COMMUNICATION SYSTEM FUNDAMENTALS

COMMUNICATION SYSTEM FUNDAMENTALS

1st Edition

ONG HUI NIANG AZIMAH BINTI JUSOH @ ALIAS ONG HUI CHING

COMMUNICATION SYSTEM FUNDAMENTALS

Ong Hui Niang Azimah Binti Jusoh @ Alias Ong Hui Ching

COMMUNICATION SYSTEM FUNDAMENTALS

Author Ong Hui Niang Azimah Binti Jusoh @ Alias Ong Hui Ching

Published by POLITEKNIK SULTAN HAJI AHMAD SHAH SEMAMBU 25350 KUANTAN

Copyright ©2022, by Politeknik Sultan Haji Ahmad Shah Materials published in this book under the copyright of Politeknik Sultan Haji Ahmad Shah.

All rights reserved. No part of this publication may be reproduced or distributed in any form or by means, electronic, mechanical, photocopying, recording, or otherwise or stored in a database or retrieval system without the prior written permission of the publishers.

In the name of Allah, the Most Gracious and the Most Merciful, Alhamdulillah and the praise of Allah for the strength and His Blessing which enabled us to complete the documentation of this eBook. We would like to express our appreciation to our POLISAS Head of Electrical and Engineering Department, Head of DEP program for their supports and encouragement in producing the eBook.

We gratitude also to family and friends who have been involved either directly or indirectly because without their supports, this eBook not have been completed.

i

The contents of this eBook is written based on the Malaysian polytechnics syllabus for DEP30013 Communication System Fundamentals course taken by Electrical and Electronic Engineering (Communication) and Electrical and Electronic Engineering students. There are four topics in this course. Each topic will be compiled in eBook format separately. So, the first edition of this eBook is related to chapter 1 and chapter 2.

The content of the eBook is divided into Chapter 1: Introduction to Communication System and Chapter 2: Modulation Techniques. Exercises and problems are also provided to test the reader’s understanding and the answers. are given at end of the chapter.

We hope this eBook will be useful to the students, instructors as well

as

others

interested

in

Communication

System

Fundamentals. We welcome feedback and comments for further improvement.

Thank you All. ii

COMMUNICATION SYSTEM FUNDAMENTALS

TABLE OF CONTENTS Edition 1 • 2022

i ii

PREFACE

1

INTRODUCTION TO COMMUNICATION SYSTEM

1

1.1

Communication System

4 10

1.2 1.3

Noise, Distortion And Interference Signal To Noise Power Ratio (Snr)

11

1.4

Frequency Spectrum

14 15

1.5 1.6

Bandwidth Wavelength (λ)

15 16

1.7 1.8

Information Capacity Understand Tranmission Modes

18

1.9

Types Of Communication System

21

Exercise and Answer

25

MODULATION TECHNIQUES

25 26

2.1 2.2

Modulation And Demodulation Types Of Modulation

27

2.3

Analog Modulation

30

2.4

Digital Communication

32 33 42

2.5

M-Ary Coding

2.6 2.7

Pulse Modulation Digital Modulation

46

Exercise And Answer

ACKNOWLEDGEMENT

COMMUNICATION SYSTEM FUNDAMENTALS

CHAPTER 1 INTRODUCTION TO COMMUNICATION SYSTEM 1.1

COMMUNICATION SYSTEM

Communication system is a process of transmission, reception and processing the information between two or more locations through transmission medium. Examples:  People-people, people-peoples,  computer-computer, computer-computers  People - computer TELECOMMUNICATION is a process of sending the information between two or more locations through transmission medium at far distance. TELE (in Latin) is a Far and COMMUNICATION is a process of sending the information between two or more locations through transmission medium. In earlier times, telecommunications involved the use of visual signals or audio signals such as;  Smoke signals, Flag signals  Coded drum beats, Lung-blown horns  Visual telegraphy (or Semaphore in 1792) In the modern age of electricity and electronics, telecommunications have typically involved;

 Telegraph (1839), Telephone (1876), Teletype, Radio, TV  Microwave Communication – Satellite, Radar, Cellular  Data Communication – Internet, Computer communication  Fiber Optic Communication.

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COMMUNICATION SYSTEM FUNDAMENTALS

Figure 1.0: Basic Communication System

message INFORMATION SOURCE

TRANSMITTER

signal

signal TRANSMISSION MEDIUM or CHANNEL

RECEIVER

message DESTINATION

SYSTEM NOISE & INTERFERENCE

Figure 1.1: Basic Block Diagram of an Electronic Communication System 1.1.1

ELEMENTS of COMMUNICATION SYSTEM From above Shannon’s basic communication block diagram, there are FIVE (5) elements that must have in basic communication system which are, 1) Information Source 2) Transmitter (Tx) 3) Transmission Medium or Communication Channel 4) Receiver (Rx) 5) Destination 2

COMMUNICATION SYSTEM FUNDAMENTALS

Information Source is the original source that generate the information (audio, text, image or video) that need to be transferred to Receiver. The information that have been generated by source could be an analog form (human voice, audio) or digital form (binary coded numbers, alphanumeric codes). Examples: people, computer, hand phone, electronic devices. Transmitter is a collection of one or more electronic devices or circuits that converts the original source information to a form more suitable for transmission over a particular transmission medium.

Includes the modulation, multiplexing and encoding process. Examples: Modulator, Multiplexer, Transducer, Encoder, Light Source etc. Transmission Medium / Channel is a media/link/path that capable to transfer the electronic signal from Transmitter to receiver. Examples: Twisted Pair Cable, Coaxial Cable, Fiber Optic Cable, Waveguide, Microstrip, Free Space, etc. Receiver is a collection of one or more electronic devices or circuits that accept the transmitted signals from the transmission medium and then convert back to their original information form. Includes the demodulation, demultiplexing and decoding process. Examples: Demodulator, Demultiplexer, Transducer, Decoder, Photo detector, etc. Destination is anything that receive the transmitted information and capable to store them. Examples: people, computer, hand phone, electronic devices. System Noise is any noise unwanted electrical signals that interfere with the information signal. Examples: Atmospheric noise, Thermal Noise, Man-made Noise, Cosmic Noise, Internal Noise etc.

