Task 4. Retell the text using new words.

1. Some years ago India began its Satellite Instructional Televi­sion Experiment. This experiment showed (that) satellite television programs had been a success with schoolchildren, their knowledge level had increased considerably. It was found that children could remember and speak about programs which they had seen several weekback. 2. Many experts could not decide whether so much TV was harmful to the individual's health and mental activity or not. 3. Specialists did not know if it was possible to continue mod­ernizing the electronic equipment of this kind — the costs were too high. 4. There appeared some reports that we had technical means to use much more channels on a TV set and we should be able to see many sports and news programs from all parts of the world soon. 5. At first it was not clear whether new telephone and teletype communication with ships via six satellites was economical and re­liable or not. 6. It was announced that the cryogenic cable had been invented in Russia. 7. We read that for the first time electricity had been applied for industrial use in silver workshops in Paris. 8. We know different transmitters are used in a television system — one for the sound channel and the other for the picture channel. 9. We learnt from the lecture that electricity was still considered the main source for new technological developments.

Методические рекомендации:

Студентам следует прочитать текст очень внимательно, затем готовиться к

занятиям в определенной последовательности. Подготовится к устному

сообщению по теме.

Рекомендуемая литература:

4 (осн.) стр 588-589

Контрольные вопросы

1. When did the first TV set appear?

2.Were people interested in the new invention?

3. Why was the TV production stopped in 1940?

4. What is cable television?

5. What is digital television?

6. What is high-definition television?

Практическое занятие № 13

Тема: Telecommunication

Task 1.Read the text: Television System

The television transmitter sends out special signals. They are sent out in addition to the picture impulses. The signals synchronize the picture at the receiver with the picture picked up by the camera.

At the television receiver, the picture and audio sig­nals are picked up simultaneously by a single antenna;

The voltages induced in the receiving antenna are fed into the radio frequency stage of the receiver; and the picture carrier and the sound carrier are converted by super heterodyne conversion method into two separate intermediate frequency signals. One signal corresponds to the sound carrier and the other — to the video or picture carrier. Two separate intermediate frequency amplifier channels are employed; one for the picture signal and the other for the sound signal. The sound intermediate frequency signal is demodulated by a detector. After proper ampli­fication by the audio amplifier, the sound signal is repro­duced by the loud speaker in the usual way.

The picture intermediate frequency signal is amplified by several stages having wide-band frequency character­istics and is then fed into the video (picture) detector, where the intermediate frequency signal is then demod­ulated. The video (picture) signal which appears in the output of the detector is then amplified in the video amplifier, which corresponds to the audio amplifier in the sound receiver. Only it must pass a much wider range of frequencies.

Vocabulary:

single – единый, один

loud speaker – громкоговоритель

to feed – питать usual – обычный

intermediate – промежуточный several – несколько

to correspond – соответствовать stage – каскад, ступень

bend – полоса

Task 2. Read and translate the following words without a dictionary:

synchronize, characteristics, special, modulate, demodulate, detector, reproduce, camera, voltage

Task 3. Read and translate the following word combinations:

radio frequency stage; detector output; separate inter­mediate frequency signals; separate intermediate frequen­cy amplifier channels

Task 4. Compare the meanings of these word combinations:

super heterodyne conversion method — conversion meth­od; frequency signal — sound intermediate frequency signal; wide band — wide-band frequency characteris­tics

Task 5. Read and translate the questions. Find answers to the questions in the text:

1. What kind of signals are picked up simultaneously by a single antenna?

2. What kind of carriers are converted by super heterodyne conversion method?

3. How many stages amplify the picture intermediate frequency signal?

4. What part of the television transmitter amplifies the video signal?

Дата добавления: 2015-11-14