Selin Aviyente
Assistant Professor
ECE
ECE 457 Spring 2005 Page 1

• Class Web Page: http://www.egr.msu.edu/~aviyente/ECE
457-05.htm
• Lectures: M, W, F 10:20-11:10 a.m. 221
Natural Resources Building
• Office Hours: W 11:30- 1:00 pm, Th 9:30-
11:00 am or by e-mail appointment (2210
EB)
• Textbook: Principles of Communications,
Rodger E. Zimmer and William H. Tranter,
John Wiley, 5th Edition, 2002.
ECE 457 Spring 2005 Page 2

• ECE 458 is designed to complement this course.
• ECE 458 focuses on providing practical experience.
• You will learn material in ECE 457 that is not covered in ECE 458 and vice versa.
• No labs this week.
• There is no lab manual this year, everything will be online.
ECE 457 Spring 2005 Page 3

• 2 Midterm Exams (50%)
– February 25, April 8 in class
• Final Exam, May 3 (30%)
• Weekly HW assignments (10%)
– Will include MATLAB assignments
– HWs should be your own work (no copying!)
– Assigned on Fridays due next Friday (except during exam weeks)
– No late HWs will be accepted.
• Quizzes (10%)
– They will be unannounced.
– Based on HW questions (10-15 minutes long)
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• Cheating in any form will not be tolerated.
This includes copying HWs, cheating on exams and quizzes.
• You are allowed to discuss the HW questions with your friends, and me.
• However, you have to write up the homework on your own.
• There is no make-up for missed quizzes.
• If you have an excuse for not being in class, please e-mail me before class.
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• Honor credit option is available
• Typical projects have either a software/hardware implementation component and an oral presentation.
• Past projects include:
– Building a FM transmitter
– MATLAB simulation of digital modulation systems.
• Please feel free to come and talk to me about your ideas for a possible project.
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• Overview of Communication Systems
• Review of Signal Analysis (ECE 366)
• Deterministic Modulation
– Linear (DSB,AM,SSB,VSB)
– Angle Modulation (FM, PM)
• Review of Probability and Random
Processes
• Noise in Modulation Systems
• Digital Modulation (as time permits)
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• A communication system conveys information from its source to a destination.
• Examples:
– Telephone
– TV
– Radio
– Cell phone
– PDA
– Satellite
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• A communication system is composed of the following:
Source
Channel Receiver
Output
Transducer
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• Source: Analog or digital
• Example: Speech, music, written text
• Input Transducer: Converts the message produced by a source to a form suitable for the communication system.
• Example:
Speech waves  Microphone  Voltage
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• Couple the message to the channel
• Operations: Amplification, Modulation
• Modulation encodes message into amplitude, phase or frequency of carrier signal (AM, PM, FM)
• Advantages:
– Reduce noise and interference
– Multiplexing
– Channel Assignment
• Examples: TV station, radio station, web server
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• Physical medium that does the transmission
• Examples: Air, wires, coaxial cable, radio wave, laser beam, fiber optic cable
• Every channel introduces some amount of distortion, noise and interference
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• Extracts message from the received signal
• Operations: Amplification, Demodulation,
Filtering
• Goal: The receiver output is a scaled, possibly delayed version of the message signal (ideal transmission)
• Examples: TV set, radio, web client
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• Converts electrical signal into the form desired by the system
• Examples: Loudspeakers, PC
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• The most important question for a communication channel is the maximum rate at which it can transfer information.
• There is a theoretical maximum rate at which information passes error free over the channel, called the channel capacity C.
• The famous Hartley-Shannon Law states that the channel capacity C is given by:
C=B*log(1+(S/N)) b/s where B is the bandwidth, S/N is the signal-to-noise ratio.
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• Therefore, there are two factors that determine the capacity of a channel:
– Bandwidth
– Noise
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• Most precious resource in communications is “frequency spectrum”
• The “frequency spectrum” has to be shared by a large number of users and applications:
• AM Radio, FM Radio, TV, cellular telephony, wireless local-area-networks, satellite, air traffic control
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• The frequency spectrum has to be managed for a particular physical medium
• The spectrum for “over-the-air” communications is allocated by international communications organization
• International Telecommunications Union
(ITU)
• Federal Communications Commission (FCC) designates and licenses frequency bands in the US.
ECE 457 Spring 2005 Page 18

Application
AM Radio
TV (Channels 2-
6)
FM Radio
TV (Channels 7-
13)
Cellular mobile radio
Frequency Band
0.54-1.6 MHz
54-88 MHz
88-108 MHz
174-216 MHz
806-901 MHz
ECE 457 Spring 2005 Page 19

• Internal and External Noise
• Internal Noise: Generated by components within a communication system (thermal noise)
• External Noise:
– Atmospheric noise (electrical discharges)
– Man-made noise (ignition noise)
– Interference (multiple transmission paths)
ECE 457 Spring 2005 Page 20

Year Event
1838
1876
Telegraphy
(Morse)
Telephone (Bell)
1902
1933
1936
1953
Radio transmission
(Marconi)
FM radio
TV broadcasting
Color TV
ECE 457 Spring 2005 Page 21

Year
1962
1972
1985
1990s
Event
Satellite communication
Cellular phone
Fax machines
GPS, HDTV, handheld computers
ECE 457 Spring 2005 Page 22