EXAMPLE

a) Data Communication System

Information Source

Transmitter

Transmission Medium or Channel

3

Receiver

Destination

COMMUNICATION SYSTEM FUNDAMENTALS b) Telephony Communication System

Figure 1.2: Example for Data Communication System and Telephony Communication System

1.1.2 INFORMATION, MESSAGE AND SIGNAL Information is an original source information which do NOT processed yet by transmitter or do NOT converted into signal. It can be stored in people or any devices like computer, digital camera, video camera, recorder etc. Examples: audio, alphanumeric, text, image, video. Message represents the content of Information. Signal is a converted information into time-varying or spatial-varying quantity that could be measured. Signal can be an electric current, light or electromagnetic wave which is used to convey data from one place to another. A signal may be expressed as a function of time or frequency. When a signal is expressed as a function of time, there are two basic types of signals.  Digital Signal (Discrete-time signal)  Analog Signal (Continuous-time signal) DIGITAL SIGNAL is a discrete or finite signal that generates and process data in form of zeroes and ones (0s and 1s). It has finite (countable) set of amplitudes. For example; binary-encoded digit, alphanumeric codes, computer-generated data, digitally encoded analog signals etc.

ANALOG SIGNAL is a continuous or infinite signal that generates continuous values, leading to continuous wave pattern. It has infinite (uncountable) of amplitudes. For example; human voice, audio etc.

4

COMMUNICATION SYSTEM FUNDAMENTALS

1.2 NOISE, DISTORTION & INTERFERENCE Noise is unwanted signal from sources other than the transmitted signal source. It is a signal that does not convey any information. Electrical noise is defined as any unwanted electrical signal that falls within the passband of the signal. For example, in audio recording, any unwanted electrical signals that fall within the audio frequency band of 0 Hz to 15kHz will interfere the music will be considered as NOISE. Figure 1.3 shows the signal with noise and the signal without noise.

Signal with noise

Signal without noise

Figure 1.3: Signal with and without noise Particularly noise can be divided into two general categories;  Correlated Noise (No Signal, No noise)  Uncorrelated Noise (Always has noise in the system) Uncorrelated Noise is divided into 2 groups;  External Noise  Internal Noise 1.2.1 EXTERNAL NOISE External Noise is the noise which is generated outside the device or circuit system. External noises are somewhat uncontrollable and these are:

5

COMMUNICATION SYSTEM FUNDAMENTALS

 Atmospheric Noise  Extra-Terrestrial/ Space Noise  Man-made or Industrial Noise Atmospheric Noise •

It is caused by lighting discharge in thunderstorm and other natural disturbance in atmosphere. It spreads over the complete frequency spectrum which is used for radio communication. The receiving antenna not only picks up the desired signal but also the noise from thunderstorm and various disturbance causes at the output. Thus, large atmospheric noise is generated in low or medium frequency band (LF @ MF) while very little noise is generated in very high frequency (VHF) band.

Space Noise •

Space noise is divided into two categories;  Solar Noise Solar noise is an electrical noise generated from the sun heat. This is continuous radiation from sun. For example, result from large body of very high temperature (60000°C) will radiate electrical energy spectrum which is in the form of noise which spread over all the spectrum used for radio communication.  Cosmic noise Cosmic noise is an electrical noise generated from the galaxies such as star. The star and distant also like a sun which have high temperature. Therefore, these stars radiate the noise in the same way as sun. The noise receives from the distant, star is known as thermal noise and distributed almost uniformly over the entire and almost effects on communication of radio waves.

Man Made Noise •

It is an electrical noise which produced by a source like automobiles such as an aircraft ignition, electric motors, switch gear leakage from higher voltage light, etc. Fluorescent 6

COMMUNICATION SYSTEM FUNDAMENTALS

light and many of man-made noise like electrical machine are intensive in industrial area and populated urban area.

1.2.2 INTERNAL NOISE Internal Noise is the noise which is generated inside the communication system, within a device or circuit. It is produced by properly design of receiver circuitry and these are:  Thermal Noise  Shot Noise  Transit-time Noise Thermal Noise •

Thermal noise is produced by the random motion of electrons in a conductor due to heat (thermal agitation). Each electron in a conductor carry a unit negative charge and its velocity is proportional to the absolute temperature because this type of electron movement is totally random and, in all directions, it is sometimes called random noise.

Thermal noise is present in all electronic communications system. It is a form of additive noise which meaning that it cannot be eliminated and it increases in intensity with the number of devices and circuit length. Also known as Brownian Noise, Johnson Noise, and White Noise (because the random movement of electrons is at all frequencies).

Shot Noise •

Shot noise is caused by the random arrival of current carriers (holes and electrons) at the output element of an electronic device, such as a diode, field-effect transistor (FET) or bipolar transistor (BJT). These random arrival of the carriers because of the random paths and difference distance of travels. Shot noise is sometimes called transistor noise and is additive with thermal noise.

7

COMMUNICATION SYSTEM FUNDAMENTALS

Transit - Time Noise •

Transit-time noise is any modification to a stream of carrier signals as they pass from the input to the output of a device (such as from the emitter to the collector of a transistor) produces an irregular, random variation. Transit-time noise in transistors is determined by carrier mobility, bias voltage, and transistor construction.

1.2.3 INTERFERENCE Interference is a form of external noise which means “to disturb or detract from”. Interference is when information signals from one source produce frequencies that fall outside their allocated bandwidth (Harmonics) and interfere with information signals from another source. Most of interference occurs when harmonics or cross-product frequencies from one source fall into the passband of a neighboring channel. For example, radio channels Interference where a channel is interfered by adjacent radio channel’s frequencies. Some possible types of interference are: i.

Adjacent-Channel Interference (ACI) - caused by extraneous power from a signal in an adjacent channel.

ii.

Co-Channel Interference (CCI) or Crosstalk - is crosstalk from two different radio transmitters using the same frequency.

iii.

Electromagnetic Interference (EMI) - is disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source.

iv.

Inter-carrier interference (ICI) - caused by doppler shift in OFDM modulation

1.2.4 DISTORTION •

Distortion is any changes in the original signal which has a corrupting effect on its form or shape. It is the modification of the original shape (or other characteristics) of original information signal. It creates unwanted frequencies (Harmonics) that interfere with the original signal and degrade the performance. It is a kind of Correlated noise which the

8

COMMUNICATION SYSTEM FUNDAMENTALS

noise(distortion) is exist when the signal is exist. Below diagram show various types of distortion of original signal after passed through various distorting functions. The original signal is square wave shape but have been distorted, become a sine wave shape.

Figure 1.4: Various Types of Distortion Some possible types of nonlinear distortion are:  Harmonic Distortion/ Amplitude Distortion: Occurs when unwanted harmonics of a signal are produced through non-linear amplification. (Noted: Harmonics are integer multiples of the original signal’s frequency, e.g: 2f1, 3f1..).  Intermodulation Distortion: The generation of unwanted sum (f1+f2) and difference (f1-f2) frequencies (or crossproduct frequencies) produced when 2 or more signals mix in a nonlinear device.  Frequency Response Distortion: A distortion that occurs when different frequencies are amplified by different amounts, caused by filters.

