Radio communication

Unit 1 Radio engineering systems

1. Memorize the words:

To travel – распространяться

transmitting range – дальность передачи

a receiver – приемник

a transmitter – передатчик

a high-frequency oscillator – высокочастотный генератор колебаний

an oscillatory circuit – колебательный контур

a capacitor – конденсатор

an amplifier – усилитель

a detector – детектор, следящий механизм

a rectifier – выпрямитель, детонатор

the audio frequency – звуковая частота

to couple together – соединять, спаривать

by means of a switch – с помощью переключателя (коммутатора)

means of communication – средства связи

telegraph sending key – телеграфный ключ

dots and dashes – точки и тире

the mirror galvanometer – зеркальный гальванометр

powdered carbon – порошковый углерод

a far sensitive receiver – гораздо более чувствительный приемник

wireless communication – беспроводная связь

a transmitting / receiving coil – передающая / приемная катушка

2. Read the text and explain the operation principle of radio communication:

Radio communication

Radio communication is the transmission of high frequency energy from the transmitter to the receiver without wires. Radio is a device that transmits and receives signals and programs by electromagnetic waves. Since the process of radio communication includes transmission and reception of signals, the two necessary components of radio are a transmitter and a receiver.

The first component of radio, the transmitter, is a device producing radio-frequency energy. The transmitter consists of a high-frequency oscillator including an oscillatory circuit (a coil and a capacitor) and one or more amplifiers. Electric oscillations are produced in the antenna of the transmitter. They travel in all directions. Electron lamps are used to amplify currents and give greater transmitting range and better reception.

Radio waves are electric waves of very high frequency; they travel through space at a speed of light, and differ from other wave forms only n frequency (number of vibrations per second).

The second important component of radio communication is the receiver, a device that receives waves sent out by a transmitter. Radio receiver demodulates these waves, and they are heard as speech, music or signals. To understand this process let us consider the principle of operation of these devices.

A microphone is connected to the circuit of the transmitting antenna. When we speak into the microphone its resistance varies with the audio frequency. An alternating current is established in the microphone and antenna circuits, and its frequency is the same as the audio frequency. Oscillations of the same frequency are induced in the antenna and the oscillatory circuit of a receiver. These oscillations are in fact a high-frequency current. In order to reproduce the transmitted sound, this current modulated by audio frequency should be sent through the telephone, and a detector or rectifier should be connected to the telephone circuit. The audio frequency rectified current passes through the telephone and produces oscillations. These oscillations will reproduce the sounds produced at the transmitting station. The operation of a radio set will be the better, the more energy is received by its oscillatory circuit. The oscillatory circuit is also provided with a ground. It is important for god operation of the receiver. The antenna should be grounded by means of a switch.

Internet radio, also known as web radio or net radio is an audio broadcasting service transmitted via the Internet. Internet radio services are usually accessible from anywhere in the world. This makes it popular among listeners with interests that are not adequately served by local radio stations. Internet radio services offer news, sorts, talk and various genres of music – everything that is available on traditional radio stations.

3. Look through the text and answer the questions:

1. What is radio communication? 2. What are the main components of radio? 3. What is a transmitter? 4. What does it consist of? 5. What is used for amplifying currents? 6. What happens in the microphone when we speak into it? 7. What kind of current is established in the microphone and antennas circuit? 8. What device should be connected to the circuit in order to reproduce the transmitted sounds? 9. By what means is the antenna grounded? 10. How are transmitted sounds reproduced in the receiver?

4. Find out synonyms between:

Nouns: specialist; improvement; traffic; dot; instrument; speed; transport; operation; expert; wire; point; conversation; invention; wireless; communication; tool; state; link; power; connection; perfection; possibility; prize; oscillations; bonus; capacitors; vibrations; energy; radio; feasibility; country; rate; work; conductor; discovery; speech; condenser; device.

Verbs: to provide; to produce; to establish; to demonstrate; to induce; to amplify; to involve; to build; to improve; to receive; to lay; to link; to continue; to invent; to use; to go on; to apply; to supply; to install; to intensify; to construct; to perfect; to connect; to put; to get; to advance; to include; to move forward; to excite; to show; to generate.

Adjectives: distant; fast; important; modern; several; wonderful; various; intelligible; simple; different; quick; some; far; primitive; understandable; remarkable; present-day; significant.

5. Read the text and tell about developed communication systems: