Учебное пособие предназначено для бакалавров всех специальностей и направлений подготовки радиотехнического факультета. В нем представлены материалы для аудиторной и самостоятельной работы
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UNIT 13Task 1.Study new words and word combinations
Task 2 .Match the pairs of synonyms.
Task 3. Complete the table with the related words and memorize them.
Task 4. Use the word in brackets to form a word which fits in the sentence. 1. Using this approach we’ll get … results (to value). 2. The a) … b)… a carrier wave (to modulate). 3. A … capacitor can vary between 5 and 65 picofarads (to vary). 4. AF stands for audio …. (to frequent). 5. The … selects the required signal (to tune). Task 5. Read the text and answers the questions. ELECTRONIC DIAGRAMS Although electronic devices may look complicated, they are made up of common basic units (“building blocks”)connected together. The function of each of these units and the path of the signals between them can be shown in a block diagram. For example, the block diagram of a simple radio is shown in Figure 1.  To understand how the radio works, it is important to understand the function of each unit than to know what components are used. This is known as a systems approach to electronics. For example, in Fig. 1 the tuner selects the required signal, the detector then separates off the audio part of the signal, and the AF amplifier (amp) amplifies it. The connections and values of the components inside these basic units can be shown in a circuit diagram using standard electronic symbols. Fig.2 shows the circuit diagram for the simple radio.  1. What do we call the two types of diagrams shown in the text? 2. What do we call the approach to electronics which focuses on the function of units? Task 6. How many of the circuit symbols in Fig.2 can you identify? Use Appendix 1 to help you. Task 7. Here are some circuit symbols. Label them and describe their function. For example: 3h It’s called a transformer. It steps AC voltages up or down.  This list of functions may help you. vary capacitance in a circuit rectify alternating current add resistance to a circuit measure very small currents break a circuit protect a circuit vary the current in a circuit step AC voltages up or down. receive RF signals measure voltages TASK 8. Study this block diagrams and circuits. Look again at Fig.1 above. We can describe it like this: The radio consists of a tuner, a detector, and an AF amplifier. is composed of Using comprise, we can start our description with the blocks: A tuner, a detector, and an AF amplifier comprise the radio. We can describe the links between each building block using these expressions: The tuner is connected to the detector. is linked to Now look again at Fig.2. We can describe the values of the components like this: R1 a-two-hundred-and-twenty-kilohm resistor C2 a hundred-picofarad (puff) capacitor Task 9. Describe the value of these components:1) R2; 2) C1; 3) R3; 4) C3; 5) P1; 6) L1. This table provides the terms you need.
Looking now at the basic units of the circuit, we can describe the volume control like this: The volume control consists of a ten-microfarad electrolytic capacitor connected in series with a five-kilohm potentiometer (pot). The positive terminal of the capacitor is connected to the output of the AF amplifier and the wiper of the pot is connected to the power amp. The third terminal of the pot is connected to the zero voltage supply rail, which is earthed. Task 10. Fill in the gaps in this description of the tuned circuit shown in Fig.2. Each gap represents one word. The circuit 1) … of a four hundred and seventy 2) … inductor which is connected in parallel with 3) … capacitor. The 4) … can be varied between five and sixty-five 5) … . The aerial is 6) … to the top end of the tuner. It is also connected to the positive terminal of the 7) … in the detector. The bottom end of the tuner is connected to earth via the zero voltage 8) … rail. Task 11. With the help of the diagram, fill in the gaps in the text. Each gap represents one word. The description should answer the questions: 1. What is the diagram of? 2. What does it consist of in terms of blocks? 3. How are the blocks connected? 4. What is the function of each block?  Fig. 3 Fig.3 shows the block diagram of an amplitude-modulated (AM) radio transmitter. It 1) … of a radio frequency (RF) oscillator, a 2) …, an audio frequency (AF) amplifier, and an RF power amplifier. The RF 3) … generates an RF 4) … wave which is fed into the modulator. The microphone converts sounds into audio frequency signals which are amplified by the AF 5) …. The modulator then uses the amplified AF 6) … to modulate the RF carrier wave. The power of the modulated carrier wave is increased by the RF 7) … amplifier. The strong modulated output signals are fed to the 8) … which enables them to be transmitted over long distances. TASK 12. Watchthevideoanddecide whether the statements below are true or false. Correct the false ones. 1. According to the video, the simplest radio comprises of more than five blocks. 2. The tutor says that there is only one method to complete the exam task. 3. The basic components include: a tuned circuit, antenna, RF filter, and a demodulator as well as your headphones. 4. Antenna is the first element as it catches the signal. 5. Antenna receives the pulses which are processed by a tuned circuit to pick out the signals to need. 6. The audio signal is separated from its carrier wave with the help of the tuned circuit. 7. The RF filter comes before the headphones. |