9

COMMUNICATION SYSTEM FUNDAMENTALS

For example, the non-uniform frequency response curve of AC-coupled cascade amplifier.

In the audio case, this is mainly caused by room acoustics, poor loudspeakers etc.  Phase Distortion: A distortion that occurs due to the reactive component, such as capacitive reactance or inductive reactance. As the results, a phase shift occurs between components of the original signal.

1.3 SIGNAL TO NOISE POWER RATIO (SNR) The ratio of Signal Power(S) to the Noise Power(N) which corrupting the signal. Signal-to-Noise Power Ratio is also called as SNR or S/N. SNR is a defining factor when it comes to quality of measurement where a high SNR guarantees clear acquisitions with low distortions caused by noise. The better your SNR, the better the signal stands out, the better the quality of your signals, and the better your ability to get the results you desire.

1.3.1 HOW TO CALCULATE SNR? SNR (unit less):

SNR =

2

VS /Rin 2

SNR =

VN /Rout

S PS = N PN

where; S = signal power (watts) N = noise power (watts) V = signal voltage (volts) S

V = noise voltage (volts) N

R = input resistance (ohms) in

R = output resistance (ohms) out

SNR (dB): S SNR(dB) = 10log   SNR(dB) N

 V 2 /R SNR(dB) = 10log 10log  S2 in SNR(dB)  V /R out out  N

10

   

COMMUNICATION SYSTEM FUNDAMENTALS

1.3.2 NOISE FACTOR & NOISE FIGURE Noise Factor (F) and Noise Figure (NF) are figures of merit used to indicate how much the signal to noise ratio deteriorates as a signal passes through a circuit or series of circuits.

Noise Factor (F):

F= F=

Input signal - to - noise power ratio Output signal - to - noise power ratio SNRin

SNR out

=

S in Nin S out Nout

(unitless)

Noise Figure (NF) is simply the noise factor stated in dB and is a parameter commonly used to indicate the quality of a receiver.

Noise Figure (NF): NF(dB) = 10logF  SNRin   NF(dB) = 10log   SNRout    Sin  Nin  NF(dB) = 10log     Sout Nout  

1.4 FREQUENCY SPECTRUM

Figure 1.5: Electromagnetic Frequency Spectrum 11

COMMUNICATION SYSTEM FUNDAMENTALS

Radio wave band:1MHz - 1THz Microwave band: 0.3GHz - 300GHz (0.3THz) Fiber optic band: 0.3THz – 300THz

The electromagnetic frequency spectrum is divided into subsections, or bands or range with each band having a different name and boundary. The International Telecommunications Union (ITU) is an international agency in control of allocation frequencies and services within the overall frequency spectrum. The ITU band designations are summarized as follows: 1. Extremely Low Frequencies (ELF) - are signals in the 30 Hz to 300 Hz range and include ac power distribution signals (60Hz) and low frequency telemetry signals.

2. Voice Frequencies (VF) - are signals in the 300 Hz to 3000 Hz range and include frequencies generally associated with human speech.

3. Very Low Frequencies (VLF) - are signals in the 3 kHz to 30 kHz range, which include the upper end of the human hearing range. VLFs are used for some specialized government and military systems, such as submarine communications.

12

COMMUNICATION SYSTEM FUNDAMENTALS

4. Low Frequencies (LF) - are signals in the 30 kHz to 300 kHz range and are used primarily for marine and aeronautical navigation.

5. Medium Frequencies (MF) - are signals in the 300kHz to 3 MHz range and are used primarily for commercial AM radio broadcasting (535kHz – 1605kHz).

6. High Frequencies (HF) - are signals in the 3MHz to 30 MHz range and are often referred as short waves. Most two-way radio communications use this range. Amateur radio and Citizens band (CB) radio also use signals in this range.

7. Very High Frequencies (VHF) - are signals in the 30 MHz to 300 MHz range and are used for mobile radio, marine and aeronautical communications, commercial FM broadcasting, and commercial television broadcasting of TV1 and TV2.

8. Ultra-High Frequencies (UHFs) - are signals in the 300 MHz to 3 GHz range and are used by commercial television broadcasting, land mobile communication services, cellular telephones, certain radar, navigation systems, microwave and satellite radio systems.

9. Super High frequencies (SHF) - are signals in the 3GHz to 30 GHz range and include the majority of the frequencies used for microwave and satellite radio communications systems.

10. Extremely High Frequencies (EHF) - are signals in the 30 GHz to 300 GHz range and are seldom used for radio communications except in very sophisticated, expensive, and specialized applications.

11. Infrared - Infrared frequencies are signals in the 0.3THz to 300 THz range and are not generally referred to as radio waves. Infrared refers to electromagnetic radiation generally associated with heat. Infrared signals are used in the heat-seeking guidance systems, electronic photography, and astronomy.

12. Visible Light - Visible light includes electromagnetic frequencies that fall within the visible range of humans (0.3 PHz to 3 PHz). Light wave communications are used with optical

13

COMMUNICATION SYSTEM FUNDAMENTALS

fiber systems, which in recent years have become a primary transmission medium for electronic communications systems.

13. Ultraviolet rays, X rays, Gamma rays, and Cosmic rays - Ultraviolet rays, X rays, gamma rays, and cosmic rays have little application to electronic communications.

1.5 BANDWIDTH (BW) Bandwidth (BW) = the range of frequencies = the difference between the highest and the lowest frequencies. The bandwidth of a frequency spectrum is the range of frequencies contained in the spectrum. The bandwidth of an information signal is simply the difference between the highest and lowest frequencies contained in the information.

BW (Hz) = frequency range = f

max

–f

min

BW indicates the capacity of data. The larger size of BW means the bigger capacity of data and more data could be transfer at one time.

Figure 1.6: Bandwidth

14

COMMUNICATION SYSTEM FUNDAMENTALS

1.6 WAVELENGTH (λ) Wavelength is the length of one cycle (or one oscillation) of a waveform. The relationship among frequency f, light velocity c, and wavelength λ is expressed mathematically as:

wavelegth, λ =

c f

where; λ = wavelength (meter) c = velocity of light (3 x 108 m/s) f = frequency (Hz) From above equation, wavelength is inversely proportional to the frequency of the wave and directly proportional to the velocity of propagation.

