Communications Fundamentals FAQ

Chapter 2 FAQ

1. 2.7.1 What Is the Difference Between Analog and Digital Signals
   1. What Is an Analog Signal?
   2. What Is a Digital Signal?
   3. Why Are Most Modern Communications Systems Digital?
   4. What Are the Advantages of Digital Signals?
   5. Are There Any Advantages to Analog Signals?
   6. Are Communications Systems Ever Completely Digital?
   7. How Are Analog Signals Converted into Digital Signals?
   8. Will Analog Communications Disappear Completely?
2. 2.7.2 What Is a Sinusoidal Wave and Why Is It Important
   1. What Is a Sine Wave?
   2. Why Is the Sine Wave So Important?
   3. What Are Amplitude, Frequency, and Phase?
   4. What Is the Difference Between Frequency and Angular Frequency?
   5. What Is the Relationship Between Frequency and Wavelength?
   6. Why Can Complex Signals Be Represented by Sine Waves?
   7. What Are Harmonics?
   8. Why Do Engineers Often Analyze Signals in Terms of Frequency?
   9. Where Are Sinusoids Used in Communications Systems?
3. 2.7.3 What Is the Frequency Domain and Why Do Engineers Use It
   1. What Is the Difference Between the Time Domain and the Frequency Domain?
   2. Why Do Engineers Use the Frequency Domain?
   3. What Does a Signal Look Like in the Frequency Domain?
   4. What Is Fourier Analysis?
   5. How Can Complex Signals Be Broken into Simple Sine Waves?
   6. What Are Harmonics?
   7. Why Is the Frequency Domain Useful for Understanding Bandwidth?
   8. How Does the Frequency Domain Explain Filtering?
   9. Why Is the Frequency Domain Important in Radio Communications?
   10. How Is the Frequency Domain Used in Digital Communications?
   11. What Is a Spectrum Analyzer?
   12. Which Is More Important: The Time Domain or the Frequency Domain?
4. 2.7.4 What Is Bandwidth and Why Is It Important
   1. What Does Bandwidth Mean?
   2. Why Is Bandwidth Important?
   3. How Is Bandwidth Measured?
   4. Why Do Different Signals Require Different Bandwidths?
   5. Why Does a Sine Wave Occupy So Little Bandwidth?
   6. Why Does a Square Wave Require Infinite Bandwidth?
   7. What Happens When Bandwidth Is Limited?
   8. What Is Inter-Symbol Interference (ISI)?
   9. How Does Bandwidth Affect Data Rate?
   10. Is More Bandwidth Always Better?
   11. What Is Spectral Efficiency?
   12. How Do Filters Affect Bandwidth?
   13. Why Is Bandwidth Valuable?
   14. How Does Bandwidth Influence Modern Communications?
   15. Is Bandwidth the Same as Internet Speed?
5. 2.7.5 What Frequencies Are Used for Communications
   1. What Is the Electromagnetic Spectrum?
   2. What Are Audio Frequencies and Radio Frequencies?
   3. What Are the Main Radio Frequency Bands?
   4. What Are VHF, UHF, and Microwave Frequencies?
   5. Why Do Different Services Use Different Frequencies?
   6. Why Do Mobile Phones Use UHF and Microwave Frequencies?
   7. Why Do Satellite Systems Use Microwave Frequencies?
   8. What Frequencies Are Used by Fiber-Optic Systems?
   9. What Is Free-Space Optical Communication?
   10. What Are Terahertz Communications?
   11. How Does Frequency Affect Antenna Size?
   12. Will Communications Systems Continue to Move to Higher Frequencies?
6. 2.7.6 How Much Bandwidth Does Human Speech Require
   1. What Frequencies Are Present in Human Speech?
   2. What Is the Difference Between Voice Frequency and Audio Frequency?
   3. Why Do Telephone Systems Use 300 Hz to 3.4 kHz?
   4. Why Can Speech Be Understood with Such Limited Bandwidth?
   5. Which Frequencies Are Most Important for Speech?
   6. Why Does Music Require More Bandwidth Than Speech?
   7. What Is Wideband Speech?
   8. What Is Fullband Speech?
   9. How Is Speech Converted into Digital Form?
   10. Why Is Speech Compression Possible?
   11. How Does Speech Bandwidth Affect Communications Systems?
   12. Will Future Systems Use More Speech Bandwidth?
7. 2.7.7 What Is the Difference Between Bit Rate and Baud Rate
   1. What Is a Bit?
   2. What Is Bit Rate?
   3. What Is a Symbol?
   4. What Is Baud Rate?
   5. Why Were Bit Rate and Baud Rate Once the Same?
   6. Why Are Bit Rate and Baud Rate Not Always the Same?
   7. What Is an M-ary Signal?
   8. How Many Bits Can One Symbol Represent?
   9. What Is the Relationship Between Bit Rate and Baud Rate?
   10. Why Can't Engineers Simply Increase the Baud Rate?
   11. How Do Modulation Schemes Affect Bit Rate?
   12. Does a Higher-Order Modulation Always Improve Performance?
   13. Why Is Baud Rate Important?
   14. Why Are the Terms Still Confused?
8. 2.7.8 What Limits the Speed of a Communications System
   1. What Determines the Maximum Data Rate of a Communications System?
   2. Why Does Bandwidth Limit Data Rate?
   3. What Is the Nyquist Criterion?
   4. Why Is the Nyquist Criterion Important?
   5. What Is Inter-Symbol Interference (ISI)?
   6. How Do Raised-Cosine Filters Reduce ISI?
   7. Does the Nyquist Criterion Determine the Maximum Data Rate?
   8. What Is the Shannon-Hartley Theorem?
   9. What Does Channel Capacity Mean?
   10. How Does Noise Limit Data Rate?
   11. What Is Signal-to-Noise Ratio (SNR)?
   12. Can Data Rate Be Increased Without Increasing Bandwidth?
   13. Can Data Rate Be Increased Without Increasing Power?
   14. Why Is Spectral Efficiency Important?
   15. How Close Can Modern Systems Get to the Shannon Limit?
   16. Do Fiber-Optic Systems Also Have Limits?
   17. Why Are These Limits Important?
9. 2.7.9 What Is the Difference Between Synchronous and Asynchronous Transmission
   1. Why Is Timing Important in Digital Communications?
   2. What Is Asynchronous Transmission?
   3. Why Is It Called Asynchronous?
   4. What Are Start and Stop Bits?
   5. What Are the Advantages of Asynchronous Transmission?
   6. What Are the Disadvantages of Asynchronous Transmission?
   7. Where Is Asynchronous Transmission Used?
   8. What Is Synchronous Transmission?
   9. How Is Synchronization Maintained?
   10. What Are the Advantages of Synchronous Transmission?
   11. What Are the Disadvantages of Synchronous Transmission?
   12. Which Method Is More Efficient?
   13. How Do Modern Networks Use Synchronization?
   14. What Is Isochronous Transmission?
   15. Why Is Synchronization Important in Modern Communications?
   16. Which Method Is Better?