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7/29/2019 Ch 16 Communication St
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SES 1511 Kelantan 2007 *The bolded and italic letter is the answer 306
Radio
Communication
CHAPTER 16 ELECTRONICS AND INFORMATION AND
COMUNICATION TECHNOLOGY (ICT)
Electronic component
Function
Radio transmission systemFunction
Radio receiver systemFunction
Radio wave
Characteristics
Location
Electronic and Informationand Communication
System
Information transmissionTechnology
Satellite communicationsystem
Development
1. RADIO WAVE
UsesHow itworks
Uses
The Characteristics of Waves
Displacement(cm)
Peak / Crest
Amplitude
Distance (cm)
Wave length
Trough
A wave is produced from the vibration or oscillation of any systems. The wave carries the energy from the wave source outwards to the surrounding areas. There are two types of wave:
i) Mechanical wave needs medium to travel.
ii) Electromagnetic wave could travel through vacuum. Wave amplitude :
- Maximum displacement of particles from their rest position.
- Amplitude represents the energy level of a wave.
- Amplitude is measured in meter (m).
- The symbol for amplitude is A The wave frequency is the number of complete waves formed in one second. The symbol is f
and the SI unit is Hertz (Hz).
The wave length is the distance between two successive points which are in the same phase.
The symbol is and the SI unit is meter (m)
The wave velocity is the distance traveled by a wave in one second.
The symbol is v and the unit is meter per second (m s-1)
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Wave velocity (v) = frequency (f) x wave length ()
Radio wave in communication
Characteristics of radio wave
1. A kind of electromagnetic wave that could travel through vacuum.2. Could be reflected, refracted and diffracted.
3. Travels very fast because it travels with the velocity of light i.e 3 x 108
m s-1.
4. Could carry all information needed for radios, televisions and mobile phones to createsound and pictures.
Electromagnetic wave spectrum
Lowestfrequency
FREQUENCY INCREASE Highestfrequency
Radiowave
Microwave
Infrared
Visiblelight
Ultraviolet
X-ray Gammaray
Longest
wavelengthShortest
WAVELENGTH INCREASE wavelength
Uses of radio wave
1. radio and television broadcasts2. telecommunications e.g sending telephone signals3. weather forecasting4. space studies
5. satellite photography
Types of waves in communication1. Low radio frequency wave for local communication, earth wave and covers the
distance of 100 km.2. High radio frequency wave could be reflected by ionosphere, sky wave and
longer distance traveled.3. Microwave space wave and used for satellite communication.
2. RADIO COMMUNICATION SYSTEM
Electronic component
Name ofcomponents
Symbols Function
Resistor Controls the magnitude of the current in thecircuit.
Capacitor Variable capacitor
Fixed capacitor
Store charges and electrical energy.
Allow alternating current to pass through but notthe direct current.
Channel the flow of radio frequency carrier waveinto the earth to eliminate the unwanted radiosignals.
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Inductor Store energy in the magnetic field.
Allow direct current to flow through but not thealternating current.
Work with the variable capacitor to form a tuning
circuit.
Diode Allow the current to flow in one direction.
Act as rectifier to separate the audio frequencysignals from radio frequency signals throughdemodulation.
Transistor
p-n-p
n-p-n
Amplify audio frequency signals before sendingthem to the loudspeaker or earphones.
Transformer Changes (increases or decreases) the voltage of analternating current.
RADIO TRANSMISSION SYSTEM
Creates radio wave Radiofrequencyoscillator
Microphone
Amplify (increase theamplitude) of audio
frequency wave
Amplifier aerial
Amplifier Modulator Amplifier
Convert sound wavesinto electrical signals
(audio frequencysignals )
Amplify (increase theamplitude) of audio
frequency wave
Combine the audiofrequency wave with
radio waves.