Figure 1.7: Wavelength

1.7 INFORMATION CAPACITY Information Capacity (I), unit: bps Information capacity is a measure of how much information can be propagated through a communications system. It is a function of bandwidth and transmission time. Information 15

COMMUNICATION SYSTEM FUNDAMENTALS

capacity represents the number of independent symbols that can be carried through a system in a given unit of time. Usually expressed as a bit rate.

Shannon’s Limit In 1948, a mathematician Claude E. Shannon from Bell Telephone Laboratories developed a useful relationship among Information Capacity (I) of a communication channel, Bandwidth (BW), and signal to noise ratio (S/N). The higher the signal-to-noise ratio, the better the performance and the higher the information capacity. Mathematically stated, the Shannon Limit for information capacity is;

S  I = B log 2 1 +   N or S  I = 3.32 B log10 1 +   N 1.8 UNDERSTAND TRANSMISSION MODE Transmission mode is the flow of information signal between two points. These modes direct the direction of flow of information signal. There are three modes of transmission for communications circuit:  Simplex  Half duplex  Full duplex Simplex Information signal flows only in one direction on the transmission medium. Simplex lines are also called receive- only, transmit- only, or one- way- only lines. Examples: radio broadcast, television broadcast, workstation-monitor.

16

COMMUNICATION SYSTEM FUNDAMENTALS

Figure 1.8: Simplex Half Duplex Information signal flows in both directions but only one direction at a time on the transmission medium. Half duplex communications lines are also called two way alternate or either way lines.

For example, a conversation on walkie-talkies is a half-duplex data flow. Each person takes turns talking. If both talk at once - nothing occurs.

Figure 1.9: Half Duplex Full Duplex Information signal flows in both directions simultaneously. They must be between the same two stations. Full duplex lines are also called two- way simultaneous, duplex, or both- way lines.

Example: local telephone call, website chat.

Figure 1.10: Full Duplex

17

COMMUNICATION SYSTEM FUNDAMENTALS

1.9 TYPES OF COMMUNICATION SYSTEM There are 4 types of Communication System;  Broadcast Communication System  Mobile Communication System  Fixed Communication System  Data Communication System Broadcast Communication System A broadcast is a wireless transmission of audio and video signal to a receiver via radio, television, or others. It is a method of sending a signal where multiple receivers may receive from a single sender. Broadcast is a type of communications called Simplex (data flow in one direction). There is no interaction between the originator of the content and the user of the content, so if the content delivery is delayed by even a second or so, there will be little effect on the value of the communications.

Historically, there have been several different types of electronic broadcasting media: 1. Telephone broadcasting (1881) 2. Radio broadcasting (1906) 3. Television broadcasting (telecast) (1925) 4. Cable radio (1928) 5. Satellite television (1974) and Satellite radio (1990) 6. Webcasting of video/television (1993) and audio/radio (1994) streams Mobile Communication Mobile communication system is a wireless communication in which voice and data information is emitted, transmitted and received via microwave signals. Example: talking on the hand 18

COMMUNICATION SYSTEM FUNDAMENTALS

phone, SMS via hand phone and so on. It is a Full Duplex communication (data flow in 2 directions simultaneously). Using GSM (Global System for Mobile) which is a standard set developed by the European Telecommunications Standards Institute (ETSI)

Figure 1.11: Block Diagram of Mobile Communication A wireless communication link includes a transmitter, a receiver, and a channel as shown in Figure. Most links are full duplex and include a transmitter and a receiver or a transceiver at each end of the link.

Figure 1.12: Wireless Mobile Communication System Above figures show the wireless mobile communication system with different system;  Mobile - base station  Peer-to-peer 19

COMMUNICATION SYSTEM FUNDAMENTALS

 Mobile-repeater-mobile  Mobile-satellite Fixed Communication Fixed Communication is a full-duplex (FDX) or sometimes double-duplex system, allows communication in both directions using fixed line. Example: Land-line telephone networks. Using Public Switching Telephone Network (PSTN) which is a standard set developed by ITU-T. Now, Malaysia is moving towards NGN (Next Generation Network).

Figure 1.13: Land-line Telephone Network Data Communication Data communication is the process of transferring digital information (usually in binary form) between two or more points. Example: computer communications (because much of the information is exchanged between computers and peripheral devices). Data may be as simple as binary ones and zeros, or it may include complex information, such as digital audio or video.

20

COMMUNICATION SYSTEM FUNDAMENTALS

EXERCISE 1. Define information source and transmission medium in element of communication system.

2. Define communication system.

3. Explain FOUR (4) types of communication system.

4. For an amplifier with an output signal power of 10W and an output noise power of 0.01W, determine the signal to noise power ratio.

5. For an amplifier with an output signal voltage of 4V, and output noise voltage of 0.005V and an input and output resistance of 50Ω, determine the signal-to-noise power ratio.

6. For an amplifier with an output signal power of 100W and an output noise power of 0.02W, determine the signal to noise power ratio.

7. For an amplifier with an output signal power of 1000W and an output noise power of 0.04W, determine the signal to noise power ratio.

8. An amplifier has the output signal voltage 8V and output of noise voltage 0.006V. If the input resistance is 50Ω and the output resistance is 75 Ω, what is the signal to noise power ratio of an amplifier?

9. For a standard telephone circuit has an output signal power of 100W, an output noise power of 0.01W, and a bandwidth of 4.3 kHz. Determine its signal to noise power ratio in dB and information capacity.

10. For a standard telephone circuit has an output signal power of 100W, an output noise power of 0.01W, and a bandwidth of 2.7kHz. Determine its information capacity.

21

COMMUNICATION SYSTEM FUNDAMENTALS

ANSWER 1.

Information source is the original source that generate the information (audio, text, image or video) that need to be transferred to Receiver. Transmission Medium or Communication Channel is a media/link/path that capable to transfer the electronic signal from Transmitter to receiver.

2.

Communication system is a process of transmission, reception and processing the information between two or more locations through transmission medium.

3.

Broadcast Communication System Is a wireless transmission of audio and video signal to a receiver Mobile communication System Is a wireless communication in which voice and data information is emitted, transmitted and received via microwaves Fixed Communication System Is a full duplex (FDX) or sometimes double-duplex system, allows communication in both directions using fixed line.

Data Communication System Is the process of transferring digital information (usually in binary form) between two or more points.

4.

SNR = 10 log (S/N) = 10 log (10/0.01) = 10 log 1000 = 30dB

22

COMMUNICATION SYSTEM FUNDAMENTALS

5.

 VS 2 /Rin SNR(dB) = 10log 10log  2 SNR(dB)  V /R out out  N

   

= 10log (42 /50)/(0.0052/ 50) = 10log (0.32/0.5µ) = 58.06dB 6.

