Ece4710 L1

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ECE 4710 / 7710 Communication Systems Goal : To provide an introduction to digital ccommunication ommunication system basics. Topics include: signal analysis, power spectrum density, baseband digital signaling, signal transmission and filtering, modulated digital communications, error performance, and communication link  analysis.  Instructor : Dr. Curt Davis Office : 323 EBW Phone: 884-3789 Email: DavisCH@m [email protected] issouri.edu Course Time : M W F from 10-11 pm  Course Location : 355 EBW  Course Eligibility : Undergraduate Students: satisfactory completion of ECE 3810. Graduate Students: basic knowledge of probability and linear signals and systems.  Text :  Digital & Analog Communication Systems  –  7 th Edition, Leon Couch, Prentice Hall, 2007. 

ECE 4710: Lecture #1  

ECE 4710 / 7710 Communication Systems Homework : Homework will be assigned approximately once a week and will be due at the beginning of the hour for the class class period one week later. later. Each student is allowed to turn turn in one late homework assignment at 50% credit and this must be turned in no later than 3 PM on the day after the assignment is due. After this no credit will be given for late homewor homework. k. If  you plan to miss a class for any reason, you are responsible for arranging for the homework  to be turned in.  Exams : All exams ar aree mandatory mandatory.. Failure to ta take ke an exam will result in an F for that exam. If for some legitimate reason (sickness, death in the family, etc.) you cannot take an exam on the scheduled day, you must notify me prior to the exam so other arrangements can be made.  Grading : The following perc percentages entages will be used to determ determine ine your final course gr grade: ade: 

Homework First Exam Second Exam Final Exam

15%  25%  30%  30% 

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ECE 4710: Lecture #1

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ECE 4710 / 7710 Communication Systems Grading Scale** :

Grade A B C D F

%  > 90  80-89  70-79  60-69  < 60 

** Grading scale may be adjusted at the end of the semester depending upon class performance and overall distribution of final %’s. Different grading scales may be used for undergraduate and graduate students  based upon class performance. Normally Normally there is no “curve” for graduate students final grading scale.  Academic Dishonesty : Academic honesty is fundamental to the activities and principles principles of a university university.. All members of the academic community must be confident that each  person’s work has been responsibly and

honorably acquired,ordeveloped, and to gain an advantage not academic given to all students as dishonest whether not the effor effort t ispresented. successful.Any Theeffort academic community re regards gards dishonesty aiss an extremely serious matter, matter, with serious consequences that range from proba probation tion to expulsion. When in doubt about plagiarism, paraphrasing, quoting, or collaboration, consult the course instructor. Copying homework assignments (from previous solutions or other people) and cheating on exams will not be tolerated. Any occurrence of this will be deal dealtt with on a case by case basis and may be grounds for dismissal from the class. 

ECE 4710: Lecture #1

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ECE 4710 / 7710 Communication Systems Electronic Notes  A complete set of course notes are available in MS PowerPoint format for the use of the student. The notes ar aree organized by lecture and closely follow th thee lecture #’s #’s identified in the course outline. All 41 lectures are currently aavailable vailable on the website. These are being  provided because this course covers a great deal of material in a short time. Past experience has shown that it is difficult for students to take all the notes and concentrate on the lecture content at the same time. Thus, students are en encouraged couraged to get the the lecture notes prior to coming to class. These should then then be broug brought ht to class sso o that additional comments can be added added to the n notes otes as needed. In addition, the students are encouraged encouraged to bring their course textbook to every class so that they can easily refer to figures and tables that are referenced by the instructor frequently.  A complete set of the homework assignments in MS Word format are also being provided for easy access.  The lecture notes and homework assignments are available at http://bengal.missouri.edu/~davisch/ece4710/ 

ECE 4710: Lecture #1

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ECE 4710 / 7710 Communication Systems Computer Useage  Homework assignments will often require you to use a computer to plot signals, compute spectral responses, evaluate integrals, generate random numbers for probability calculations, and analyze communication communication systems. I strongl strongly y encourage students in this course to use either Matlab or Mathcad for homework problems that require this type of  analysis. Student versions versions of these software programs are available at very reaso reasonable nable  prices. Computer Spectrum in Brady Commons carries the student version of Mathcad for  $125. The Matlab student version version can be pur purchased chased online about about $100 (credit card only) only) at:  http://www.mathworks.com/products/education/student_version/sc/ Computer Spectrum should also be able to order this from MathWorks (company who makes Matlab) as well, but they do not currently keep it in stock. 

