ĐIỆN tử VIỄN THÔNG DTVT2 nhom1 bai6 khotailieu

NHÓM 1 – LỚP Đ8-ĐTVT 2
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LƯƠNG NGỌC LONG
HOÀNG NGỌC TRUNG
HOÀNG THỊ LINH
NGÔ ANH TUẤN
PHÙNG THỊ QUỲNH
PHẠM TRỌNG HOAN

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Lesson 6: Radio
Task 1:
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Light bulb
Televison
Oven
Telephone
Heater

Task 2:
Table 1

Surface wave

Frequencies

Low frequencies.

Travels

Along the ground, following the curvature of the earth’s
surface.

Range

1500km at low frequencies (long waves).

Difficulties

It’s limited mainly by the extent to which energy is absorbed
from it by the ground.

Task 3:
Table 2:


Sky wave

Space wave

Frequencies Typically 30 MHz

VHF, UHF

Travels

Skyward

Line of sight

Range

About 80 km above the earth
to 500 km

Up to 150 km

Difficulties

The critical frequencies varies
with the time of day and the
seasons

Intervening obstacles such as
hills, buildings, or trees

Task 4:
12345-

a: transmitting aerial
e: surface wave
d: space wave
c: sky wave
b: receiving aerial

Task 5:
1. When the switch is closed, current flows through the primary of the
transformer.
2. On trisking a plane, the radar signal is reflected.
3. On discharging quickly, a cell may become hot.
4. When reciving signal from the remote control, the TV follows your
instructions
5. When the radar receiver receives the reflected signal, the signal is compared
with the transmitted signal.
6. When choosing a coures in the electronics, you think carefully about your
future.
7. On striking a hight building, microwave signals are deflected.
8. When making a recording, you should ensure the recording levels are
satisfactory.
9. When detecting an intruder, the alarm triggers an audible warning.
10. When the remote control button is pressed, the television set changes
channel.


Task 7:

Verb

Noun (component)

Noun (property)

Absorb

Absorber

Absorbion

Attenuate

Attenuator

Attenuation

Communicate

Communicator

Communication

Conduct

Condution

Conductivity

Induct

Inductor

Induction

Modulate

Modulator

Modulation

Reflect

Reflector

Reflection

Resist

Resistor

Resistance

Task 9:
1. AF : audio frequency
2. RF : Radio frequency
3. AM : Amplitude modulated
4. FM : Frequency modulated
5.
Task 10:
1234-

D: FM carrier
C: AM carrier
B: AF signal
A: RF carrier

Task 11 :
Component

Function

Aerial

Receives weak signals

RF tuner

Selects the required RF wave

RF amplifier

Amplifies the RF wave


Detector

Separates the audio modulation from the
RF carrier wave

AF amplifier

Amplifies the audio signal

Loudspeaker

Converts the audio signal into sound

Task 12 :
- Firstly , the aerial receives weak signal . Next , the RF tuner selects the
required RF wave from the aerial . Following that , the selected RF wave is
amplified by the RF amplifier and then passed to the detector , which
separates the audio modulation from the RF carrier wave . After that , the
audio frequency amplifier amplifies the audio signal to make it strong
enough to drive the loudspeaker. Finally , the loudspeaker converts the audio
signal into sound .
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