Instructor s Manual to accompany

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1 Instructor s Manual to accompany MODERN ELECTRONIC COMMUNICATION Ninth Edition Jeffrey S. Beasley Gary M. Miller Upper Saddle River, New Jersey Columbus, Ohio

Copyright 2008 by Pearson Education, Inc., Upper Saddle River, New Jersey 07458. Pearson Prentice Hall. All rights reserved. Printed in the United States of America.

2 Copyright 2008 by Pearson Education, Inc., Upper Saddle River, New Jersey Pearson Prentice Hall. All rights reserved. Printed in the United States of America. This publication is protected by Copyright and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or likewise. For information regarding permission(s), write to: Rights and Permissions Department. Pearson Prentice Hall is a trademark of Pearson Education, Inc. Pearson is a registered trademark of Pearson plc Prentice Hall is a registered trademark of Pearson Education, Inc. Instructors of classes using Beasley/Miller, Modern Electronic Communication, Ninth Edition, may reproduce material from the solutions manual for classroom use ISBN-13: ISBN-10:

3 Instructor s Manual to Accompany MODERN ELECTRONIC COMMUNICATION / 9e Chapter Overviews Test Item File Answers to Chapter Problems Troubleshooting with Electronics Workbench - Solutions Laboratory Manual Experiment Results Electronic Workbench Multisim - Solutions Jeffrey S. Beasley and Gary M. Miller

4 CONTENTS Part I: Chapter Overviews Chapter 1: Introductory Topics 1 Chapter 2: Amplitude Modulation: Transmission 4 Chapter 3: Amplitude Modulation: Reception 7 Chapter 4: Single-Sideband Communication 10 Chapter 5: Frequency Modulation: Transmission 12 Chapter 6: Frequency Modulation: Reception 15 Chapter 7: Communications Techniques 17 Chapter 8: Digital Communication: Coding Techniques 19 Chapter 9: Wired Digital Communication 21 Chapter 10: Wireless Digital Communications 23 Chapter 11: Network Communications 25 Chapter 12: Transmission Lines 28 Chapter 13: Wave Propagation 30 Chapter 14: Antennas 32 Chapter 15: Waveguides and Radar 34 Chapter 16: Microwaves and Lasers 37 Chapter 17: Television 39 Chapter 18: Fiber Optics 42 Part II: Test Item File Chapter 1 44 Chapter 2 53 Chapter 3 64 Chapter 4 78 Chapter 5 91 Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter i

5 Part III: Answers to Chapter Problems Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter Chapter PART IV: Troubleshooting with EWB Multisim - Solutions Chapter 1: Understanding the Frequency Spectra 324 Chapter 2: AM Measurements 324 Chapter 3: AM Demodulation 325 Chapter 4: Single-Sideband Generation 325 Chapter 5: Generating and Analyzing the FM Signal 326 Chapter 6: FM Receiver Blocks 326 Chapter 7: Mixer and Squelch Circuits 327 Chapter 8: Sampling the Audio Signal 327 Chapter 9: Sequence Detector 328 Chapter 10: BPSK Transmit-Receive Circuit 328 Chapter 11: Audio Signal Measurements 329 Chapter 12: Network Analyzer 329 Chapter 13: Crystals and Crystal Oscillators 330 Chapter 14: Dipole Antenna Simulation and Measurements 330 Chapter 15: Lossy Transmission Lines and Low-Loss Waveguide 331 Chapter 16: Characteristics of High-Frequency Devices 331 Chapter 17: The Television RF Spectrum 332 Chapter 18: Light Budget Simulation 332 ii

