Ch 16 Communication St

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 )


frequency wave

Combine the audiofrequency wave with

radio waves.


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


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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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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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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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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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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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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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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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

Documents

Ch 16 Communication St