Unit 11

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

message (n), grow (grew, grown) (v), strength (n), decrease (v), represent (v), broadcast (v), pattern (n), extent (n), replace (v).

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

sender (n) aerial (n)

receiver (n) earphones (n)

dot (n) continuous waves

dash (n) key (n)

buzz (v) headphones (n)

buzzer (n) loudspeaker (n)

III. Назовите глаголы, от которых образованы следующие существительные, переведите их:

transmission, connector, detection, production, inventor, discovery, sender, growth, development, modulation, separation, reception, receiver, amplification, reproduction, replacement, representation.

IV. Прочтите и переведите следующие словосочетания:

low frequency currents, higher frequency currents, sound waves, radio wave.

V. Прочтите текст, обращая внимание на первые предложения абзацев.

Перечислите основные положения текста.

RADIO COMMUNICATION

1.The transmission of messages through space without wires connecting the sender and the receiver, as they do in telegraph and telephone, grew out of electromagnetic theories put forward by James Сlerc-Мaxwell in about 1865. Some twenty years later Heinrich Hertz, in Germany, detected and produced electromagnetic (radio) waves for the first time. New methods of detecting radio waves were invented in England, France and Russia, but the first practical use of the discovery was made by an Italian, Guglielmo Marconi. In 1901 he sent a message nearly 3,500 km across the Atlantic Ocean.

2. These early messages were sent in Morse code, a system of short and long signals invented by Samuel Morse. Each letter of the alphabet is represented by its own combination of dots and dashes. The radio waves were sent out in groups of short and long signals which operated a buzzer at the receiving end. The buzzes had to be decoded before the message could be read.

3. Wireless waves could not carry speech until a method had been developed for combining the low frequency (audio frequency) currents produced in a microphone by sound waves with the much higher-frequency currents that produce radio waves. This only became possible after the invention of the thermionic valve. The valve can be used as an oscillator to produce the high-frequency currents that produce radio waves: these high-frequency currents are then modulated (increased or decreased in amplitude) by the currents produced by sound waves in the microphone. The modulated current is fed to the transmitting aerial and the radio waves are broadcast into space. They are received by the receiving aerial and the pattern of the sound wave is separated from the radio wave by another valve (detector). The audio-frequency current is then amplified to increase its strength, and finally the original sound waves are reproduced by a loudspeaker or earphones. Thermionic valves have now been replaced to a great extent by transistors.

(1,800)

VI. В следующих предложениях замените глагол-сказуемое в действительном залоге сказуемым в страдательном залоге, изменив соответственно порядок слов в предложении.

Образец:

A loudspeaker reproduces (reproduced) the original sound waves. The original sound waves are (were) reproduced by a loudspeaker.

1. Fig. 1 illustrates the basic elements of a radio communication system. A radio transmitter generates the r. f. waves. A microphone controls radio waves. A transmitting antenna radiates the waves. A radio receiver selects and amplifies the transmitter signal. A loudspeaker converts the demodulated electrical waves into sound.

2. Morse invented a system of short and long signals called Morse code. In this system a combination of dots and dashes represented each letter of the alphabet.