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ECE 4710: Lecture #1  

ECE 4710 / 7710 Communication Systems Computer Useage For those of you who do not have a home computer and/or do not want to purchase the software, Matlab is available in the ECN computer lab (W2003 EBE).  Your  textbook’s author has provided a set of Matlab (*.M) and Matchad (*.MCD)  programs for solving selected equations and example/study problems throughout the textbook (See Section 1-5 on pg. 7 of textbook). The selected eq equations/problems uations/problems that that have the computer programs are denoted by a computer symbol : . The *.M and *.MCD files are available on my website in the “\Matlab” or “\Matchad” subdirectories. They are also available at the following web-site: http://www.couch.ece.ufl.edu

See Appendix C for Quick Start for Running M files Programming in Matlab   “







and

ECE 4710: Lecture #1

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ECE 4710 / 7710 Communication Systems Lecture #

Day of Week

Date

Book Sections

Topic

1 2 3 4 5

M W F M W

Aug 20 Aug 22 Aug 24 Aug 27 Aug 29

Chpt. 1 (1-6) Chpt. 1 (7-11) Chpt. 2 (1) Chpt. 2 (2-3) Chpt. 2 (6)

Introduction Information & Channel Capacity Signal Properties Fourier Transform & PSD Linear Systems Review

6 -7 8 9 10 11

F M W F M W F

Aug. 31 Sep 3 Sep 5 Sep 7 Sep 10 Sep 12 Sep 14

Chpt. 2 (7,9) -Chpt. 3 (1-2) Chpt. 3 (3) Chpt. 3 (3) Chpt. 3 (4) Chpt. 3 (5)

Bandlimited Signals & Noise Labor Day Holiday Pulse Amplitude Modulation (PAM) Pulse Code Modulation (PCM) Pulse Code Modulation (PCM) Digital Signaling Line Codes & Spectra

12 13 14 --15 16 17

M W F M W F M

Sep 17 Sep 19 Sep 21 Sep 24 Sep 26 Sep 28 Oct 1

Chpt. 3 (5) Chpt. 3 (5) Chpt. 3 (6) --Chpt. 4 (1-2) Chpt. 4 (3-4, 6-8) Chpt. 4 (16)

18

W

Oct 3

Chpt. 4 (16)

Line Codes & Spectra Synchronization Intersymbol Interference First Exam Modulated Signals Bandpass Spectrum & Power  Tx’s & Rx’s  Rx’s

 

ECE 4710: Lecture #1

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Communication Systems 

Designed to transmit information between two points



Electrical systems do this via electrical signals 

Time-varying voltage in electrical circuit » “Wired” communic communication ation  



Time-varying EM wave propagating through air/space » “Wireless” communica communication tion  



Transmission of information implies that message is not known ahead of time  random 

Randomness (entropy) is proportional to information content

ECE 4710: Lecture #1

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Communication Systems 

Design and selection of information bearing waveforms is critical to successful communication



Waveform design/selection depends on: 

Signal Bandwidth



Information Data Rate



Transmission Transmissi on Center Frequency

 

Signal Power/Energy Resistance to Noise/Interferenc Noise/Interference e



Complexity/Cost to Design Tx/Rx Circuits

ECE 4710: Lecture #1  

Communication History Year

Event

Inventor/Comment

1837

Samuel Morse

1864

Telegr elegraph aph EM Theory

1876

Telephon elephonee

A.G. Bell

1901

Radio Transmiss Transmission ion

G. Marconi

1921

Mobile Radio

1928

Televi elevision sion

P.T. Farnsworth Farnswort h

1933

Frequency Modulation (FM)

E.H. Armstrong

1945 1948

First Computer Information Theory

Univ. of Penn. Claude Shannon

1948

Transistor

Shockley et al.

