Communication Systems (EE-361)
INTRODUCTION AND COURSE OUTLINES
Dr. Waleed Tariq Sethi
Assistant Professor
Faculty of Electrical Engineering
GIK Institute of Engineering Sciences and Technology
Email : wsethi@giki.edu.pk
Course Books- Reference Books
Pre-requisite:Signals and Systems (EE351)
Textbook
B. P. Lathi & Z. Ding, Modern Digital and Analog
Communication Systems. Int. 4th Ed., Oxford
University Press, 2010.
References
1.Hsu, H. P. (2009). Schaum's outline of signals and systems
(2nd ed.). Columbus, OH: McGraw-Hill Education.
2.Haykin, S. (2009). Communication systems (2nd ed.).
John Wiley & Sons.
3.Couch, II, L. W. (2007). Digital and analog communication
systems (7th ed.). Upper Saddle River, NJ: Prentice Hall.
4.Proakis, J. G., & Salehi, M. (2005). Fundamentals of
Main Course Book
Communication Systems. Upper Saddle River, NJ: Prentice
Hall.
Program Learning Outcomes
Tentative Grade Distribution
Assessment Tools
Quizzes (Surprise + Scheduled)
Assignments
Midterm Examination
Complex Engineering Problem
Final Examination
Percentage
13%
05%
30%
7%
45%
Students are encouraged to solve some assigned homework problems
using the available engineering software, such as MATLAB
Prepared by: Dr. Waleed Tariq Sethi- Ghulam
Ishaq Khan Institute-Spring 2022
Administrative Policies
 According to institute policy, 80% attendance is mandatory to appear
in the final examination.
 In any case, there will be no retake of (scheduled/surprise) quizzes.
 Assignments are due as instructed. Late submission are not allowed.
 Phone’s should be silent. If a ringtone is heard, the call or message
will be shown to all class attendees.
Prepared by: Dr. Waleed Tariq Sethi- Ghulam
Ishaq Khan Institute-Spring 2022
Tentative Lecture Breakdown
Week
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Topic
Introduction to Communication Systems
Introduction to Signals
Analysis and Transmission of Signals
Analysis and Transmission of Signals
Amplitude Modulation (AM), Baseband and carrier,
Double Side Band (DSB)
Quadrature Amplitude Modulation (QAM)
Single Side Band (SSB), Vestigial Side Band (VSB)
Carrier Acquisition, Superhetrodyne AM Receiver
Mid Exam
Angle Modulation: Concept of Instantaneous
Frequency
Bandwidth of Angle Modulated Waves, FM
generation
Demodulation of FM, Interference in Angle
Modulated Systems
FM receiver
Sampling Theorem, Pulse Code Modulation (PCM)
PCM, Differential PCM (DPCM)
Delta Modulation
Final Exam
Prepared by: Dr. Waleed Tariq Sethi- Ghulam
Ishaq Khan Institute-Spring 2022
Related Preparation
Chapter 1&2 Text Book
Chapter 2 Text Book
Chapter 3 Text Book
Chapter 3 Text Book
Chapter 4 Text Book
Chapter 4 Text Book
Chapter 4 Text Book
Chapter 4 Text Book
To be decided
Chapter 5 Text Book
Chapter 5 Text Book
Chapter 5 Text Book
Chapter 5 Text Book
Chapter 6 Text Book
Chapter 6 Text Book
Chapter 6 Text Book
To be decided
Let’s Begin and Dive into
Communication Systems!!
Chapter:1 – Introduction
Contents
• Communication Systems
• Analog and Digital Messages
• Channel effect, SNR and Capacity
• Modulation and its types
• Brief History of Modern Telecommunication
What is Communication?
Communication & Tech??
• Communication has
been the cornerstone
for development of
civilizations.
• Better communication
technology meant fast
advancements.
• Major developments
in
communication
technology.
2022
What is Communication?
• Communication = Transfer of Information
• Old Forms of Communication (Non Electrical)
–
–
–
–
Using Couriers; human messengers, carrier pigeons, post
Using sound; drum beats, gun shots
Using Fire; torches, smoke, SOS
Using light; flashlight, flags
• Non-Electrical Communication: Slow and over short
distances
• Electrical Communication = Using electrical signals
– Long distances, Fast, Reliable, Economical
• Modes of Communication
– Simplex – One directional
– Half-Duplex- Two directional but at different times.
– Full-Duplex – Two directional simultaneously.
Applications – Health Care
Applications – Cell Phones
Prepared by: Dr. Waleed Tariq Sethi- Ghulam Ishaq
Khan Institute-Spring 2022
Emerging Technologies
Analog Messages
Digital Messages
A General Block Diagram for a Communication System
Source
Input
Message
Input
Transducer
Input
Signal
Transmitter
Transmitte
d
Signal
Channel
Received
Receiver
Signal
Output
Signal
Output
Transducer
Output
Destination
Message
Channel Impairments