SNR = 10 log (S/N) = 10log (100/0.02) = 10log 5000 = 36.99dB

7.

SNR = 10log (S/N) = 10log (1000/0.04) = 10log 25000 = 43.98dB

8.

 VS 2 /R in SNR(dB) = 10log 10log 2 SNR(dB)  V /R out out  N

   

= 10log ( 82 / 50) / (0.0062 / 75) = 64.28dB 9.

SNR (dB) = 10 log (PS/PN) =10 log (100/0.01) = 10 log 10000 = 40dB 23

COMMUNICATION SYSTEM FUNDAMENTALS

I

= 3.32 B Log10 (1+ S/N) = 3.32 (4300) Log10 (1+ 100/0.01) = 3.32 (4300) Log10 10001 = 3.32 (4300) (4) = 57.10 kbps

10.

I

= 3.32 B Log10 (1+ S/N)

= 3.32 (2700) Log10 (1+ 100/0.01) = 3.32 (2700) Log10 10001 = 3.32 (2700) (4) = 35.86 kbps

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COMMUNICATION SYSTEM FUNDAMENTALS

CHAPTER 2 MODULATION TECHNIQUES

2.1 Modulation and Demodulation Modulation is a process of changing one or more properties of the high frequency analog carrier signal either its amplitude, frequency or phase in proportion with the values of the low frequency information signal.

Information Signal (Low Frequency)

Modulator

Modulated Signal (High Frequency)

Carrier Signal (High Frequency)

Figure 2.1: Modulation Process The analog or digital information signals combines with the carrier in the modulator to produce a high frequency modulated signal. Modulated signal is the carrier signal that has been changed by information signal. The modulation is performed in a transmitter while the demodulation is performed in a receiver.

Modulated Signal (High Frequency)

Demodulator

Demodulated Signal (Low Frequency)

Figure 2.2: Demodulation Process Demodulation is the reverse process of modulation where the information signal is extracted from the modulated signal in the demodulator. The demodulated signal is the original information signal.

25

COMMUNICATION SYSTEM FUNDAMENTALS

2.1.1 Why Modulation is necessary? i.

Increase the frequency of information signal ii.

Convert analog signal to digital signal and vice versa iii.

To prevent interference between the same frequency band signals that are transmitted at the same time. iv.

To increase the bandwidth of the signal. v.

To multiplex more number of signals. vi.

To reduce the antenna height and size. vii.

To reduce equipment complexity.

2.2

Types of Modulation

Modulation Types

Analog Modulation

Amplitude Modulation (AM) Frequency Modulation (FM) Phase Modulation (PM)

Digital Communication

Pulse Modulation

Digital Modulation

Pulse Width Modulation (PWM)

Amplitude Shift Keying (ASK)

Pulse Position Modulation (PPM)

Frequency Shift Keying (FSK)

Pulse Amplitude Modulation (PAM)

Phase Shift Keying (PSK)

Pulse Code Modulation (PCM)

Quadrature Amplitude Modulation (QAM)

Figure 2.3: Types of Modulation

26

COMMUNICATION SYSTEM FUNDAMENTALS

2.3 Analog Modulation The Information Signal and Carrier signal are both in analog waveform for analog modulation.

Analog Modulation Amplitude Modulation (AM)

Frequency Modulation (FM)

the amplitude (Vp) of the analog carrier signal is varied proportional to the analog information signal.

the frequency (f) of the analog carrier signal is varied proportional to the analog information signal.

Phase Modulation (PM) the phase (Ɵ) of the analog carrier signal is varied proportional to the analog information signal.

Figure 2.4: Types of Analog Modulation 2.3.1 Amplitude Modulation (AM) AM is the process of changing the amplitude of analog carrier signal in proportion with the amplitude of the analog information signal.

The carrier amplitude is simply changed according to the amplitude of the information signal while the frequency and phase of carrier signal remain unchanged. When the information signal amplitude is increased, the carrier signal amplitude also increased and vice versa.

The general equation for a sinusoidal waveform is as below; Where V = amplitude (volts) f = frequency (Hz) θ = phase shift (radians)

V(t) = V sin (2πft + θ)

Hence, the equation for information signal Vm(t), carrier signal Vc(t) and modulated signal are shown in Figure 2.5.

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COMMUNICATION SYSTEM FUNDAMENTALS

Vm(t) = Vm sin (2πfmt)

Vc(t) = Vc sin (2πfct)

VAM(t) = (Vc sin 2πfct)(1 + m sin 2πfmt) Where m = modulation index

Figure 2.5: AM 2.3.2 Frequency Modulation (FM) FM is the process of changing the frequency of analog carrier signal in proportion with the amplitude of the analog information signal.

The amount of carrier frequency changes is proportional to the amplitude of the information signal. As the modulating signal amplitude increases, the carrier frequency increases and vice versa while the carrier amplitude and phase remain constant.

Vm(t) = Vm sin (2πfmt)

Vc(t) = Vc sin (2πfct)

VFM(t) = Vc cos [2πfct + mf sin 2πfmt) Where mf = modulation index

Figure 2.6: FM 28

COMMUNICATION SYSTEM FUNDAMENTALS

2.3.3 Phase Modulation (PM) PM is the process of changing the phase of analog carrier signal in proportion with the amplitude of the information signal.

As the modulating signal amplitude increases, the carrier phase increases and vice versa while the carrier amplitude and frequency remain constant.

Vm(t) = Vm sin (2πfmt)

Vc(t) = Vc sin (2πfct)

VPM(t) = Vc cos [2πfct + mP sin 2πfmt) Where mP = modulation index

Figure 2.7: PM 2.3.4 Comparison of AM, FM and PM Analog Modulation the carrier amplitude waveform varies with the information signal

Frequency Modulation the carrier frequency waveform varies with the information signal

Phase Modulation the carrier phase waveform varies with the information signal

From sinusoidal equation, V(t) = V sin (2πft + θ) by varying the amplitude, V Waveform

by varying the frequency, f Waveform

by varying the phase, θ Waveform

Equation VAM(t) = (Vc sin 2πfct)(1 + m sin 2πfmt)

Equation VFM(t) = Vc cos [2πfct + mf sin 2πfmt)

Equation VPM(t) = Vc cos [2πfct + mP sin 2πfmt)

Figure 2.8: Comparison of AM, FM and PM 29

COMMUNICATION SYSTEM FUNDAMENTALS

2.4

Digital Communication Digital Communication covers a broad range of communication techniques including digital transmission and digital radio.

