ĐIỆN tử VIỄN THÔNG DTVT2 nhóm7 bai6 txt khotailieu

Nhóm 7 Nguyễn Bá Duy Nguyễn Khắc Ngân Trần Minh Đức Vũ Văn Chinh Dương Văn Hùng Đỗ Văn Sang Task 1: Television x-rays machine microwave oven telephone aerial Task 2: Surface wave Frequen

Nhóm 7 Nguyễn Bá Duy Nguyễn Khắc Ngân Trần Minh Đức

Vũ Văn Chinh Dương Văn Hùng

Đỗ Văn Sang

Task 1:

Television

x-rays machine

microwave oven

telephone

aerial

Task 2:

Surface wave Frequencies low Frequencies

Travels along the ground, flowing the curvature of the earth’s

surface Range the range is about 1500km at low Frequencies

Difficulties energy is absorbed from it by the ground

Task 3:

Sky wave Space wave Frequencies High frequencies Very high or ultra high

frequencies Travels Bounces back to the

ionosphere where it is again gradually refracted and return earthwards

Giving line of sight transmission

Range Around the earth if it

enough energy

A range of up to 150km is possible on earth

Difficulties the critical frequency

varies with the time of day and the seasons

can be hampered by hills, tall buildings, trees

Task 4:

1-a transmitting aerial

2-e surface wave

3-d space wave

4-c sky wave

5-b receiving aerial

Task 5

1 When the switch is closed ,current flows through the primary of the

transformer

2 When the radar signal strikes a plane It is reflected

3 on discharging quickly, a cell may become hot

4 When the TV receives signals from the remote control, it follows your instructions

5 When the radar receiver receives the reflected signal, the signal is compared with the transmitted signal

6 On choosing a course in electronics, you think carefully about your future

7 When microwave signals strike a high building, they are deflected

8 On making a recording, you should ensure the recording levels are

satisfactory

9 On 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)

communicate communicator communication

Task 9:

1 AF - audio frequency

2 RF - radio frequency

3 AM – amplitude modulated

4 FM – frequency modulated

Task 10:

1 FM carrier - d

2 AM carrier - c

3 AF signal - b

4 RF carrier - a

Task 11:

1 aerial

2 RF tuner

3 RF amplifier

4 detector

5 AF amplifier

Receives weak RF signals

tuned to the required radio frequency and selected RF waves passed on to the RF amplifier

convert a low-power radio-frequency signal into a larger signal of significant power

recovers information contained in

a modulated radio wave

amplifies low-power audio signals

to a level suitable for driving loudspeakers

6 loudspeaker Converts the audio signal into

sound