1. EE521 Analog and Digital Communications
Today some topics will be presented on the whiteboard. The slides will be updated on the web site in a few days.
EE521 Analog and Digital Communications
James K. Beard, Ph. D.
Tuesday, February 1, 2005
11/30/2018
Week 2

2. Essentials Text: Bernard Sklar, Digital Communications, Second Edition
Prerequisites
Consent of Instructor (Dr. Silage)
SystemView (CD-ROM with text)
Office
E&A 709
Hours TBA, Tuesday afternoons planned
MWF 10:30 AM to 11:30 AM added
11/30/2018
Week 2

3. Today’s Topics SystemView Signals and Noise
Detection of Binary Signals
Inter-symbol interference
Equalization
Discussion (as time permits)
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4. Homework Problem Sklar Problem 2.4 Page 101
Given in the files from the CD-ROM
Basis of analysis is Fourier series
Infinite series of pulses in time domain is infinite series of pulses in frequency domain (text section pp 63-66)
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5. Sklar’s Answer Solution is given as SystemView file Sum_of_cosines.svu
Number of tokens>10 puts Student version in no-save mode
Fourier transform of train is (Sklar, equations (2.5), (2.6), (2.8)
The issue is that the aux files problem 2.4 appear not to be related to the
textbook problem 2.4.
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6. The Homework Problem Basis is Principle Block diagram of Figure 2.1
Natural sampling, pp
As opposed to impulse sampling,
Principle
Sampling replicates system spectra
Distance between replicated spectra is the signal bandwidth
Block diagram of Figure 2.1
Mixes one of these replicated spectra to baseband
Low pass filters to recover the signal
Problem_2_4.svu
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Week 2

7. Formatting and Baseband Modulation
Topics from Text Chapter 2
2.5, Sources of Corruption
2.6, Pulse Code Modulation
2.7, Uniform and Non-uniform Quantization
2.8, Baseband Modulation
Corruption: noise, fading, interference
PCM: Simple digital modulation
Quantization: the ADC and data compression
Baseband modulation: synthesizing the signal
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8. Sklar Chapter 2 Legend: From other sources Essential Information
Message symbols
Optional
Channel symbols
X M I T
Format
Source encode
Encrypt
Channel encode
Multi-plex
Pulse modulate
Bandpass modulate
Freq-uency spread
Multiple access
Digital input
Channel impulse response
Bit stream
Synch-ronization
Digital baseband waveform
Digital bandpass waveform
Channel
Digital output
R C V
Format
Source decode
Decrypt
Channel decode
Demul-tiplex
Detect
Demod-ulate & Sample
Freq-uency despread
Multiple access
To other destinations
Channel symbols
Information
sink
Message symbols
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9. Spectral Attributes We are looking for better bandwidth efficiency
Obtained by modulations with
More compact spectra
Less interference between symbols
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10. M-ary Pulse Modulation
Base modulation types
Pulse Amplitude Modulation (PAM)
Pulse Position Modulation (PPM)
Pulse Duration Modulation (PDM)
Number of different pulse shapes in a character is M, hence M-ary modulation
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11. Baseband Demodulation and Detection
Signals and noise
Detection of binary signals in Gaussian noise
Inter-symbol interferencie
Equalization
11/30/2018
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12. Signals and Noise Base problem is symbol error
Additive noise can bridge the difference between waveforms for different symbols
Symbol error rate is function of
SNR
Modulation type
Basic figure of merit is bit energy divided by noise power spectral density
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13. Summary
Course overview: we will learn how to implement critical technologies for digital communications
Course is integrated with a follow-on next semester
Baseband signals are where we do modulation == formatting for the channel
SystemView lets us have most of the benefits of a lab with minimum time
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14. Feedback Around the room Please let me know What your background is
Design
SystemView
Communications
What you expect from this course
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15. Text and Assignment Text Assignment: Read Text
Benard Sklar, Digital Communicatinons ISBN
SystemView User's Manual, Elanix, Inc
Assignment: Read Text
Chapter 3, 3.1, 3.2, 3.3, 3.4
Load SystemView and examine the samples and demos
Browse appendices of text for review and supplementary material
Look at TUARC
K3TU, websites
11/30/2018
Week 2