1950

Error Coding

Hamming

James Maxell

11

ECE 4710: Lecture #1  

Communication History Year

Event

Inventor/Comment

1958

Integrated Circuit

Jack Kilby (TI)

1965

Satellite Communications

1971

Microprocessor 

Intel

1972

Cellular Radio Concept

Motorola/Bell Labs

1981

Personal Computer

IBM

1983

1st Generation (1G) Cellular

Analog AMPS

1989

GPS Satellites

U.S. Military

1991

2G Digital Cellular

GSM in Europe

1995

WWW and Interne Internett

1998

2G CDMA Cellular

Qualcomm/Sprint PCS

2003

3G Cellular Standards

Whole World

12

ECE 4710: Lecture #1  

 Analog vs. vs. Digital 

Information Source   Analog:

continuous range of states continuous states

» Microphone: output output voltage signal with with continuous continuous 

range of amplitudes Digital: finite set of possible states » Computer Keyboard: Keyboard: finite finite set of characters characters



Waveform = signal voltage vs. time   Analog  continuous amplitude   

Digital  discrete set of amplitudes  

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ECE 4710: Lecture #1  

Digital Communication System 

Typically uses BOTH analog AND digital waveforms   Analog:

carrier waveform (sinusoid) carrier (sinusoid) for transmission transmission

Digital: discrete values for amplitude, frequency, or phase



used to represent information bits 

Binary Digital Waveform 2 states for each digital symbol, e.g. 0, 1



0

1

0

1

0

1

0

1

-ary Digital Waveform -ary

  M 

  M -states -states

for each symbol

00

01 00

10 00 11

00 01

 M  = 4 states  2 bits/symbol



# Bits/Symbol = log

2

 M ) ( M 

ECE 4710: Lecture #1

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Deterministic vs. Random 

Waveform Classification 

Deterministic: waveform modeled or represented completely as a function of time, e.g. s (t ) = A cos (w  t + f ) Random/Stochastic: cannot be completely specified as a function of  time  





Recall that randomness = information 

Waveforms must be random to carry significant information

Source/Information Waveform: each symbol can be deterministic but information stream is random  Noise is also a random signal  Probability/Statistics must be used to analyze 

performance of any communication system

ECE 4710: Lecture #1

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Digital Communication System 

Digital communication systems have MANY MANY   advantages over analog systems including: 

Data encryption for security/priv security/privacy acy



Combine multiple information types (voice, video, data) on a single transmission channel



Resistant to noise, fading, and interference » Small error probability probability even even with large large interference



Error detection and correction using digital codes



Implementation using all digital circuits

ECE 4710: Lecture #1

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Basic Communication System Information Source

Transmission Channel

Baseband Signal Processing

m (t)  

r  (t)

 s (t)

m (t)

Information Sink

˜

Noise Modulation & Carrier  Circuits

Transmitter Tran smitter (Tx)

n (t)

Demodulation & Carrier  Circuits

Baseband Signal Processing

Receiver (Rx)

Goal: Design system to transmit information, m(t ), with as little deterioration as possible within design constraints of  signal power, signal bandwidth, and system cost

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System Components 



Baseband signals  signal centered at  f  = 0 

m(t) : input information signal (voice, data, video, etc.)



m(t)   : received information signal distorted/corrupted by noise, interference, non-linearities, etc. ˜

Baseband Signal Processing 

Encoding of information  “Source coding”  coding” 



Filtering to minimize signal bandwidth



Error coding to protect information

 “Channel Coding”  Coding” 



ECE 4710: Lecture #1

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System Components 

Tx Carrier Circuit 

Converts processed baseband signal into frequency band that is appropriate for transmission thru channel



Tx output  s(t) is called a “bandpass” signal  signal 

» Car Carrie rierr fre freque quency ncy,, f c, is center frequency of bandpass signal





m(t)   s(t) s(t) conversion or mapping is called “modulation”  “modulation” 

Channel : Two major categories 

Wire



Wireless



Introduces significant distortion and impairments



coaxial, twisted pair, & fiber optic cables 

mobile radio, broadcast, satellite channels

ECE 4710: Lecture #1

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System Components 

Channel Impairments   Attenuation,

multipath echoes, multipath echoes, fading, noise, noise, interference,

etc. 

Channel characteristics characteristics can be fairly stable (wired) or  change rapidly as function of time (mobile radio) » Time-varying channel is is difficult difficult to model



Noise » Man-made: computers, computers, motors, motors, car ignition, ignition, other users (cellular phone) » Natural: thermal “background” noise, lightening, etc.  etc.  

ECE 4710: Lecture #1

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System Components 

Receiver Carrier Circuit (Rx) 



Takes corrupted signal from channel and converts down to baseband signal  demodulation (mod/dem = modem)

Rx Baseband Signal Processing 

Cleans up distorted baseband signal and delivers estimate of the source information signal  m(t)    ˜





Filtering, bit detection, error detection/correction

Performance measures   Analog  

 N ) ratio output signal-to-noise (S / N 

Digital  probability of bit error or “Bit Error Rate (BER)”  (BER)” 

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