Delay
Attenuation (loss of power)
Distortion (system imperfections)
Noise (usually from natural
sources)
Interference (non-hostile human
sources)
Jamming (hostile human sources)
Message
• Source:
– Generates a message (often in a non-electrical form)
•
•
•
•
•
Human voice (acoustic signal)
Printed page
Photograph
Video
Text message
• Input Transducer
– Converts the non-electrical message into an
electrical waveform that is called a baseband signal.
Prepared by: Dr. Waleed Tariq Sethi- Ghulam Ishaq
Khan Institute-Spring 2022
Huma
n
Voice
Printe
d Page
Input
Transduce
r
Microphone
Scanner
Photograph
Digital Camera
Video
Video Camera
Text
Messag
e
Keyboard
A General Block Diagram for a Communication System
Source
Input
Message
Input
Transducer
Input
Transmitter
Signal
Transmitte
d
Channel
Signal






Received
Receiver
Signal
Output
Signal
Output
Transducer
Output
Destination
Message
Channel Impairments
Delay
Attenuation (loss of power)
Distortion (system imperfections)
Noise (usually from natural sources)
Interference (non-hostile human sources)
Jamming (hostile human sources)
• Transmitter:
– Modifies the baseband signal into a form suitable for the channel, for
efficient transmission
• Channel
– is the medium of transmission
• e.g. wire, coaxial cable, optical fiber, air, free space, etc.
– Can cause many types of impairment to the signal
Prepared by: Dr. Waleed Tariq Sethi- Ghulam Ishaq
Khan Institute-Spring 2022
A General Block Diagram for a Communication System
Source
Input
Message
Input
Transducer
Input
Transmitter
Signal
Transmitte
Signal




d
Channel
Received
Receiver
Signal
Output
Signal
Channel Impairments
Delay
Attenuation (loss of power)
Distortion (system imperfections)
Noise (usually from natural
sources)
Interference (non-hostile human
sources)
Jamming (hostile human sources)
Output
Transducer
Destination
Message
– “Recovers” the input signal from the received
signal by undoing the signal modifications made
by the transmitter and the channel
Human Voice
Output
Transduce
r
Loudspeaker
Printed Page
Printer
– Converts the output electrical signal into its
original form (message)
Photograph
Printer/Stil
l Monitor
Video
Video
Monitor/T
V
Text Printer, e.g.
telex machine

