- •U n I t 1 telecommunications
- •1 Read and memorize the following words and word-combinations:
- •2 Translate the following word-combinations into English:
- •Telecommunication
- •1 Find in the text English equivalents to the following Russian words and word combinations:
- •6 Fill the blanks using the words below:
- •Telephone
- •1 Using the text give derivatives from the following words and translate them into Russian:
- •2 Fill the blanks using the words below:
- •3 Answer the following questions:
- •4 Translate the following sentences from English into Russian:
- •5 Read the text, describe the principal of telephone communication
- •Radio communications
- •1 Answer the following questions:
- •3 Choose from part II the appropriate continuation of the sentences.
- •4 Translate without using a dictionary.
- •5 Look at the following short descriptions of processes:
- •1 Using the information from the first three texts translate the following one from Russian into English.
- •U n I t 2 modulation
- •1 Read and memorize the following words and word-combinations:
- •2 Translate the following word-combinations into English:
- •Modulation
- •1 Answer the following questions:
- •2 Reply to the following sentences with a suitable question:
- •3 Translate the following fragment into English using the information from the text.
- •4 Make up a summary of the text using the cliché:
- •Digital and analog modulation methods
- •1 What do the following abbreviations stand for?
- •2 Translate the following sentences into English:
- •3 Choose from part II the appropriate continuation of the sentences.
- •4 Read the following paragraph. Fill in each blank with a suitable word given below.
- •5 Translate without using a dictionary
- •6 Make a brief summary of the text.
- •Modulator and demodulator
- •1 Translate the following word-combinations into Russian:
- •2 Answer the following questions:
- •3 Read the following paragraph. Fill in each blank with a suitable word given below.
- •4 Translate without using a dictionary.
- •1 Using the information from the first three texts translate the following one from Russian into English.
- •Модуляция и помехоустойчивое кодирование
- •U n I t 3
- •1 Read and memorize the following words and word-combinations:
- •2 Translate the following word-combinations into English:
- •Transmission systems
- •1 Answer the following questions:
- •2 Complete the following simple process description of the function of a terminal repeater station:
- •3 Complete the following tree diagram:
- •4 Read the following paragraph. Fill in each blank with a suitable word given below.
- •Why optical fibers are useful and how they work
- •1 Below are the advantages of optical fibers. Match them with an appropriate explanation:
- •2 Discuss the importance of the above advantages in using optical fiber in public telephone networks. Try to rank the above advantages in order of importance.
- •3 Complete the following tables:
- •4 Read the following paragraph. Fill in each blank with a suitable word given below.
- •5 Reply to the following sentences with a suitable question:
- •6 Make a brief summary of the text.
- •1 Answer the following questions:
- •2 Read the following paragraph. Fill in each blank with a suitable word given below.
- •3 Translate the following sentences into English:
- •1 Using the information from the first three texts translate the following one from Russian into English.
- •Оптоволокно
- •U n I t 4
- •1 Read and memorize the following words and word-combinations:
- •2 Translate the following word-combinations into English:
- •Telephone exchanges
- •1 Answer the following questions:
- •2 Complete the following table: Main characteristics of the systems
- •3 Choose from part II the appropriate continuation of the sentences.
- •4 Put the verb in brackets into the correct tense.
- •5 Read the following paragraph. Fill in each blank with a suitable word given below.
- •6 Make up a summary of the text using the cliché:
- •Switching technologies
- •1 Integrated Digital Transmission and Switching
- •1 Complete the following table:
- •3 What are the advantages of using (large-scale) integrated circuits in an exchange?
- •4 Match the following terms with a suitable explanation:
- •5 Translate the following sentences into Russian:
- •Public Data Networks
- •1 Answer the following questions:
- •2 Match the facilities with the appropriate description:
- •3 Discuss in what situations and for which user groups the above facilities would be useful.
- •1 Using the information from the first three texts translate the following one from English into Russian.
- •Digital switches
- •Оглавление
- •Английский язык
- •246653, Г. Гомель, ул. Кирова, 34.
- •Английский язык
- •246653, Г. Гомель, ул. Кирова, 34.
3 Discuss in what situations and for which user groups the above facilities would be useful.
1 Using the information from the first three texts translate the following one from English into Russian.
Text 4
Digital switches
Digital switches work by connecting two or more digital circuits together, according to a dialed telephone number. Calls are setup between switches using the Signaling System 7 protocol, or one of its variants. In U.S. and military telecommunication, a digital switch is a switch that performs time division switching of digitized signals. This was first done in a few small and little used systems. With few exceptions, most switches built since the 1980s are digital, so for practical purposes this is a distinction without a difference.
Digital switches encode the speech going on, in 8000 time slices per second. At each time slice, a digital PCM representation of the tone is made. The digits are then sent to the receiving end of the line, where the reverse process occurs, to produce the sound for the receiving phone. In other words, when you use a telephone, you are generally having your voice "encoded" and then reconstructed for the person on the other end. Your voice is delayed in the process by a small fraction of one second – it is not "live", it is reconstructed – delayed only minutely. Individual local loop telephone lines are connected to a remote concentrator. In many cases, the concentrator is co-located in the same building as the switch. The interface between concentrators and telephone switches has been standardized by ETSI as the V5 protocol.
Some telephone switches do not have concentrators directly connected to them, but rather are used to connect calls between other telephone switches. These complex machine (or series of them) in a central exchange building are referred to as "carrier-level" switches or tandems.
Some telephone exchange buildings in small towns now house only remote or satellite switches, and are homed upon a "parent" switch, usually several kilometers away. The remote switch is dependent on the parent switch for routing and number plan information. Unlike a digital loop carrier, a remote switch can route calls between local phones itself, without using trunks to the parent switch.
Telephone switches are usually owned and operated by a telephone service provider or carrier and located in their premises, but sometimes individual businesses or private commercial buildings will house their own switch, called a PBX, or Private Branch Exchange.
DISCUSSION
Choose one of the following for discussion:
1 Discuss the present state of the national network in your country (exchanges, equipment).
2 What problems for the developing countries do you foresee in installing digital exchanges in place of old, mechanical switching centers?
3 What future do you think operator personnel have in either public exchanges or private branch exchanges?
4 Why are digital time division switching systems generally considered to be the most suitable for networks of the future?