6 Part V: Laboratory Manual Experiment Results 1 Active Filter Networks Frequency Spectra of Popular Waveforms Tuned Amplifiers and Frequency Multiplication Low-Pass Impedance Transformation Networks Phase-Shift Oscillator LC Feedback Oscillator Colpitts RF Oscillator Design Hartley RF Oscillator Design Swept-Frequency Measurements Nonlinear Mixing Principles AM Modulation Using an Operational Transconductance Amplifier RF Mixers and Superhetereodyne Receivers Cascode Amplifiers Sideband Modulation and Detection Frequency Modulation: Spectral Analysis Phase-Locked Loops: Static and Dynamic Behavior FM Detection and Frequency Synthesis Using PLLs Pulse Amplitude Modulation and Time Division Multiplexing Pulse Width Modulation and Detection Digital Communication Link Using Delta Modulation Codecs Electronics Workbench Multisim - db Measurements in Communications Electronics Workbench Multisim Smith Chart Measurements 449 Using the EWB Network Analyzer 24 Tone Decoder Using a Spectrum Analyzer Using Capacitors for Impedance Matching Electronics Workbench Multisim Impedance Matching AM Generation Using an Electronic Attenuator Generating FM from a VCO Upconversion and Downconversion 461 iii

7 Part VI Electronics Workbench Multisim EWB Complementary Exercises Experiment 1 EWB 462 Simulation of an ACTIVE FILTER NETWORKS Experiment 2 EWB 464 USING THE SPECTRUM ANALYZER and the SIMULATION and ANALYSIS of COMPLEX WAVEFORMS Experiment 3 EWB 467 Simulation of Class C Amplifiers and Frequency Multipliers Experiment 5 EWB 469 Simulation of a Phase-Shift Oscillator Experiment 6 EWB 471 Simulation of an LC Feedback Oscillator Experiment 11 EWB 473 Percentage of Modulation Measurement of an Amplitude Modulated Waveform Notes to the Instructor 474 iv

8 OVERVIEW CHAPTER 1 INTRODUCTORY TOPICS 1-1 INTRODUCTION Following a brief introduction to the field of electronic communications, the concept of modulation is introduced. At this early stage very basic words such as a carrier carrying the information are used. Equation 1-1 shows the three characteristics of a carrier that could be modified to carry the information include the amplitude, frequency, and phase. These concepts form the basis for Chapters 2-6. Table 1-1 describes the sub-divisions within the radio-frequency spectrum and Fig. 1-1 presents a simple communication system in block diagram form. A discussion of it should get your students thinking and whet their appetite for the chapters that follow. 1-2 The db in COMMUNICATIONS The db (decibel) is an extremely important measure in communications. Decibels are used to specify measured and calculated values in communications system measurements. The equations for calculating db using power and voltage ratios are provided in equations 1-2 and 1-3. Examples 1-1 to 1-3 demonstrate the method for calculating and converting db values. Another technique for converting many common db values is provided in Table 1-2. Tables and computer programs are often used on the job for performing most db calculations or conversions. A list of common decibel terms is provided in Table NOISE A fundamental limitation in communication systems is noise. This, of course, is due to the fact that the signal picked up by the receiver is very small. Separating it from all the various sources of noise is a critical task. The various types of external noise (man-made, atmospheric, and space) and internal noise (thermal, transistor, and flicker) are described. The calculations associated with thermal and noise voltage are facilitated with Examples 1-4 and NOISE DESIGNATION AND CALCULATION The important concept of signal-to-noise ratio is introduced as a simple ratio (Eq. 1-12) and in decibel form (Eq. 1-13). This is followed by defining the noise figure as the ratio of S/N at the input over the S/N at the output. Some practice on the related calculations is provided in Example 1-6. The concepts of reactance noise effects, noise due to amplifiers in cascade, equivalent noise temperature, and equivalent noise resistance close out this section. The importance of related calculations is indicated by the many examples provided to help your students master these topics. 1-5 NOISE MEASUREMENT The use of a diode noise generator to make some basic noise measurements is introduced. A simple yet effective measurement technique using the diode noise generator is illustrated in Example A quick and useful measurement technique using a basic dual-trace oscilloscope is detailed in Fig It is termed the tangential noise measurement technique. 1

