various rates and charges for them and determine which is the most appropriate in a given situation Understanding how to these media function will help you sort out the various rates and charges for them and determine which is the most appropriate in a given situation

5. Retell the text.

Text 14

Microwave Systems

Words and word combinations:

Using wire or cable – использующий провод или кабель

radio waves – радио волны

a higher frequency range – более высокий диапазон частоты

as ‘line of sight’ signals – линия подобных сигналов

the curvature of the earth – кривизна земной поверхности

microwave towers – микроволновые вышки

relay stations – релейные станции

the earth typically curves – типичные изгибы земной поверхности

a dish-or a horn-shaped antenna – антенна в форме тарелки или рожка

the signal strength – усиливает сигнал

the primary advantage of using – основное преимущество использования

must physically connect – должен физически соединен

have to be satisfied – вынужден будет удовлетвориться

Instead of using wire or cable, microwave systems use the atmosphere as the medium through which to transmit signals. These systems are extensively used for high-volume as well as long-distance communication of both data and voice in the form of electromagnetic waves similar to radio waves but in a higher frequency range. Microwave signals are often referred to as ‘line of sight’ signals because they cannot bend around the curvature of the earth; instead, they must be relayed from point to point by microwave towers, or relay stations, placed 20 to 30 miles apart.

T he distance between the towers depends on the curvature of the surface terrain in the vicinity. The surface of the earth typically curves about 8 inches every mile. The towers have either a dish-or a horn-shaped antenna. The size of the antenna varies according to the distance the signals must cover. A long-distance antenna could easily be 10 feet or large enough for small distances. Each tower facility receives incoming traffic,

(a) Microwave line-of-sight links

boosts the signal strength, and sends the signal to the next station.

T he primary advantage of using microwaves systems for voice and data communications are that direct cabling is not required. (Obviously, telephone lines and coaxial cable must physically connect all points in a communications system) more than one half of the telephone system now uses microwave transmission. However, the saturation of the airwaves with microwave

transmissions has reached the point where future needs will have to be satisfied by other communications methods, such as fiber optic cables or satellite systems.

(b) Microwave tower