• Receiver:
• Output Transducer
• Destination

Message
Output
– The unit to which the message is communicated,
Text Message
e.g., the user of the information
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Khan Institute-Spring 2022
Break Down of Communication System
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Information Source
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Input Transducer
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Khan Institute-Spring 2022
Transmitter
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Khan Institute-Spring 2022
Channel
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Khan Institute-Spring 2022
Noise
• Noise is a random and unpredictable signal, usually, from natural sources
– External noise; lightning, solar noise, interference
– Internal noise; thermal motion of electrons in conductors, random emission, diffusion
and recombination of electrons and holes.
• Proper care can minimize or even eliminate external noise
• Proper care can reduce the effect of internal noise but can never eliminate it
• Noise is one of the basic factors that fundamentally limits the
communication rate.
• The signal-to-noise ratio (SNR) is defined as the ratio of signal power to noise power
• The SNR is continuously decreasing along the length of the channel.
• Amplification of the received signal to compensate for attenuation cannot help
improve the SNR, because the noise will be amplified in the same proportion. On the
contrary, an amplifier may decrease the SNR.
Prepared by: Dr. Waleed Tariq Sethi- Ghulam Ishaq
Khan Institute-Spring 2022
The Receiver/Output Transducer
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Destination
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Khan Institute-Spring 2022
LECTURE BREAK!!
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Analog vs Digital Signals
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30
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31
Sampling and Quantization
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Pulse Code Modulation (PCM)
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Khan Institute-Spring 2022
Modulation
•
•
Modulationis the process by which the baseband signal is included in the
properties of a high-frequency carrier.
A carrier is a high-frequency sinusoid and it has the following parameters:
– Amplitude
– Frequency
– Phase
•
•
Modulationis performed by varying one of the carrier parameters in
proportion to the baseband signal.
Accordingly, we have
– Amplitude Modulation (AM)
– Frequency Modulation (FM)
– Phase Modulation (PM)
•
•
At the receiver, the inverse operation is performed. This is called
“Demodulation.”
Demodulationis the process of recovering the baseband signal from the
modulated carrier.
Prepared by: Dr. Waleed Tariq Sethi- Ghulam Ishaq
Khan Institute-Spring 2022
Modulation
Carrier
Baseband Signal=Modulating Signal=Message Signal=Information Signal
Amplitude-Modulated Carrier
Freqency-Modulated Carrier
Prepared by: Dr. Waleed Tariq Sethi- Ghulam Ishaq
Khan Institute-Spring 2022
Why do we need modulation?
• We need modulation for three main reasons:
1.
Efficient Radiation:
• For efficient radiation, the length of the antenna must be at least one tenth of the
wavelength
• For practical antenna size, the signal frequency must be “high”
• For speech signal, most of the power is concentrated in the frequency range of 1003000 Hz. Audible signals have content in the frequency range of 20-20000 Hz. These
frequencies correspond to wavelengths in the range of 15 km to 1500 km. Thus, a
speech signal cannot be radiated from an antenna of a practical size.
• Using a carrier frequency of 500 kHz (MW range), an antenna of length 60 m is needed
(AM Broadcast Station).
Frequency
Wavelength
Minimum
Antenna
• Using a carrier frequency of 800 MHz, an
Length
60 Hz
5000 km
500 km
antenna of length 3.8 cm is needed (Mobile
20 kHz
15 km
1.5 km
Phone)
450 kHz
666 m
66.6 m
1 MHz
300 m
30 m
100 MHz
3m
30 cm
1 GHz
30 cm
3 cm
Prepared by: Dr. Waleed Tariq Sethi- Ghulam Ishaq
Khan Institute-Spring 2022
Why do we need modulation?
• We need modulation for three main reasons:
2. Simultaneous Transmission of Several Signals:
• To transmit several signals using the same channel without interference,
these signals must occupy separate frequency bands
• This can be achieved by modulating the signals using different carrier
frequencies, so that the modulated carriers occupy separate frequency
bands.
• This can allow many users to share the same channel.
• This is called Multiplexing or Multiple Access.
• In multiplexing, all the signals are modulated, combined and then transmitted
using the same transmitter. This is used in telephony systems.
• In multiple access, the signals are modulated and transmitted using
separate transmitters. The modulated signals are then combined in the
channel. This is the case in radio broadcasting.
Prepared by: Dr. Waleed Tariq Sethi- Ghulam Ishaq
Khan Institute-Spring 2022
Why do we need modulation?
• We need modulation for three main reasons:
3. Obtaining Better Tradeoff between SNR and B:
• Modulation can be used to obtain better SNR at the expense of bandwidth.
• Some types of modulation provide better SNR vs. bandwidth tradeoff.
• More reasons:
– Moving the signal to a better frequency slot (e.g. for lower attenuation or
interference)
– Shifting the signal to a more suitable frequency (e.g. optical range for optical
fibers)
– etc.
 SHANON CAPACITY
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Khan Institute-Spring 2022
Channel Capacity & Data Rate
Nyquist Channel
Prepared by: Dr. Waleed Tariq Sethi- Ghulam Ishaq
Khan Institute-Spring 2022
Assignment # 1
1. On Slide 13, a time line of 1G to 5G is mentioned. Draw a table comparing
these technologies. Select any 5 features to compare the 5 generations.
2. Briefly explain all mentioned emerging technologies in the slide 14 from
a communication theory perspective. (Short explanations and concepts
only!)
3. Explain in detail the key difference between an AM and FM radio from
frequency re-use perspective.
• Note:
1) In handwritten form and to be handed over to TA.
2) All identical submissions will be marked as zero.