Amplify (increase theamplitude) of audio
frequency wave
Sound and pictures are converted into electrical signals Electrical signals carry sound audio signalsElectrical signals carry image video signals
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Two ways of modulation:
Radio wave Radio wave
+ +
Audio frequency wave Audio frequency wave
AM wave(Amplitude modulation)
The amplitude of radio wave changesaccording to the amplitude of radio wave
FM wave(Frequency modulation)
The frequency of radio wave changesaccording to the frequency of radio
wave
RADIO RECEIVER SYSTEM
Aerial/Antenna
Receives variousmodulated radio wavesfrom various
transmission station
Tuner
Composed of variablecapacitor and inductor.
Variable capacitor could be
Composed of diodeand capacitor to
separate audio wave
from radio wave(Demodulation)
Detector/Demodulator
Amplifier
Increasethe audiosignals
Loudspeakerchanges audio
adjusted until the frequency issimilar to the frequency of the
selected radio wave
signals intosound waves
Transmitting and receiving signals in radio communication system.
Radio wave is used as carrier wave to carry various information. Radio waves have amplitude and specific frequency. Radio waves carry audio and video signals.
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The process of transmitting information signals by Amplitude Modulated (AM) Radio Waves
AM radio wave
Radio frequency
signals AM signals
Oscillator Modulator Amplifier
Audio signals
Soundwave
Microphone
The process of receiving information signals in the form of Amplitude Modulated (AM) Radio
Waves
Radio wave
Similar form ofelectrical signal
Audio signal
Tuner Detector Amplifier
Amplifiedaudio signal
Sound wave
3. DEVELOPMENT OF INFORMATION AND COMMUNICATION TECHNOLOGY
Communication satellite Satellites orbit the earth with the direction andvelocity similar to earth.
Intelsat 1 aboveAtlantic Ocean
Earth Intelsat IIIaboveIndianOcean
Malaysia communicates with other countries inthe world through three Intelsat satellites.
MEASAT satellite was launched to let Malaysiacommunicates with East Asia countries.
Intelsat II abovePacific Ocean
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PAPER 1
1. Which of the following is example of mechanical wave?
A. Sound wave
B. Light waveC. Radio waveD. Microwave
2. . The diagram shows a wave form.
Y
X
What are X and Y ?
X Y
A Crest Amplitude
B Wavelength Trough
C Amplitude Wavelength
D Trough Crest
3. The diagram shows a wave form.
Distance
Which of the following represents the wavelength of the wave?
A. PRB. PSC. PTD. PV
4. The diagram shows a wave form.
0.5 1.0
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If the wave has a wavelength 10 mm, what is the speed of the wave?( Velocity, v = f )
A. 2 mms-1
B. 5 mms-1
C. 10 mms-1D. 20 mms-1
5. The diagram shows the electromagnetic spectrum.Lower Higher
FrequencyInfrared P Ultraviolet X-ray Q
What are P and Q ?
P Q
A. Visible light Gamma rayB. Microwaves Visible light
C. Microwaves Gamma ray
D. Short waves microwaves
6. An organ produces a note of 512 Hz. What is the wavelength of the sound waveproduced?Speed of sound in air = 330 ms-1Velocity, v = f
A. 0.64 mB. 1.55 mC. 155 mD. 182 m
7. Which of the following is the amplitude of the wave?
AD
B
C
8. Which of the following statements is true about ultra high frequency?
A. Reflected by ionosphere and is used for radio AMB. Not reflected by ionosphere and is used for radioAM
C. Not reflected by ionosphere and is used for mobile phoneD. Reflected by ionosphere and is used for mobile phone
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9. Which of the following waves are most suitable for sending radio communicationinter country?
A. Long waveB. Short waveC. Audio waveD. Medium wave
10. Which is the symbol for a transistor?
A. C.
B. D.
11. If a student wants to find THR radio station, he turns the tuner dial.Which part of electronic components involve?
A. DiodeB. ResistorC. InductorD. Variable capacitor
12. Acts as an electrical valve that allows current to flow in one direction.Which of the following electronic components allows current to flow in one direction?
