Unit 13

I. Выпишите из Прил. 1 значения следующих слов, запомните их:

introduce (v), reduce (v), noise (n), improve (v), quality (n), adopt (v), consider (v), considerable(a), arrange(v), shape (n).

II. Выпишите из Прил. 2 значения следующих терминов, запомните их:

limiter(n)

impulse noise

pulse-code modulation (PCM)

numerical value

III. Прочтите следующие слова, определите по суффиксу, какой частью речи они являются, переведите их:

noise(n) – noisy – noiseless; introduce – introductlon;

improve(v) –improvement; reduce – reduction;

adopt – adoption;

consider – reconsider – consideration – considerable – considerably;

arrange(v) – rearrange – arrangement;

create(v) – recreate – creation – creative – creature.

IV. Дайте русский эквивалент следующих словосочетаний:

commercial television signal, radio spectrum, newest transmission method, pulse code modulation, binary code groups, amplitude values.

V. Прочтите текст, выберите подходящее по смыслу слово из представленных в скобках, переведите текст.

No information can be communicated by radio waves (whether, without, with) modulating them. In amplitude modulation, the amplitude of the carrier wave is (charged, changed, created) according to the amplitude of the modulated (single, signal, simple). In frequency modulation, the amplitude of the carrier wave is kept constant.

Frequency modulation has two advantages over AM. It is less (effected, affected, reflected) by interference and it reproduces music more faithfully (достоверно). A VHF receiver is more complicated (then, than, when) one for amplitude modulation, but the reception is much better.

VI. Прочтите текст, разделите его на логико-смысловые единства, озаглавьте их.

MODULATION (2)

1. In the early I930s Edwin H. Armstrong introduced the idea of using frequency modulation as a way of reducing noise and improving the quality of the received radio signal. In FM the frequency rather than the amplitude of the carrier wave is modulated. In AM if the amplitude of modulation is to be increased, the power must be increased proportionally. In FM the amplitude of the frequency modulation can be increased without increasing the power at all. This is the basic difference between the two systems. In addition, since the amplitude of the FM carrier is constant, limiters can be used to reduce impulse noise.

2. АM was adopted for the transmission of the video part of the commercial television signal partly because it was considered easier to generate than an FM signal. But the main reason was that it requires considerably less space in the radio spectrum. On the other hand, the audio part of the television signal is transmitted by FM.

3. One of the newest transmission methods is the pulse code modulation (PCM). In pulse code modulation the signal consists of a rapid sequence of pulses of constant amplitude arranged in binary-code groups (sequences of O's and I's) that correspond to numerical values. The numerical values represent the amplitude values needed to recreate the shape of a signal.

(1,300)

VII. Задания к тексту. Прочтите 1, 2 абзацы текста, найдите ответы на вопросы.

Who introduced the idea of using frequency modulation? What is the difference between AM and FM? Why was AM adopted for the transmission of the video part of the commercial TV signal? What type of modulation is used to transmit the audio part of the TV signal?

Переведите текст абзацев.

Прочтите и переведите 3 абзац текста.