1 Find in the text English equivalents to the following Russian words and word combinations:

Усилить сигнал, аналоговая сеть, амплитудная модуляция, канал передачи, фазовая манипуляция, уплотнение с временным разделением, низкочастотный аналоговый сигнал, шумовой порог, несущая, радиопередача, устанавливать связь, преобразовать сигнал, дискретное значение, двухточечное соединение, связь по телефонной линии.

2 Using the text give derivatives from the following words and translate them into Russian:

To communicate, to transmit, to attenuate, to repeat, to modulate, to inform, to continue, to distinguish, to route.

3 Answer the following questions:

1 What is telecommunication?

2 What does a telecommunication system consist of?

3 What is point-to-point communication?

4 What is an advantage of digital signals over analog ones?

5 What is a network?

6 What types of networks are used for transmission of information?

7 What allows distinguishing attenuation from noise?

8 What is modulation and what is it used for?

9 What keying techniques exist?

10 What modulation schemes are there?

4 Fill in the table using the information from the text:

Device	Function

5 Choose the definition that fits each word as it is used in the text:

Communication 1) the act or an instance of communicating, the imparting or exchange of information, ideas, or feelings;

2) smth. communicated, such as message, letter, or

telephone call.

Network 1) a system of interconnected computer systems,

terminals, and other equipment allowing information to be exchanged;

2) a group of broadcasting stations that all transmit the same programme simultaneously;

3) a system of interconnected components or circuits.

Noise 1) undesired or irrelevant elements in a visual image;

2) any undesired electrical disturbance in a circuit,

degrading the usual information in a signal.

Channel 1) a course into which smth. can be directed or moved;

2) a band of radiofrequencies assigned for a particular

purpose, ecially the broadcasting or a television signal;

3) a path for an electromagnetic signal.

Value 1) precise meaning or significance;

2) the particular quantity that is the result of applying

a function or operation for some given argument.

6 Fill the blanks using the words below:

receiver, transmission, network, switches, transceiver, modulation, modulated.

1 Connection between users is established by…..

2 …..is a device acting as both a transmitter and …..

3 The shaping of a signal to convey information is known as ….

4 In terminal repeater stations speech signals are …. and combined before ….

5 A collection of transmitters, receivers or transceivers that communicate with each other constitute a …

Text 2

Telephone

In an analogue telephone network, the caller is connected to the person he wants to talk to by switches at various telephone exchanges. The switches form an electrical connection between the two users and the setting of these switches is determined electronically when the caller dials the number. Once the connection is made, the caller's voice is transformed to an electrical signal using a small microphone in the caller's handset. This electrical signal is then sent through the network to the user at the other end where it transformed back into sound by a small speaker in that person's handset. There is a separate electrical connection that works in reverse, allowing the users to converse.

The fixed-line telephones in most residential homes are analogue – that is, the speaker's voice directly determines the signal's voltage. Although short-distance calls may be handled from end-to-end as analogue signals, increasingly telephone service providers are transparently converting the signals to digital for transmission before converting them back to analogue for reception. The advantage of this is that digitized voice data can travel side-by-side with data from the Internet and can be perfectly reproduced in long distance communication (as opposed to analogue signals that are inevitably impacted by noise).

Mobile phones have had a significant impact on telephone networks. Mobile phone subscriptions now outnumber fixed-line subscriptions in many markets. Increasingly these phones are being serviced by systems where the voice content is transmitted digitally such as GSM or W-CDMA with many markets choosing to depreciate analogue systems such as AMPS. There have also been changes in telephone communication. The widespread adoption of systems is based on optic fibers. The benefit of communicating with optic fibers is that they offer increase in data capacity, due to several factors: First, optic fibers are physically much smaller than competing technologies. Second, they do not suffer from crosstalk which means several hundred of them can be easily bundled together in a single cable. Lastly, improvements in multiplexing have led to an exponential growth in the data capacity of a single fiber.

EXERCISES