9 1-6 INFORMATION AND BANDWIDTH There are two fundamental limitations on the performance of a communication system. Besides the noise effects just introduced, the bandwidth allocated for transmission is the other basic limitation. Hartley s law states that the amount of information that can be transmitted is proportional to the bandwidth times the time of transmission. To help the student understand the bandwidth that various signals occupy, an introduction to understanding the frequency spectra is provided. This basically non-mathematical approach promotes understanding of a signal s sinusoidal harmonics and how they combine to form complex signals. The square wave waveform analysis in Fig. 1-9 and 1-10 provides graphic illustration of this process. Visual examples of the frequency components making up complex waveforms are provided in Figures 1-11 and These are the FFT representations for a sine wave and a square wave. Table 1-4 gives Fourier expressions for some common periodic waveforms. Figure 1-13 demonstrates the effect a bandwidth-limited signal has on a square wave. 1-7 LC CIRCUITS Sections 1-7 and 1-8 cover some basic characteristics of LC circuits and oscillators. If your students have a good background to this from previous studies, you may wish to omit them. The characteristics of inductors and capacitors are introduced including the concepts of quality (Q) and dissipation (D) factors. This is followed by the concept of resonance and bandpass filters. Examples 1-13 and 1-14 provide practice calculating bandwidth, Q, required component values, and resonant frequencies. 1-8 OSCILLATORS Oscillators are key elements in communication systems. The concept of creating a sine wave via the flywheel effect is introduced with the help of Fig An analysis of some common LC oscillators follows including the Hartley, Colpitts, and Clapp oscillators. The very important crystal oscillator is then detailed. Table 1-5 provides stability and cost information for four different crystal oscillator configurations. A useful crystal test circuit is shown in Fig TROUBLESHOOTING All chapters of this text are concluded with a troubleshooting section. The importance of developing good troubleshooting skills cannot be over-emphasized. Employers and accrediting agencies are in strong agreement on this matter. Each one of these sections provides troubleshooting skills related to the chapter s topics. Often some general troubleshooting techniques are also included as is the case with this section. This section opens with a comprehensive overview of troubleshooting. This is followed by detail on the four types of circuit failures. Detail on the four basic troubleshooting techniques (symptoms, signal tracing and injection, voltage and resistance measurements, and substitution) concludes the general troubleshooting material. Testing a crystal with the aid of the block diagram in Fig is discussed. This section is concluded with information on testing the inductors and capacitors in a Clapp oscillator. A section on understanding digital sampling oscilloscope waveforms is also included in this section. This section discusses the importance of selecting the sample frequency and the effect an improperly selected sample frequency has on the displayed waveform. 2

10 1-10 TROUBLESHOOTING WITH ELECTRONICS WORKBENCH MULTISIM Representative computer simulations using Electronics Workbench (EWB) Multisim are provided in each chapter in this text. The computer files are provided in the CD-ROM which comes with the text. The use of virtual instruments is incorporated into each chapter s presentation on using EWB Multisim. Detailed steps are used in the text to lead the student through each of the virtual experiments. In Chapter 1, the oscilloscope and the spectrum analyzer virtual instruments are used to examine the properties of a square wave. The performance and operation of these virtual instruments closely resemble real test equipment and the user has the ability to make connections and adjustments comparable to that made on equipment when working on a bench. Three EWB exercises are included to further develop the student s understanding of the simulation tool and the virtual instruments. The files provided in the text s CDROM support both the newer Multisim 9 (.ms9), Multisim 7 (.ms7) and Multisim 6 (.msm) formats. The files are located in the ms9, ms7 or msm folders in each respective chapter. 3

11 OVERVIEW CHAPTER 2 AMPLITUDE MODULATION: TRANSMISSION 2-1 INTRODUCTION This is a critical point in your students' study. While modulation has been introduced in Chapter 1, it is now time for the student to really come to an understanding of what it is all about. It may be a good idea to give a quiz after covering Sections 1 through 4 just to make sure that a reasonable level of comprehension has been attained. 2-2 AMPLITUDE MODULATION FUNDAMENTALS A good way to introduce the basic AM process is to compare the linear combination of two signals in Fig. 2-1 with the nonlinear combination in Fig Emphasize that only the nonlinear combination produces an AM signal. You also might want to explain why the transmission of the linear combination would leave just the carrier at the receiver while the AM signal should be received basically as transmitted. The equation defining the AM waveform is provided in equation 2-1. This is also a good opportunity to review or introduce the importance trigonometric relationship (sin x)(sin y), equation 2-2. You will find that a thorough discussion of the transmission of a range of modulation frequencies will now be possible. A detailed study of Example 2-1 should be most helpful here. The phasor analysis is also important, as for many students this is when something finally falls together, the light bulb goes on, and now they have seen the light. 2-3 PERCENTAGE MODULATION The concept of percentage modulation is usually mastered with ease. In fact, your students will probably enjoy making some quantitative calculations such as illustrated in Example 2-2. This is also a good time to introduce the concept of overmodulation and talk about the problems that it causes. 2-4 AM ANALYSIS Your students may be somewhat resistant to the brief mathematical analysis at the beginning of this section but it is important to their overall understanding. This is their first exposure to a form of modulation and they need to realize that this is not some form of magic it does withstand analysis with some basic mathematical tools. The importance of transmitting a high-percentage of modulation is now understandable just make sure they remember that overmodulation is taboo. It is now time to indicate that the carrier in AM systems effectively wastes a lot of transmitter power. Examples 2-3 through 2-8 illustrate a number of useful calculations regarding percentage modulation, total power, carrier power and sideband power. 4