A. DiodeB. InductorC. Resistor
D. Transformers.
13. Which of the following is true about an electronic component and itssymbol?
Electronic Component Symbol
A. Diode
B. Resistor
C. Capacitor
D. Inductor
14. Which of the following statements is true about transistor?
A. Acts as electrical valveB. Acts as a current amplifierC. Stores electric charges and discharge.D. Used to regulate voltage of electrical power supply
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15. The sound signal must be combined with carrier wave before they are transmitted.What is the process?
A. ReflectionB. DiffractionC. ModulationD. Amplification
16. Which of the following wave patterns is frequency modulation?
A. C.
B. D.
17. The diagram shows a simple radio receiver system.
Radio waves
Antenna
Tuner Demodulator
Speaker
P
What is the function of P?
A. To amplify audio signalsB. To generate high radio frequency waveC. To change audio signals to radio wavesD. To separate audio signals from radio waves
18. The diagram shows communication satellites.
Which of the following statements are true?
A. Each satellite receives and transmits a signal.B. These satellites are used for Asian Country onlyC. These satellites are used for TV communication onlyD. The satellites are remain at the same place on earths surface
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19. The diagram shows the transmission process of AM signal in radiocommunication system.
Oscillator S Amplifier
Microphone
What is the function of S ?
A. To generate radio frequencyB. To amplify the signals of radio wave
C. To transmit the signals of radio waveD. To combine the radio frequency with the audio frequency.
20. Which of the following electronic components is used to increase or decrease the a.cvoltage?
A. C.
B. D.
21. Which of the following is the function of an inductor ?
A. Store electronsB. Resists the flow of currentC. Permist the flow of current in only one direction.D. Produces electric field when current flows through it
22. A sound wave with a wavelength 2.0 m travels in the air.What is the frequency of the wave?(velocity of sound wave in air = 330 m s-1)
A. 1/330 HzB. 165 HzC. 330 HzD. 660 Hz
23. What electronic component causes carrier wave to be earthed?
A. DiodeB. Resistor
C. TransistorD. Capacitor
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SES 1511 Kelantan 2007 *The bolded and italic letter is the answer 316
24. The diagram shows a wave form.
Time/s
0s 0.2s 0.4s 0.6s 0.8s 1.0 s
What is the frequency of the wave?
A. 0.2 HzB. 1 Hz
C. 5 HzD. 10 Hz
25. Which of the following is arranged in order of increasing wavelength ?
A. Radio wave, visible light, X-rayB. Infrared, gamma ray, visible lightC. X-ray, radio wave, ultraviolet lightD. Gamma ray, visible light, Microwave
26. How many satellites are used to transmit signals to all parts of the world?
A. TwoB. ThreeC. FourD. Five
27. The diagram shows a simple radio receiver system.
What is X?
A. DiodeB. AerialC. TransistorD. Rheostat
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28. Which of the electronic components in a simple radio receiver functionsto change audio signal to sound?
A. DiodeB. AerialC. SpeakerD. Transistor
29. Which of the following satellites has been launched by Malaysian government?
A. Measat C. IntelsatB. Asiasat D. Apstar
30. What is the time taken for communication satellites to make a complete orbitaround earth ?
A. 6 hours C. 24 hours
B. 12 hours D. 48 hours
31. The following information shows the characteristics of waves.
P Amplitude Q Frequency RWavelengthS Velocity of transmission
Which characteristics can be measured directly using an oscilloscope?
A. P and Q
B. R and SC. Q and SD. P, Q, R and S.
32. The diagram shows a process in radio transmission system.
Carrier
wave Process Y
Audio
signal
What is process Y?