Digital Communication Digital Transmission

Digital Radio

Pulse Modulation

Digital Modulation

Figure 2.9: Types of Digital Communication 2.4.1 Digital Transmission Digital transmission is a true digital system where digital signals are transferred between two or more points in a communication system.

With digital transmission, there is NO analog carrier and if the information signal is in analog form, it must be converted to digital pulses prior to digital transmission by using Pulse Code Modulation (PCM) technique and converted back to analog form at the receiving end.

The digital transmission required physically medium such as a metallic cable (twisted, coaxial cable) or a fiber optic cable due to digital pulses CANNOT be propagated through a wireless transmission medium (free space).

2.4.2 Digital Radio Digital Radio is a transmitted of digitally-modulated analog carrier signals between two or more points in a communication system.

In digital radio system, digital pulses modulate the analog carrier signal to produce digitally-modulated carrier signal in analog form.

The transmission medium could be a wireless transmission medium (free space) or physically facility (metallic or fiber optic cable) due to modulated signal is in analog form.

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COMMUNICATION SYSTEM FUNDAMENTALS

2.4.3 Basic Elements of Digital Communication System

Figure 2.10: Block Diagram of Basic Elements of Digital Communication System Source Encoder

Digital Information Textual Information Analog Information

Sampler

Quantizer

Encoder

Channel Encoder

Figure 2.11: Formatting Process Element Information Source Source Encoder Channel Encoder Digital Modulator Channel Digital Demodulator Channel Decoder Signal Decoder

Function The source of information can be analog or digital to convert the information signal from source into digital signals (serial bits) by formatting the signals and compressed that signal.

Then, these bits are grouped to form message symbols. For example: PCM process, Character Encoding (ASCII code) process. for error correction coding. It can reduces the probability of error by introduces some redundancy in the message symbols and transform it into code symbols (code words). to convert the serial bits (digital waveform) into electric signals (analog waveform) the physical medium that is used for transmitting signals from transmitter to receiver converts the electric signals back to the serial bits (code symbols). to reconstruct the original serial bits (message symbols) from the code symbols used by the channel encoder and the redundancy contained in the received data to convert back the serial bits (message symbols) into original source information signal

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COMMUNICATION SYSTEM FUNDAMENTALS

2.4.4 Advantages of Digital Communication i. ii. iii.

iv. v. vi.

2.5

Noise Immunity - Digital signals are less susceptible than analog signals to interference caused by noise.

Reduction of errors - Errors caused by noise and interference can be detected and corrected systematically.

High security - Digital system more secure than analog system because the system can be encoded digital data to a unique code (data encryption) and data can only be understood by the sender and receiver only.

Digital circuit easier to be interfaced compare to analog circuits (because there are two levels of digital signals only '1 'and '0').

Ease of processing and multiplexing.

Inexpensive digital circuitry may be used extensively.

M-ary Coding The number of conditions, M possible with n bits is expressed mathematically as; M = 2n

The number of bits, n that necessary to produce a given number of conditions, M is expressed mathematically as; n = log2 M

Assume a digital signal has two levels. Calculate the number of bits is needed per level and draw that digital signals given data are 10110001.

M=2 𝑛𝑛 = 𝑙𝑙𝑙𝑙𝑙𝑙2 𝑀𝑀 𝑛𝑛 = 𝑙𝑙𝑙𝑙𝑙𝑙2 (2) log 2

n = log 2

n = 1 bit

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COMMUNICATION SYSTEM FUNDAMENTALS

2.6

Pulse Modulation Pulse Modulation is a process of sampling the analog information signals into sampled signal before converting those into digital signals.

In Pulse Modulation, the Information Signal is in analog waveform while Sampling Signal is in digital pulses waveform. The properties of sampling pulse signal such as width, position and amplitude will be varied in proportion with amplitude of information signal.

Pulse Modulation

Analog Pulse Modulation

Pulse Width Modulation (PWM)

Pulse Position Modulation (PPM)

Digital Pulse Modulation

Pulse Amplitude Modulation (PAM)

Pulse Code Modulation (PCM)

Figure 2.12: Types of Pulse Modulation 2.6.1 Analog Pulse Modulation

Figure 2.13: Pulse Modulation: (a) Information Signal; (b) Sampling Pulse; (c) PWM; (d) PPM; (e) PAM 33

COMMUNICATION SYSTEM FUNDAMENTALS

 In PWM, the width of the pulses is varied proportional to the analog amplitude information signal. The higher amplitude of Information signal, the wider of pulse.

Amplitude and Position of pulses are constant.  In PPM, the position of the pulses is varied proportional to the analog amplitude information signal. The higher amplitude of Information signal, the farther to the right the pulse is positioned. Amplitude and Width of pulses are constant.  In PAM, the amplitude of the pulses is varied proportional to the analog amplitude information signal. The higher amplitude of Information signal, the higher amplitude of pulse. Width and Position of pulses are constant.

Application of Analog Pulse Modulation • PWM and PPM are used in special-purpose communication systems, seldom used for commercial digital transmission.

• PAM is used as an intermediate form of modulation with PCM, PSK and QAM. 2.6.2 Digital Pulse Modulation Pulse Code Modulation (PCM) is a digital pulse modulation technique that converts an analog signal to a digital signal.

Application of PCM i. Analog to Digital Converter (ADC) device - in Coder ii. Digital to Analog Converter (DAC) device - in Decoder iii. In digital telephony Multiplexing (TDM-PCM) iv. Digital PABX v. Digital Audio recording vi. CD laser disks

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COMMUNICATION SYSTEM FUNDAMENTALS

PCM System

PAM

(a) PCM Transmitter

Analog-to-Digital converter

Analog Signal

Bandpass Filter

Sampler & Hold

Quantizer

Sampling Pulses

(b) Transmission medium

(c) PCM Receiver

Encoder

Serial PCM code (bits)

Regenerative Repeater

Decoder & Hold

Lowpass Filter

Digital-to-Analog converter

Analog Signal

PAM

Figure 2.14: Block Diagram of PCM System

Element Function Bandpass Filter filter limits the analog input signal to a certain bandwidth (fmin to fmax) to enter the Sampler Sampler & periodically samples the analog input signal and convert the Sampling Hold Pulses signal to a multilevel sampled PAM signal Quantizer convert the sampled PAM signal to quantized PAM signal by rounding off the amplitude of sampled signal to quantization levels, L. Encoder convert the quantized PAM signal to a parallel code number. Then, convert the code numbers to a serial binary pulses (encoded words).

Repeater Amplify and regenerate the weaken digital pulses during transmission on transmission line.

