Communication

Systems – 1
(22EECC302 &
22EICC312)
 Describe and analyze the generation,
1
detection of AM, FM and PM signals
es
o m
t c Represent signals and types of noise using
ou suitable distribution functions 2
s e
ur
Co 3
Evaluate the performance of various
mod. schemes in the presence of noise.

Demonstrate communication theory

using suitable simulation tool and 4
hardware
Identify the importance of sampling and
5 understand various pulse mod.
techniques
 Text
Books
1. “Communication Systems” by ‘Simon
Haykin’ John Wiley 2003. 5th edition,
2009

2. “Electronic communication systems”,

Kennedy and Davis, TMH, Edn. 6, 2012

3. “Digital communications”, Simon

Haykin, John Wiley, 2006
 Chapter –
1

Analog
Communication
Techniques
 Introduction
Communication means transmission of information from
one place to another.
(or)
Communication refers to the sending, receiving and
processing of information by electronic means.
Sending

Medium

Receiving

Ref: 1. “Communication Systems” by ‘Simon Haykin’ John Wiley 2003. 5th edition,
2009
2. “Electronic communication systems”, Kennedy and Davis, TMH, Edn. 6, 2012
 Communication Timeline

Fire Lighthouse Church Bells Mirrors

Smoke
Beacons Sounds
Courtesy: http://clipart-library.com/

Pegions
Humans Humans Semaphor
 Communication Timeline Contd.

Morse Code
Telegraph Radio Telephone
Courtesy: http://clipart-library.com/

Television – FAX Pager

 Communication Timeline Contd.

Mobile Internet Emails

Phone
Courtesy: http://clipart-library.com/

Smartphones Tablet Laptop

Communication Timeline Contd.

https://www.youtube.com/watch?v
=YrtANPtnhyg

Sixth Sense
Technology
Ref: Analog & Digital Communication by TL Singal
Courtesy: Data Communications and Networking
(Behrouz A. Forouzan)
Courtesy: Data Communications and Networking
(Behrouz A. Forouzan)
Courtesy: Data Communications and Networking
(Behrouz A. Forouzan)
Courtesy: Data Communications and Networking
(Behrouz A. Forouzan)
Courtesy: Data Communications and Networking
(Behrouz A. Forouzan)
 Communication System

Information Up-conversion
Modulation Amplifier
Source & filter

Text
Image Transmitter Channel Noise
Voice/audio
Video

Information Down-conversion
Demodulation Amplifier
retrieved & filter

Receiver
Basic elements of communication system

Transmitter is the equipment which converts physical message,

such as sound, text, pictures etc., into corresponding electrical
signal.

Channel may be either wired or wireless, which provides

transmission path between transmitter and receiver.

Receiver is equipment which converts electrical signal back to the

physical message.
Courtesy: Data Communications and Networking
(Behrouz A. Forouzan)
Courtesy: Data Communications and Networking
(Behrouz A. Forouzan)
Courtesy: Data Communications and Networking
(Behrouz A. Forouzan)
Modulation
 Carrier

Wireless
Channel

Source Destination
Advantages:
 Reduce the height of the transmitting and receiving
antennas
 Increase the communication range
 Allows to send multiple signals (Multiplexing)
 Avoid the mixing of signals
 Improves the signal receiving quality (SNR)
Definition:
The process of varying one or more properties
of a high frequency signal in accordance with
the low frequency signal.

High frequency signal -> Carrier signal

Low frequency signal -> Message signal

Properties of the Amplitude

signal :
Frequency
Phase

Courtesy: Forouzan, A. Behrouz. Data communications & networking.

Tata McGraw-Hill Education.
 High Frequency
Carrier

If the amplitude (Vc) of the carrier signal is varied in

Amplitude proportion to the instantaneous value of the analog
Modulation information signal, by keeping the frequency and phase as
constant, the process is known as Amplitude Modulation
(AM).
If the frequency (fc) of the carrier signal is varied in
Frequency proportion to the instantaneous value of the analog
Modulation information signal, by keeping the amplitude and phase as
constant, the process is known as Frequency Modulation
(FM).
If the phase angle (θ) of the carrier signal is varied in
Phase
Modulation proportion to the instantaneous value of the analog
information signal, by keeping the amplitude and frequency
as constant, the process is known as Phase Modulation
(PM).
Ref: Analog & Digital Communications TL Singal
High Frequency
Carrier

Message signal

AM signal

FM signal

PM signal

https://www.carritech.com/news/what-is-modulation-in-
 Modulation Schemes

Digital message Analog message

signal signal
Digital Analog
ASK
PSK
Continuous Pulsed
FSK
AM PPM
Continuous
carrier PM PAM
wave FM PWM
Continuous Pulsed
carrier carrier
wave wave
 Basic Definitions
An analog signal is a continuously varying electro-
magnetic wave.
Ref: Analog & Digital Communication by TL Singal

A digital signal is a sequence of voltage pulses, having a constant

positive and negative voltage levels (corresponding to binary 0 and
1 respectively).

A baseband signal (also known as modulating signal) is an

information signal generated by the information source or the
input transducer.

A passband signal (also known as bandpass signal or

modulated signal) is the signal produced after performing
modulation.

Modulation is performed at the transmitting end of the
communication system.

At the receiving end of the system, we usually require the
original baseband signal to be restored.

Demodulation is the process by which the baseband signal
is restored at the receiver.
 Modes of Communication
Ref: Analog & Digital Communication by TL Singal

Simplex Full-Duplex
Ex: AM/FM broadcast Ex: Landline telephone
radio, TV broadcast,
Half-Duplex calls, two-way radio,
Cable TV, cellular
Ex: Walkie-talkie radio communication links,
Pagers sets used by police and radar, satellite, data
para-military services communications, LANs
THANK YOU