A. TuningB. ModulationC. AmplificationD. Demodulation
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SES 1511 Kelantan 2007 *The bolded and italic letter is the answer 318
33. The velocity of all electromagnet waves in a vacuum is 3.0 x 108ms-1.What is the wavelength of radio waves transmitted at 100 MHz ?( Velocity, v = f )
A. 0.30 mB. 3.0 mC. 30 mD. 300 m
34. Which of the following electromagnetic spectrum has the longest wavelength?
A. MicrowaveB. Radio waveC. Visible lightD. Gamma rays
35. Which of the following waves is used as carrier waves in communication?
A. Heat wavesB. Video wavesC. Radio wavesD. Audio waves
36. Which of the following radio component is used to demodulate the signal receivedby the radio?
A. DiodeB. AerialC. Inductor
D. Capacitor
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PAPER 2
SECTIONA
1. In an experiment to observe various characteristics of electromagnetic wave usingCRO, the wave form is displayed on the screen of the oscilloscope as shown inDiagram 1. The frequency of the wave is 100 MHz.
1 cm
0 5 10 15 20 25 30 mm
-1 cm
DIAGRAM 1
a) What is the amplitude and the wavelength?
Amplitude : 1cm
Wavelength : 5mm..
(2marks)
b) Calculate the velocity of the wave.
V = f
= 100 x 5 mm = 500 mm s-1
c) Sketch the wave form that will be obtained when
(i) the frequency of the wave is doubled
(2marks)
(ii) the amplitude of the wave is doubled.
(2marks)
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SES 1511 Kelantan 2007 *The bolded and italic letter is the answer 320
i. ........................................
SECTION B
1. Diagram 2 shows the electromagnetic spectrum.
X Microwaves InfraredVisible
light Ultraviolet YGamma
ray
(a) Name waves X and Y.DIAGRAM 2
i. X: Radio waves.
ii. Y:X - ray
. (2 marks)
(b) State two properties of wave X that can be applied in communication.
Modulation with audio signal
............................................................ Can travel through vacuum
ii. ..(2 marks)
(c) Name the waves used for satellites and mobile phone communication.
Microwave
.(1 mark)
(d) The speed of a radio signal is 3 x 108 ms-1. Calculate the time taken to transmit aradio signal for 6000 km.
t = Distance /velocity= 6 x 10 6 / 3 x 10 8= 0.02 s
2. Complete Table 1 with the correct answers.(2 marks)
Electronic component Symbol function
Inductor To induce electromotive force
Diode .. To
de
mod
ula
te
th
e r
ad
io
sig
na
l.into the audio and radio
..
Resistor Control magnitudeofcurrent .
Capacitor To store charge
Transistor Act as current amplifier.
TABLE 1 (5 marks)
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SES 1511 Kelantan 2007 *The bolded and italic letter is the answer 321
3. Diagram 3 shows a radio receiver system
Z
Tuner Amplifier
Component X Component Y
DIAGRAM 3
(a) Name component X and component Y in the circuit.
X:
Va
ri
ab
le
ca
p
ac
ito
r
Y: Transis
tor. (2 marks)
(b) State the function of component X.
To choose/ select radio waves of different frequency
(1 mark)
(c) (i) What is Z?
Speaker..
(ii) State the function of Z.
Changes audiosignals intosoundwaves
.(2 marks)
(d) Diagram 4 shows the transformation of the radio waves when it flows through V.
(i) What is V?
A BDIAGRAM 4
Amplifier/ Transistor
(ii) What is the difference between radio waves A and B?
Waves B have higher amplitude than waves A
(1 mark)
(1 mark)
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SES 1511 Kelantan 2007 *The bolded and italic letter is the answer 322
4. Diagram 5 shows a block diagram of radio transmission system.
R
Oscillator 1 Q 3 Amplifier
P 2
DIAGRAM 5
(a) i) What is Q?
Modulator.(1mark)
ii) State the function of Q.
To combine carrier waves/radio waves and audio waves.....
