Modern electronic communication

【实例简介】
感觉是比较常见的一本现代电子信息的教程，在这里分享给大家，以上。
CONTENTS Part I: Chapter Overviews Chapter I Introductory Topics Chapter 2 Amplitude modulation Transmission 4 Chapter 3 Amplitude Modulation: Reception 7 Chapter 4 Single-Sideband Communication Chapter 5 Frequency Modulation: Transmission Chapter 6: Frequency Modulation: Reception 14 Chapter 7: Communications Techniques 16 Chapter 8: Digital Communication: Coding Techniques 18 Chapter 9: Wired Digital Communication 20 Chapter 10: Wireless Digital Communications 22 Chapter 11: Network Communications 24 Chapter 12: Transmission Lines 26 Chapter 13 Wave propagation 28 Chapter 14: Antennas 30 Chapter 15: Waveguides and radar 32 Chapter 16: Microwaves and Lasers 34 Chapter 17: Television 36 Chapter 18: Fiber Optics 38 Part Il: Test Item File Chapter 1 Chapter 2 49 Chapter 3 Chapter 4 Chapter 5 87 Chapter 6 102 Chapter 7 108 Chapter 8 l12 Chapter 9 17 Chapter 10 Chapter I1 !28 Chapter 12 135 Chapter 13 143 Chapter 14 148 Chapter 15 153 Chapter 16 158 Chapter 17 162 Chapter 18 169 Part II: Answers to Chapter problems Chapte 178 189 Chapter 3 198 C hapter 206 Chapter 5 Chapter 6 OIO Chapter 7 223 Chapter 8 229 Chapter 9 234 Chapter 10 238 Chapter 11 242 Chapter 12 247 Chapter 13 271 Chapter 14 276 Chapter 15 284 Chapter 16 291 Chapter 17 296 Chapter 18 303 Part IV: Laboratory Manual Experiment Results 1 Active Filter Networks 308 Frequency Spectra of Popular Waveforms 316 345 funed Amplifiers and Frequency Multiplication 32l oow-Pass Impedance transformation Networks Phase-Shift oscillator 320 LC Feedback oscillator 333 Colpitts rF Oscillator Design 336 Hartley rF Oscillator Design 340 Swept-Frequency Measurements 343 Nonlinear Mixing Principles 349 AM Modulation Using an Operational Transconductance Amplifier 353 12 RF Mixers and Superheterodyne receivers 36l 13 Cascode∧ amplifiers 14 Sideband Modulation and Detection 378 15 Frequency Modulation: Spectral Analysis 387 16 Phase-Locked Loops: Static and Dynamic Behavior 393 17 FM Detection and Frequency Synthesis Using PLLs 399 8 Pulse Amplitude Modulation and Time Division Multiplexin 403 Pulse width modulation and detection 410 21 Digital Communication Link Using Delta Modulation Codecs 414 22 Electronics Workbench Multisim- db measurements in communications 420 23 Electronics Workbench Multisim-Smith Chart Measurements 423 USing the ewB Network Analyzer 24 Tone decoder 426 Part v Electronics Workbench multisim EWB Complementary Exercises xperiment I--EWB E 428 Simulation of an ACTIVE FILTER NETWORKS Experiment 2-EWB 430 USING THE SPECTRUM ANALYZER and the SImulation and ANALYSIS of COMPLEX WAVEFORMS Experiment3-EWB 433 Simulation of class C amplifiers and Frequency Multiplier Experiment 5-EWB 435 Simulation of a phase- Shift oscillator Experiment 6-EWB 437 Simulation of an LC Feedback oscillator Experiment 11-EWB Percentage of modulation measurement of an Amplitude modulated Waveform Notes to the instructor 440 OVERVIEW一 CHAPTER INTRODUCTORY TOPICS 1-1 INTRODUCTION Following a brief introduction to the ficld of clectronic communications, the concept of modulation is introduced. At this early stage very basic words such as a carrier"carrying" th 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-I 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 arc 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 1-3 1-3 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 1-5 1-4 NOISE DESIGNATION AND CALCULATION The important concept of signal-to-noise ratio is introduced as a simple ratio (Eg. 1-12) and in decibel form(eg. 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 ternperature, and equivalent nluise 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 intruduced A simple yet effective measurement technique using the diode noise generator is illustrated in Example 1-10. A quick and useful measurement technique using a basic dual-trace oscilloscope is detailed in Fig. 1-7. It is termed the tangential noisc measurement tcchniquc 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-matherntatical approach promotes understanding of a gI 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 I 1 and 1-12. These are the FFT representations for a sinc wavc 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- LC CIRCUITS Sections 1-7 and 1-8 cover some basic charactcristics 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. 1-21. 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. 1-29 1-9 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. 1-32 is discusscd. 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 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 propertics of a square wave, The performance and operation of these virtual instruments closely resemble real test cquipment 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 7(ms7)and Multisim 6( msm)formats. The files are located in ms 7 or msm folders in each respective chapter OVERVIEV一 CHAPTER2 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 I through 4 just to make surc that a reasonable level of comprehension has been attained 2-2 AMPLITUDE MODULATION FUNDAMENTALS A good way to introduce the basic m process is to compare the linear combination of two signals in Fig. 2-1 with the nonlincar combination in Fig. 2-2. Emphasize that only the non- linear 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 problerns that it causes 2-4 AM ANALYSIS Your students may be some what 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 inportance of tranisinilting 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 llustrate a number of useful calculations regarding percentage modulation, total power, carrier power and sideband power 4 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 Lakes a nonlinear cornbination 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. 2-12 to help explain the difference bet ween high and low-level modulation It is certainly true that IC modulators arc uscd in the majority of new designs itroduction 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 inportant 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 【实例截图】
【核心代码】