Главная | Обратная связь | Поможем написать вашу работу!
МегаЛекции

Brief history of the radio




 

Early radios run the entire power of the transmitter through a carbon microphone. While some early radios ______ 1some type of amplification through electric current or battery, until the mid 1920s the most common type of receiver ______2 the crystal set. In the 1920s, amplifying vacuum tube radio receivers and transmitters ______3 into use.

(use, be, ran, come)

One of the first developments in the early 20th century (1900-1959) ______4 that aircraft _______5 commercial AM radio stations for navigation. This ______6 until the early 1960s when VOR systems finally ______7 widespread (though AM stations are still marked on U.S. aviation charts).

(use, be, become, continue)

In 1960, Sony ______8 its first transistorized radio, small enough to fit in a vest pocket, and able to be powered by a small battery. It ______9 durable, because there ______ 10 no tubes to burn out. Over the next 20 years, transistors ________11 tubes almost completely except for very high-power uses.

(be, introduce, replace, be)

 

In 1963 color television commercially ______12, and the first (radio) communication satellite, TELSTAR,_______13. In the late 1960s, the U.S. long-distance telephone network _________14 to a digital network, employing digital radios for many of its links. In the 1970s, LORAN _______15 the premier radio navigation system. Soon, the U.S. Navy _______16. with satellite navigation, culminating in the invention and launch of the GPS constellation in 1987. Digital transmissions ________17 to be applied to broadcasting in the late 1990s.

(Begin, be converted, become, be transmitted, experiment, be launched)

EXERCISE 7

T 7

Translate the following text into English.

 

Электромагнитное излучение распространяется благодаря колебаниям электромагнитного поля, которое образуется как в воздушном пространстве, так и в вакууме. Для этого излучению не нужна особая проводящая среда (как, например, эфир). Когда радио волны проходят через проводник, колебания электрического или магнитного поля индуцируют в нем переменный ток. Он преобразуется в аудио- или другие сигналы, несущие информацию. Слово «радио» поясняет этот процесс. Телевизионные и радиопередачи, передача информации с помощью сотовой связи являются радиочастотными излучениями.

 

EXERCISE 8

 

Перескажите текст, используя выученный вокабуляр, расскажите о радио, используя информацию из изученных текстов этой части

 

 

EXERCISE 9

Look through the words below and practice in pronunciation. Read and translate the text about uses of radio

 

 

Words to be remembered:

 

feasible – реальный, осуществимый

broadcasting – широковещательный

point-to-point broadcasting – частный радиоканал, передача от точки к точке

relay – трансляция

narrowband – узкополосный канал

to near - приближаться

omnidirectional – всенаправленный

microgravity environment – состояние невесомости

interstellar probe- космическая научно-исследовательская станция

autarkic – самостоятельный, автономный

AM – amplitude modulation – амплитудная модуляция

VHF – very high frequency – очень высокая частота

vestigial sideband – частично подавленная боковая полоса

cell site – узел сотовой связи

sound carrier – звуконоситель

diathermy equipment – оборудование для диатермии

to exert – приводить в движение

Uses of radio

 

Today, radio takes many forms, including wireless networks, mobile communications of all types, as well as radio broadcasting.

Before the advent of television, commercial radio broadcasts included not only news and music, but dramas, comedies, variety shows, and many other forms of entertainment. Radio was unique among dramatic presentation that it used only sound.

Aviation voice radios use VHF AM. Aircraft fly high enough that their transmitters can be received hundreds of miles away, even though they are using VHF.

Marine voice radios can use AM in the shortwave High Frequency—3 MHz to 30 MHz. Government, police, fire and commercial voice services use narrowband FM on special frequencies. Civil and military HF (high frequency) voice services use shortwave radio to contact ships at sea, aircraft and isolated settlements.

Mobile phones transmit to a local cell site that ultimately connects to the public switched telephone network through an optic fiber or microwave radio and other network elements. When the mobile phone nears the edge of the cell site's radio coverage area, the central computer switches the phone to a new cell. Cell phones originally used FM, but now most use various digital modulation schemes. Satellite phones come in two types: INMARSAT and Iridium. Both types provide world-wide coverage. INMARSAT uses geosynchronous satellites, with aimed high-gain antennas on the vehicles. Iridium uses 66 Low Earth Orbit satellites as the cells.