(1mark)
(b) State the function of P .
To change sound waves to audio waves / electrical signal.. ..
(1mark)
c) Mark the correct number for wave form that comes out from each component.
3
1
2 (3 marks)
(c) State the function of the R
Tosend out thesignalsasradio waves. (1mark)
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SES 1511 Kelantan 2007 *The bolded and italic letter is the answer 323
5. Diagram 6 shows a Global Communication Network.
(a) What type of wave is used in the communication?
Microwaves.(1mark)
(b) Give three advantages using that wave in communication.
i)Si
gn
al
s
ca
rri
ed
very
fa
st
(a
t a
spe
ed
oflig
ht
)
ii) Moreinformation can besent andreceivedthroughsatellite..communication system
iii) Signals receivedinsatellitecommunications areclearerandof .better quality (3 marks)
(c) Besides telecommunication, give two other uses of satellites.
i) U
se
d
for
sp
ac
e
ob
se
rvat
io
n
(A
stro
no
my
sa
te
lli
tes
)..
ii) Studiesonthelocationsoftheearth resources (Remote-sensing) ..
(2 marks)
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Sound Ampl itude of graph
Soft
Loud
SECTION C
1. Study the following statement.
Different loudness of sound makes different sizes of amplitude on the soundwaves formed on oscilloscope screen.
You are given an oscilloscope.
a) Suggest a hypothesis to investigate the above statement. (1mark)
b) Describe an experiment to test your hypothesis in 1(a) based onthe following criteria.
(i) Aim of the experiment (1mark)
(ii) Identification of variables (2 marks)(iii) List of apparatus and materials (1mark)(iv) Procedure or method (4 marks)(v) Tabulation of data (1mark)
ANSWER
a) If the loudness of sound increases, the amplitude of the sound waves alsoincreases
b) i) To study the effect of different sound loudness on the amplitude of sound
waves.
ii) Manipulated variable : The volume of sound Responding variable: The amplitude of sound wave Constant variable : Using thesame student/ microphone.
iii) Apparatus: Single beam oscilloscope and microphone. iv)
Procedure :
1. Connect the single beam oscilloscope to the power supply.2. Set the time base on.
3. Connect the probe to the microphone and talk softly on themicrophone.
4. Repeat procedure 3 by talking louder5. Observe and sketch the waves displayed on the screen. v)
Tabulation table
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SES 1511 Kelantan 2007 *The bolded and italic letter is the answer 325
2. a) State four basic component in a simple radio and their functions. (4 marks)
b) Diagram below shows three communication instruments which use microwaves.
Satellites Television
Communication instrumentsusing microwave
Mobile phone
Study the above communication instruments. You are required to develop aconcept of microwave.
Your answer should be based on the following aspects:
Identify two common characteristics of a microwave. Develop an initial concept of a microwave . Give one example of a communication instrument which uses
microwave and one which does not use radio waves. Give the reason foreach example.
Develop the actual concept of microwave. (6 marks)a)
Name of components Function
Resistor Controls the magnitude of the current in thecircuit.
Capacitor Used with the inductor to determines thefrequency of the radio that will be detected.
Store charges and electrical energy.
Allow alternating current to pass through but not thedirect current.
Channel the flow of radio frequency carrier wave intothe earth to eliminate the unwanted radio signals.
Diode Allow the current to flow in one direction.
Act as rectifier to separate the audio frequency signalsfrom radio frequency signals through demodulation.
Transistor Amplify audio frequency signals before sending
them to the loudspeaker or earphones.
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b)
Two common characteristics
Sending information very fast
Can travel through vacuum/outer space Can carry signal Has very short wavelength
Initial concept
The wave that could send information very fast and has a very shortwavelength is microwave
Other example
Pager because it can sends information very fast
Non-example
loud speaker newspaper because the transmission is slow
Actual concept
A microwave is a wave which sends information very fast and hasvery short wavelength
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