Decoder & Convert back he digital pulses signal to multilevel PAM signals Hold Low pass Filter to smooth the staircase amplitude of PAM signals into an analog signal

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COMMUNICATION SYSTEM FUNDAMENTALS

PCM Encoder A PCM encoder consists of 3 processes as shown in Figure 2.15.

Quantization

Figure 2.15: Block Diagram of PCM Encoder a. Sampling • is a process where the information signal (in analog signal) is sampled by sampling pulse signal, which is generated at a certain sampling rate, fs.

• converts an analog signal (in continuous-time signal) to a sampled PAM signal (in discrete-time signal) as shown in Figure 2.16.

• Hence, the amplitude of the sampled PAM signal is varied proportional to the analog amplitude of the information signal.

• Analog information signal is sampled every Ts seconds, where Ts is the sampling interval or sampling period. The reciprocal of the sampling interval is called the sampling rate or sampling frequency and denoted by ƒs, where;

𝒇𝒇𝒔𝒔 =

36

𝟏𝟏 𝑻𝑻𝒔𝒔

COMMUNICATION SYSTEM FUNDAMENTALS

Ts

Ts

Legend: Information Signal Sampled PAM Signal

Figure 2.16: Sampling • Sampling frequency, fs is determined according to Nyquist Sampling Theorem that states:

to reconstruct the original signal, the sampling rate must be at least (minimum) two times the highest frequency contained in the info signal

fs ≥ 2fm(max)

• In Figure 2.17, a sinusoidal wave is sampled with 3 different sampling rates where; i. Sampling at the Nyquist rate, fs = 2 fm(max) (part a) create a good approximation of the original sine wave. ii. Recovered Signal (part b) where fs > 2fm(max) also creates the same approximation, but it is redundant and unnecessary. iii. Recovered Signal for Sampling below the Nyquist rate (part c), fs < 2fm(max) is totally out of shape and does not produce a signal that looks like the original sine wave.

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COMMUNICATION SYSTEM FUNDAMENTALS

a. fs = 2fm(max)

b. fs = 4f m(max)

c. fs = f m(max)

Original Signal

Recovered Signal

Figure 2.17: Recovered Signal with Different Sampling Rate

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COMMUNICATION SYSTEM FUNDAMENTALS

b. Quantization Quantization is a process rounding off the amplitudes of sampled (PAM) signal to quantized value.

The following are the steps in quantization:

Step 1 : Determine the Vmax and Vmin Step 2 : Determine the number of quantization level, L by given number of bits, n L = 2n

Step 3: Find the step size, Δ Δ=

(𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉−𝑉𝑉𝑉𝑉𝑉𝑉𝑉𝑉) 𝐿𝐿

Step 4: Divide the range (between Vmax and Vmin) into L zones with each height of step size value.

Step 5: Determine the midpoint for each zone Step 6: Approximate the value of the sample (PAM) signal to the nearest midpoint value as quantized value

In Figure 2.18, the quantization and encoding process of sampled (PAM) signals are shown. From the figure, the sample amplitudes are between -4V and +4V and are quantized to 8 evenly spaced levels. This mean that L = 8 and Δ = 1V.

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COMMUNICATION SYSTEM FUNDAMENTALS

Code Number

Quantization Level

7

3.5

6

2.5

5

1.5

4

0.5

3

-0.5

2

-1.5

1

-2.5

0

-3.5

3

Δ

1 -1 Legend:

-3

Information Signal Sampled PAM Signal Quantized Signal

Midpoint Sampled PAM Signal Quantized Signal Quantization Error Code Number Binary Code

4

-0.3

-3.9

0.9

3.8

3.5

-0.5

-3.5

0.5

3.5

- 0.5

- 0.2

0 .4

- 0.4

- 0.3

7

3

0

4

7

111

011

000

100

111

Figure 2.18: Quantization and Encoding

• Quantization error is the difference between sampled and quantized value.

Qe = Quantized Signal – Sampled Signal (V) • The Signal-to-Quantization Noise Power Ratio (SQR) is defined by the equation: SQR = 6.02n + 1.76 (dB) where n = number of bits

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COMMUNICATION SYSTEM FUNDAMENTALS

c. Encoding • is a process of translating the quantized signal into a decimal code number. Then this decimal code number is converted to its representative binary sequence as shown in Figure 2.14.

• The number of bits, n for each level of code number depends on the number of quantization level, L used to quantize the samples which can be determined using M-ary formula. n = log2 L PCM Decoder PCM Decoder is to recover an analog signal from a digitized signal by the following steps:

Decoder & Hold

Figure 2.19: Block Diagram of PCM Decoder a. Decoder and Hold • is a circuit that convert the code words into a pulse that holds the amplitude value till the next pulse arrives. It will produce a staircase PAM signal. b. Low-pass Filter • smooth the staircase amplitude of PAM signals into an analog signal which has the same cutoff frequency as the original information signal at sender If the original info signal is sampled at or greater than Nyquist Sampling Rate (fs ≥ 2fm(max) AND if there are enough Quantization levels (L), the original signal would be recovered back with less distortion.

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COMMUNICATION SYSTEM FUNDAMENTALS

2.7

Digital Modulation Digital Modulation is the process of changing one of the characteristics of an analog carrier signal based on the information in digital data.

Digital data needs to be converted into analog signal by Digital Modulation techniques due to only analog signal can be transmitted through free space (wireless) medium but not to digital signal.

Figure 2.20: Digital-to-Analog Conversion 2.7.1

Types of Digital Modulation In Digital Modulation, Information Signal is in digital waveform while Carrier signal is in analog waveform.

Digital Modulation

Amplitude Shift Keying (ASK)

Frequency Shift Keying (FSK)

amplitude of the analog carrier signal is varied proportional to the digital information signal

frequency of the analog carrier signal is varied proportional to the digital information signal

Phase Shift Keying (PSK)

Quadrature Amplitude Modulation (QAM)

phase of the analog carrier signal is varied proportional to the digital information signal

amplitude and phase of the analog carrier signal are varied proportional to the digital information signal

Figure 2.21: Types of Digital Modulation 42

COMMUNICATION SYSTEM FUNDAMENTALS

2.7.2

Application of Digital Communication i. ii. iii. iv. v. vi. vii. viii. ix. x. xi. xii.

2.7.3

ADC – Analog to Digital Converter DAC – Digital to Analog Converter MODEM – Modulator-Demodulator Digital Camera Digital Video Broadband digital subscriber lines (DSL) Telemetry Teleconferencing Compact Disk (CD) Hard Disk Drive Personal Communication System (PCS) Satellite Communication System

Amplitude Shift Keying (ASK) ASK is similar to standard amplitude modulation except there are only two output amplitudes possible. Both frequency and phase remain constant.