Television sends the picture as AM and the sound as FM, with the sound carrier at fixed frequency (4.5 MHz in the NTSC system) away from the video carrier. Analog television also uses a vestigial sideband on the video carrier to reduce the bandwidth required.

Radio-frequency energy can be used for heating of objects. Microwave ovens use intense radio waves to heat food. Diathermy equipment is used in surgery for sealing of blood vessels. Induction furnaces are used for melting metal for casting.

Tractor beams can use radio waves which exert small electrostatic and magnetic forces. These are enough to perform station-keeping in microgravity environments.

Radiation pressure from intense radio waves has been proposed as a propulsion method for an interstellar probe called Starwisp. Since the waves are long, the probe could be a very light metal mesh, and thus achieve higher accelerations than if it were a solar sail.

Radio remote control use radio waves to transmit control data to a remote object as in some early forms of guided missile, some early TV remotes and a range of model boats, cars and airplanes. Large industrial remote-controlled equipment such as cranes and switching locomotives now usually use digital radio techniques to ensure safety and reliability.

Energy autarkic radio technology consists of a small radio transmitter powered by environmental energy (push of a button, temperature differences, light, vibrations, etc.). This technology includes, for example, solar power stations in orbit beaming energy down to terrestrial users.

 

EXERCISE 10

Find in the text suitable nouns for adjectives given below and translate word combinations

 

Wireless, mobile, unique, optic, shortwave, geosynchronous, high-gain, vestigial, intense, electrostatic and magnetic, interstellar, solar, remote, autarkic, environmental, terrestrial.

 

EXERCISE 11

Make up word combinations which have the construction ‘noun + noun’. Find in the text another element to each noun below and translate the expression. There could be more then one noun added.

 

 

Radio broadcasting, …services, … network, … area, …sight, …carrier, …energy, …equipment, …vessels, … furnaces, …beams, …environment, …pressure, … method, …sail, …differences, …boat, …mesh, …station

 

EXERCISE12

Answer the questions. Add information from the text to your answer

 

 

1. What forms does radio take nowadays? (wireless networks, mobile communications, radio broadcasting)

2. What kind of amplitude modulation do aviation voice radios use? (VHF AM)

3. What services use narrowband FM on special frequencies? (Government, police, fire and commercial voice services)

4. What types do satellite phones come in? (INMARSAT and Iridium)

5. What is the radio frequency energy used for? (for heating objects)

6. What was proposed as propulsion method for an interstellar probe? (Radiation pressure from intense radio waves)

7. What does energy autarkic radio technology consist of? (a small radio transmitter).

 

 

EXERCISE 13

Make a sentence out of the two parts from the table

 

 

1. Radio was unique amongdramatic presentation
  1. in the shortwave High Frequency
  1. Aircraft fly high enough that their transmitters
  1. that it used only sound.
  1. Marine voice radios can use AM
  1. now usually use digital radio techniques to ensure safety and reliability.
  1. Electrostatic and magnetic forces of radio waves
  1. can be received hundreds of miles away
  1. Radiation pressure from intense radio waves has been proposed
  1. solar power stations in orbit beaming energy down to terrestrial users.
  1. Large industrial remote-controlled equipment such as cranes and switching locomotives
  1. are enough to perform station-keeping in microgravity environments.
  1. Energy autarkic radio technology includes
  1. as a propulsion method for an interstellar probe called Starwisp.

 

EXERCISE 14

What significance do the following names have in relation to the text‘Uses of radio’? Look at the example:

 

Radio broadcast – Before the advent of television, commercial radio broadcasts included news and music, dramas, comedies, variety shows, and many other forms of entertainment.

1) VHF AM

2) 3 MHz to 30 MHz.

3) narrowband FM

4) INMARSAT and Iridium

5) geosynchronous satellites

6) 66 Low Earth Orbit satellites

7) 4.5 MHz in the NTSC system

8) a vestigial sideband

9) heating of objects

10) microgravity environments

11) radiation pressure

12) radio remote control

13) energy autarkic radio technology

14) Starwisp

UNIT IV

 

Frequency converters

EXERCISE EXERCISE EXERCISE EXERCISE EXERCISE 1 EXERCISE EXERCISE

Before reading the text answer questions:

· What branch of technology are frequency converters connected to?

· What role do they play?

· In what devices are they used?

Поделиться:





Воспользуйтесь поиском по сайту:



©2015 - 2024 megalektsii.ru Все авторские права принадлежат авторам лекционных материалов. Обратная связь с нами...