12 2-5 CIRCUITS FOR AM GENERATION It is now time to introduce some circuits used to create AM. The whole key here is that it takes a nonlinear combination of carrier and intelligence to generate AM. The difference between high-level and low-level modulation is discussed. Be sure to stress that this has nothing to do with high-percentage modulation. Use Fig to help explain the difference between high and low-level modulation. It is certainly true that IC modulators are used in the majority of new designs. Introduction of several discrete device designs is still important to overall understanding and in working with older equipment. However, there is certainly nothing wrong with emphasizing the linear integrated circuit designs at this time. 2-6 AM TRANSMITTER SYSTEMS At this point it is appropriate to talk about a complete transmitter system as opposed to just the AM modulator. The citizens band transmitter described here is simple enough so that the student can comprehend the various system aspects without getting bogged down with too many details. The concept of coupling transmitter power to an antenna is introduced as is some detail on the fabrication and tuning of this compact transmitter. 2-7 TRANSMITTER MEASUREMENTS At this point your students may be anxious to learn some laboratory measurements useful in AM analysis. The trapezoid pattern technique is very good for measuring percentage modulation and for pinpointing some specific problems with the modulator. It is also important to realize that some meaningful measurements can be made with a dc ammeter. The spectrum analyzer is also introduced at this point. It is one of the most important instruments available for communication s equipment and it may be new to some of your students. Its use in making harmonic distortion measurements is provided and Example 2-9 provides a sample computation. This section is concluded with some precautions to take when making measurements on RF circuits. It is often troublesome for the beginner to understand that the measurement tool can be changing the measurement. It is important to also understand why this is happening. 2-8 TROUBLESHOOTING The first discussion has to do with the importance of initially inspecting a piece of equipment when repair is necessary. The novice is surprised at how much time is saved by this process. If inspection by itself has not cleared up the problem then a strategy for repair should be developed. This includes verification that a problem exists, isolation of the defective stage, isolation of the defective component, and replacement of the defective component. Troubleshooting a simple self-biased RF amplifier is then provided. This includes looking at the effects of various components being opened or shorted. It is very important for the student to start thinking about shorts and opens as this is such a prevalent type of failure. The process of checking an entire transmitter is the next topic. Be sure to emphasize the material on safety provided when working on high voltage systems. Troubleshooting topics covered include improper frequency of operation, measurement of output power, and how to remedy these parameters when they are not in specification. 5

13 2.9 TROUBLESHOOTING WITH ELECTRONICS WORKBENCH MULTISIM The EWB Multisim tools are used to simulate an AM modulator circuit. The student will gain additional experience measuring the modulation index of an AM signal. This exercise also enhances the students understanding of the carrier and modulating signal components of the AM envelope. The oscilloscope virtual instrument is used extensively in this exercise for making measurements on the waveform. The EWB exercises provide the opportunity for the student to test their ability to determine the modulation index and the carrier frequency of an AM signal. 6

ITT Technical Institute. ET2530 Electronic Communications Onsite and Online Course SYLLABUS

ITT Technical Institute. ET2530 Electronic Communications Onsite and Online Course SYLLABUS ITT Technical Institute ET2530 Electronic Communications Onsite and Online Course SYLLABUS Credit hours: 4.5 Contact/Instructional hours: 56 (34 Theory Hours, 22 Lab Hours Prerequisite(s and/or Corequisite(s: