Transcript الشريحة 1 - جامعة فلسطين

Palestine University
Faculty of Information Technology
IGGC2204 - Understanding Telecommunications
Instructor: Dr. Eng. Mohammed Alhanjouri
1st Lecture: Overview
Palestine University
Faculty of Information Technology
Syllabus
(IGGC2204)
Understanding Telecommunications
Instructor Information
 Name of Instructor: Dr. Eng. Mohammed Alhanjouri
 Location: Faculty of Engineering (Software Engineering Dept.)
 E.mail: [email protected] or [email protected]
 Class Time: Sat (8:00-9:30)am and Mon (8:00-9:30)am
Course Objectives
To provide the students with the basics of
communication systems. Upon completion of this course, the
students should be able to:
 To understand communication systems
 To understand the frequency domain and the bandwidth
concept.
To understand the Fourier series and Fourier Transform.
 To understand properties of Fourier Transform and the
conversion between time and frequency domain.
 To understand the types of amplitude modulation (AM)
 To understand the Frequency modulation (FM)
 To be able to select appropriate modulation techniques for
our Applications
Course Textbook(s)
B. P. Lathi, "Modern Digital and Analog
Communication Systems", Third edition, Oxford
University Press, 1998.
Simon Haykin, "Communication Systems", Fourth
Edition, John Wiley & Sons, 2001.
Other Recommended Resources:
A. Bruce Carlson, "Communication Systems",
Third Edition, McGraw Hill, 1986.
Course Grades:
Students grades are calculated according to their
performance in the following course work:
Assignments Quizzes Midterm
Exam
10%
10%
30%
Final
Exam
45%
Attendance
5%
One week for each Assignment
No assignments will be accepted beyond the due date.
Date
Topic
Readings
1st week
Introduction to Communication Systems
Ch1
2nd week
Introduction to Signals
2.1  2.4
3rd week
Introduction to Signals
2.5  2.7
4th week
Fourier Series
2.8  2.10
5th week
Fourier Transform
3.1  3.3
6th week
Properties of Fourier transform
Ch 2 2nd textbook
7th week
Ideal and Practical Filters
3.5
8th week
Midterm Exam
All above chapters
9th week
Amplitude Modulation
4.1  4.4
10th week
Single and Vestigial Sideband AM
4.5, 4.6
11th week
Superheterodyne AM Receiver
4.8
12th week
Frequency and Phase Modulations
5.1, 5.2
13th week
Generation of FM Waves
5.3
14th week
Demodulation and receiving of FM
5.4, 5.6
15th week
Revision
All above chapters
16th week
Final Exam
All above chapters
CH1: Introduction to Communication Systems
The study of communication systems can be divided into
two distinct areas:
1. How communication systems work.
2. How they perform in the presence of noise.
The study of each of these two areas, in turn, requires
specific tools. To study the first area, the students must be
familiar with signal analysis (Fourier techniques), and to
study the second area, a basic understanding of probability
theory and random processes is essential.
This course examines communication by electrical signals.
In the past, messages have been carried by runners, carrier
pigeons, drum beats, and torches.
A short History of Telecommunications:
 Thousands of years before the Common Era (B.C.E.)
drums were used to send out messages.
 The fall of Trojan was achieved by signals of torches in
1100 B.C.
 490 B.C. a runner delivered message from marathon to
athens (he broke down and died). Also Alexander the Great ,
Hannibal and Caesar used running carriers to transmit their
commends
 150 A.D. the roman used smoke signals to spread the
message (about 4.500 Km).
 1100 Genghis Khan spread the reports of his victories
using carrier pigeons.
 1600 the British Admiral Sir William Penn developed a
comm. Code using flag or light.
 1835 Samuel Morse developed his code ( points and
dashes). The first long distance message was sent from
Baltimore to Washington in 1843.
 1876 Alexander Graham Bell applies for a patent with his
telephone in March 1876. only 3 hours later Elisha Gray
submitted an application for the same device
 1861 Maxwell at king’s college in London proposed
mathematical theory of EM waves
 1887 Hertz demonstrated the existence of EM waves
 1895-1898 Marconi built radio telegraph, his signal
bridged the English channel (52km wide)
 1921 First analog land mobile by police department in
Detroit and London, respectively.
 1933 FM was invented which made possible high quality
radio comm.
 1947 Improved mobile telephone service (IMTS) using
FM was developed by AT&T. the 1st mobile system
connected to PSTN Bell labs.
 1948 extending number of users in cellular concept
during and after WW2
 Second Generation1990’s Cellular has enjoyed
exponential growth since 1988, with over 200 million users
worldwide today ..
 1990 Global System Mobile (GSM) is introduced in
800-900 MHz band.
2.5 Generation- :1998 mobile wireless data: I-mode, a
wireless data service and internet “micro-browser” is
introduced.
 3rd Generation- 2000: IMT-2000 (International Mobile
Telecom.) proposals for a world-wide 3rd generation
standard are submitted.
 2??? 4th generation – may be to use W-CDMA-2000 or
OFDM (orthogonal frequency division multiplexer)
TV, Satellite, LAN, and 100 Mbps bandwidth
Introduction
 The purpose of Comm. System is to transport an
information signal from a source to a user destination
via a comm. channel (transmission system).
 A comm. system is of an analog or digital type
 In an analog comm. system, the information signal
is continuously varying in both amplitude and time,
while for digital comm. system, the information
signal is processed so that it can be represented by a
sequence of discrete message.
Communication Model
Transmitter
Information
Source
Destination
(User)
Source
Transducer
Channel
Encoder
Noise,
Interference and
distortion
Comm.
Channel
User
Transducer
Channel
Decoder
Receiver
Communication Model (Cont.)
 Information source: generates the data to be
transmitted. Examples are telephones and computers
 Transmitter: transforms and encodes the
information in such a way as to produce
electromagnetic signals that can be transmitted across
some sort of transmission system (comm. Channel).
For example, a MODEM takes a digital bit stream
from a personal computer and convert it to analog
signal that can be transmitted by the telephone
networks
Communication Model (Cont.)
 Transmission system (Comm. channel): this can
be a single transmission line or complex network
connecting source and destination (wire, Coaxial
cable, optical fiber, or radio link)
 Receiver: accepts the signal from the transmission
system and converts it into a form that can be
handled by the destination device like as the MODEM
 Destination: takes the incoming data from the
receiver.
 For Example: the workstation can be connected
to the server by the following communication system
 
workstation
 
MODEM
MODEM
Server
Public telephone
network
Information
source
Receiver
Transmitter
Transmission system
(Comm. channel)
destination
 The comm. Channel contents the noise that classified
as:
 External noise includes interference, human-made
noise, fluorescent lights, or natural noise (electrical
storms, solar, and intergalacitic radiation). With proper
care, this noise can be minimized or eliminated)
 Internal noise results from thermal motion of electrons
in conductors, random emission, diffusion or
recombination of charged carriers in electronics devices.
Proper care can reduce the effect of this noise but can
never eliminate it
ANALOG AND DIGITAL MESSAGES
Messages are digital or analog. Digital messages are
constructed with a finite number of symbols. For example,
printed language consists of 26 letters, 10 numbers, a
space. Thus, a text is a digital message constructed from
about 50 symbols. Human speech is also a digital
message, because it is made up from a finite vocabulary in
a 1anguage. Similarly, a Morse-coded telegraph message
is a digital message constructed from a set of only two
symbols-mark and space. It is therefore a binary message,
implying only two symbols. A digital message constructed
with M symbols is called an M-ary message.
Analog messages, on the other hand, are characterized by
data whose values vary over a continuous range. For
example, the temperature or the atmospheric pressure
MODULATION
Baseband signals produced by various information sources are not
always suitable for direct transmission over a given channel. These
signals are usually further modified to facilitate transmission. This
conversion process is known as modulation. In this process, the
baseband signal is used to modify some parameter of a highfrequency carrier signal. A carrier is a sinusoid of high frequency,
and one of its parameters-such as amplitude, frequency, or phaseis varied in proportion to the baseband signal m(t). we have
amplitude modulation (AM), frequency modulation (FM), or
phase modulation (PM).
The Figure shows a baseband signal m(t) and the corresponding
AM and FM waveforms. In AM, the carrier amplitude varies in
proportion to m(t), and in FM, the carrier frequency varies in
proportion m(t) . At the receiver, the modulated signal must pass
through a reverse process called demodulation in order to
reconstruct the baseband signal.
Definitions:
 SNR is defined as the ratio of signal power to
noise power
The bandwidth of a channel is the range of
frequencies that it can transmit with reasonable
fidelity. For example, if a channel can transmit
with reasonable fidelity a signal whose frequency
components occupy a range from 0 (dc) up to a
maximum of 5000 Hz (5 kHz), the channel
bandwidth B is 5 kHz.