When : • data bit ‘1’, the carrier signal has the constant amplitude • data bit ‘0’, the carrier signal has no amplitude Figure 2.22: ASK

2.7.4

Frequency Shift Keying (FSK) FSK is a form of angle modulated, constant amplitude similar to standard FM except the information signal is a binary signal that varies between two discrete voltage levels.

43

COMMUNICATION SYSTEM FUNDAMENTALS

As the binary input signal changes from a logic 0 to a logic 1 and vice versa, the output frequency shifts between two frequencies: logic 1 - frequency (f1) and logic 0 frequency (f0).

As the data changes from bit ‘0’ to ‘1’ or vice versa, the output frequency shifts between two frequencies; • data bit ‘1’ with frequency f1 • data bit ‘0’, with frequency f0 Figure 2.23: FSK 2.7.5

Phase Shift Keying (PSK) PSK is another form of angle-modulated, constant amplitude similar to conventional PM except with PSK the input is a binary digital signal and there are a limited number of output phases possible.

PSK is an M-ary digital modulation scheme where the number of output phases is defined by M = 2n, where n = number of bits and M = number of conditions.

two phases are possible when n = 1, where one phase represents data bit ‘1’ and other phase represents data bit ‘0’.

As the data bit changes from a 1 to a 0 or vice versa, the phase of the output carrier shifts between two angles that are separated by 180º

Figure 2.24: PSK

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COMMUNICATION SYSTEM FUNDAMENTALS

2.7.6

Quadrature Amplitude Modulation (QAM) QAM is a combination of ASK and PSK so that a maximum contrast between each signal unit (bit, dibit, tribit, and so on) is achieved.

The “quadrature” indicates that the phase difference between two carriers is 90 degrees but both carriers have the same frequency.

90 ̊

180 ̊

0 ̊ 270 ̊

Figure 2.25: Constellation Diagram

Figure 2.26: 8-QAM waveform

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COMMUNICATION SYSTEM FUNDAMENTALS

Question 1: Given an audio signal, v(t) = 10 sin 6500t modulates a high frequency carrier signal, v(t) = 20 sin (2π X 106)t. Obtain: a) Carrier Amplitude b) Modulating Amplitude c) Carrier Frequency d) Modulating Frequency e) AM Modulated Signal Expression

Solution : a) b) c) d) e)

Carrier Amplitude, Vc = 20V Modulating Amplitude, Vm = 10V Carrier Frequency, fc = 1MHz Modulating Frequency fm = 6500 / 2π = 1.0345 KHz AM Modulated Signal Expression VAM(t) = (Vc sin 2πfct)(1 + m sin 2πfmt) = (20 Sin 2π(795.77K)t) (1+ m Sin 2π(1.0345K)t)

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COMMUNICATION SYSTEM FUNDAMENTALS

Question 2: With the aid of a diagram, explain the following pulse modulation techniques i) Pulse Width Modulation (PWM) ii) Pulse Position Modulation (PPM) iii) Pulse Amplitude Modulation (PAM)

Solution :

i)

ii)

iii)

• PWM - the width of the pulses is varied proportional to the analog amplitude information signal.

(The higher amplitude of Information signal, the wider of pulse.)

• PPM – the position of the pulses is varied proportional to the analog amplitude information signal.

(The higher amplitude of Information signal, the farther to the right the pulse is positioned).

• PAM - the amplitude of the pulses is varied proportional to the analog amplitude information signal.

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COMMUNICATION SYSTEM FUNDAMENTALS

Question 3: A digital signal has four levels. Calculate the number of bits needed per level and draw that digital signals given data are 1110010100000010.

Solution :

𝑛𝑛 = 𝑙𝑙𝑙𝑙𝑙𝑙2 𝑀𝑀 𝑛𝑛 = 𝑙𝑙𝑙𝑙𝑙𝑙2 (4) n=

log 4 log 2

n = 2 bits

48

COMMUNICATION SYSTEM FUNDAMENTALS

Question 4: A voice signal contains frequency from 300 to 3400 Hz with maximum voltage of 4V. What are the step size value if quantization level is equal to 8? Determine the minimum sampling rate signal and transmission bit rate for digital transmission? Encode each of the quantized signals in Figure 1 into code number and binary code.

Figure 1

Solution : Step Size, ∆ = 2Vmax / L = 2(4) / 8 = 1V

n = log2 L = log2 8 = 3 bits

Minimum sampling rate, fs = 2fm(max) = 2 (3400) = 6800 Hz Bit rate = n X fs = 3 X 6800 = 20.4 Kbps Code Number Binary Code

3

7

5

011

111

101

49

COMMUNICATION SYSTEM FUNDAMENTALS

Question 5: Quadrature amplitude modulation (QAM) is a modulation technique that mixes both amplitude and phase variations in a carrier at the same time which mean amplitude is allowed to vary with phase. QAM signaling is viewed as a combination of ASK and PSK. By referring to Table B1, produce the constellation diagram. Next, illustrate the waveform by the given data, 001100011110101010000 using 8-QAM digital modulation.

Table B1 Binary Input 8-QAM output Amplitude Phase 0 0 0 3V 0° 0 0 1 3V 90° 0 1 0 3V 180° 0 1 1 3V 270° 1 0 0 6V 0° 1 0 1 6V 90° 1 1 0 6V 180° 1 1 1 6V 270°

Solution :

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COMMUNICATION SYSTEM FUNDAMENTALS

REFERENCES (1) Frenzel, L. E. (2016). Principles of Electronic Communication Systems.4th Edition New York: McGraw- Hill Higher Education.

(2) Forouzan, B.A. (2012). Data Communications and Networking. 5th Edition. United States: Mc Graw Hill Education.

(3) McGraw-Hill©the Mcgraw-Hill Companies, Inc., 2004. Chapter 5 Analog Transmission. Retrieved 2022, from https://slidetodoc.com/chapter-5-analog-transmission-1-mc-grawhill-the/ (4) Miller, Gary M. (2008). Modern Electronic Communication (9th ed.). Prentice Hall. ISBN: 0-13225113-2.

(5) Wayne T. (2004). Electronic Communication Systems: Fundamentals Through Advance (6th ed.).

Prentice Hall. ISBN-10: 0130453501 or ISBN-13: 9780130453501 (6) Mohd Azaini Maarof. Abdul Hanan Abdullah. (2003). Komunikasi Data. Universiti Teknologi Malaysia. ISBN 983-52-0298-2.

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