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Data Transmission Media



Words and word combinations:

To get from here to there – доставлять от сюда туда

data must move through – данные должны двигаться через

electrical pulses or charges – электрические пульсы или заряды

electromagnetic waves – электромагнитные волны

pulses of light – электропульсация

the form or method of communications – формы и методы связи

less noisy – менее шумные

voiceband channels – каналы голосового диапазона

wider bandwidth – широкополосный диапазон

narrowband channels – каналы узкого диапазона

to support data transmission – поддерживать передачу данных

the most appropriate – наиболее соответствующий

To get from here to there, data must move through something. A telephone line, a cable, or the atmosphere are all transmission media, or channels. But before the data can be communicated, it must be converted into a form for communication. The three basic forms into which data can be converted for communication are:

· Electrical pulses or charges (used to transmit voice and data over telephone lines)

· Electromagnetic waves (similar to radio waves).

· Pulses of light.

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. Obviously, some situations require that data be moved as fast as possible; others don’t. Channels that move data relatively slowly, like telegraph lines, are narrowband channels. Most telephone lines are voiceband channels, and they have a wider bandwidth than narrowband channels. Broadband channels (like coaxial cable, fiber optic cable, microwave circuits, and satellite systems) transmit large volumes of data at high speeds.

The transmission media used to support data transmission are telephone lines, coaxial cables, microwave systems, and fiber optic cables. 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.

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

 

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.

The 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.

The 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

Exercises:

1. Give Russian equivalents of the following phrases:

Use the atmosphere as the medium; to transmit signals; extensively used for high-volume; electromagnetic waves similar to radio waves; must be relayed from point to point; placed 20 to 30 miles apart; size of the antenna varies; sends the signal to the next station; by other communications methods.

 

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

1. Instead of using wire or cable, microwave systems use the atmosphere as the medium through which to transmit signals. 2. Microwave signals aren’t often referred to as ‘line of sight’ signals because they cannot bend around the curvature of the earth. 3. The distance between the towers depends on the curvature of the surface terrain in the vicinity. 4. A long-distance antenna could easily be 10 feet or large enough for small distances. 5. Obviously, telephone lines and coaxial cable needn’t physically connect all points in a communications system.

 

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

1. These systems are … 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. 2. The distance between the … depends on the curvature of the surface terrain in the vicinity. 3. The size of the antenna … according to the distance the signals must cover. 4. Each tower facility … incoming traffic, boosts the signal strength, and sends the signal to the next station. 5. The primary advantage of using … systems for voice and data communications is that direct cabling is not required.

 

4. Translate these sentences into your native language:

1. Instead of using wire or cable, microwave systems use the atmosphere as the medium through which to transmit signals. 2. 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. 3. A long-distance antenna could easily be 10 feet or large enough for small distances. 4. Each tower facility receives incoming traffic, boosts the signal strength, and sends the signal to the next station. 5. 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 fiber optic cables or satellite systems.

Retell the text.

Text 15

Satellite System

 

Words and word combinations:

Gigahertz range – предел гигагерц

billions of cycles per a second – биллионы циклов в секунду

a geosynchronous orbit – околоземная орбита

the earth’s surface – поверхность земли

a solar-powered electronic device – электронный прибор на солнечной энергии

retransmit signals – сигналы посланные обратно

the amount of area – большой район

the entire surface of the earth – вся поверхность земли

with some overlap – немного заходящий один на другой

signals can weaken – сигналы могут ослабевать

weather conditions and solar activity –

can cause noise interference – может быть причиной шумовых помех

a satellite is useful for only – спутник является пригодным только

anyone can listen in on satellite signals – любой может слышать спутниковые сигналы

must be sent in a secret, or encrypted form – должны быть отправлены в секретной или зашифрованной форме

 

Satellite communications systems transmit signals in the gigahertz range- billions of cycles per a second. The satellite must be placed in a geosynchronous orbit, 22,300 miles above the earth’s surface, so it revolves once a day the earth. To an observer, it appears to be fixed over one region at all times. A satellite is a solar-powered electronic device that has up 100 transponders (a transponder is a small, specialized radio) that receive, amplify, and retransmit signals; the satellite acts as a relay station between satellite transmissions stations on the ground(called earth stations). Although establishing satellite systems is costly (owing to the cost of a satellite and the problems associated with getting it into orbit above the earth’s surface and compensating for failures), satellite communications systems have become the most popular and cost-effective method for moving large quantities of data over long distances.

The primary advantage of satellite communications is the amount of area that can be covered by a single satellite. Three satellites placed in particular orbits can cover the entire surface of the earth, with some overlap.

However, satellite transmission does have some problems: (1) the signals can weaken over the long distances, and weather conditions and solar activity can cause noise interference. (2) A satellite is useful for only 7 to 10 years, after which it loses its orbit. (3) Anyone can listen in on satellite signals, so sensitive data must be sent in a secret, or encrypted, form. (4) Depending on the satellite’s transmission frequency, microwave stations on earth can ‘jam’, or prevent, transmission by operating at the same frequency.

Large companies with offices around the world benefit the most from satellite communication.

Exercises:

1. Give Russian equivalents of the following phrases:

Transmit signals in the gigahertz range- billions of cycles per a second; 22,300 miles above the earth’s surface; to be fixed over one region at all times; a transponder is a small, specialized radio; satellite’s transmission frequency.

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

1. The satellite needn’t be placed in a geosynchronous orbit, 22,300 miles above the earth’s surface, so it revolves once a day the earth. 2. The primary advantage of satellite communications is the amount of area that can be covered by a single satellite. 3. Four satellites placed in particular orbits can cover the entire surface of the earth, with some overlap. 4. Large companies with offices around the world benefit the most from satellite communication.5. Although establishing satellite systems isn’t costly (owing to the cost of a satellite and the problems associated with getting it into orbit above the earth’s surface and compensating for failures)

 

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

1. Satellite communications … transmit signals in the gigahertz range- billions of cycles per a second. 2. A satellite is a solar-powered electronic device that has up … transponders. 3. Satellite communications systems have become the … … and cost-effective method for moving large quantities of data over long distances. 4. The primary advantage of satellite communications is the … of area that can be covered by a single satellite. 5. Three satellites placed in … orbits can cover the entire surface of the earth, with some overlap.

 

4. Translate these sentences into your native language:

1. A satellite is a solar-powered electronic device that has up 100 transponders (a transponder is a small, specialized radio) that receive, amplify, and retransmit signals; the satellite acts as a relay station between satellite transmissions stations on the ground (called earth stations). 2. Although establishing satellite systems is costly (owing to the cost of a satellite and the problems associated with getting it into orbit above the earth’s surface and compensating for failures), satellite communications systems have become the most popular and cost-effective method for moving large quantities of data over long distances. 3. However, satellite transmission does have some problems: (a) the signals can weaken over the long distances, and weather conditions and solar activity can cause noise interference; (b) a satellite is useful for only 7 to 10 years, after which it loses its orbit; (c) anyone can listen in on satellite signals, so sensitive data must be sent in a secret, or encrypted form; (d) Depending on the satellite’s transmission frequency, microwave stations on earth can ‘jam’, or prevent, transmission by operating at the same frequency.

 

Retell the text.

Text 16







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