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Contents 0.1 Introduction .................................... 1 1 Communications Basics 3 1.1 Wideband vs Narrowband ............................ 3 1.2 Frequency Spectrum ............................... 3 1.3 Time Division Multiplexing ........................... 3 1.4 Zero Substitutions ................................ 10 1.5 Benefits of TDM ................................. 15 1.6 Synchronous TDM ................................ 15 1.7 Statistical TDM ................................. 16 1.8 Packets ...................................... 19 1.9 Duty Cycles .................................... 19 1.10 Introduction .................................... 19 1.11 What is FDM? .................................. 21 1.12 Benefits of FDM ................................. 23 1.13 Examples of FDM ................................ 23 1.14 Orthogonal FDM ................................. 23 1.15 Voltage Controlled Oscillators (VCO) ..................... 23 1.16 Phase-Locked Loops ............................... 24 1.17 Purpose of VCO and PLL ............................ 24 1.18 Varactors ..................................... 24 1.19 Further reading .................................. 24 1.20 What is an Envelope Filter? ........................... 24 1.21 Circuit Diagram ................................. 25 1.22 Positive Voltages ................................. 25 1.23 Purpose of Envelope Filters ........................... 25 1.24 Definition ..................................... 26 1.25 Types of Modulation ............................... 26 1.26 Why Use Modulation? .............................. 27 1.27 Examples ..................................... 27 1.28 non-sinusoidal modulation ............................ 27 1.29 further reading .................................. 28 1.30 What are They? ................................. 28 1.31 What are the Pros and Cons? .......................... 28 1.32 Sampling and Reconstruction .......................... 29 1.33 further reading .................................. 29 1.34 Twisted Pair Wire ................................ 30 1.35 Coaxial Cable ................................... 30 1.36 Fiber Optics .................................... 31 1.37 Wireless Transmission .............................. 31 1.38 Receiver Design .................................. 32 III Contents 1.39 The Simple Receiver ............................... 32 1.40 The Optimal Receiver .............................. 32 1.41 Conclusion ..................................... 33 1.42 further reading .................................. 33 2 Analog Modulation 35 2.1 Analog Modulation Overview .......................... 35 2.2 Types of Analog Modulation .......................... 35 2.3 The Breakdown .................................. 35 2.4 How we Will Cover the Material ........................ 35 2.5 Amplitude Modulation .............................. 36 2.6 AM Demodulation ................................ 56 2.7 AM-DSBSC .................................... 60 2.8 AM-DSB-C .................................... 62 2.9 AM-SSB ...................................... 63 2.10 AM-VSB ..................................... 70 2.11 Frequency Modulation .............................. 71 2.12 FM Transmission Power ............................. 77 2.13 FM Transmitters ................................. 78 2.14 FM Receivers ................................... 78 2.15 Phase Modulation ................................ 78 2.16 Wrapped/Unwrapped Phase ........................... 88 2.17 PM Transmitter ................................. 88 2.18 PM Receiver ................................... 88 2.19 Concept ...................................... 89 2.20 Instantaneous Phase ............................... 89 2.21 Instantaneous Frequency ............................. 89 2.22 Determining FM or PM ............................. 90 2.23 Bandwidth .................................... 90 2.24 The Bessel Function ............................... 91 2.25 Carson's Rule ................................... 91 2.26 Demodulation: First Step ............................ 91 2.27 Filtered Noise ................................... 92 2.28 Noise Analysis .................................. 92 3 Transmission 95 3.1 Electromagnetic Spectrum ............................ 95 3.2 Radio Waves ................................... 95 3.3 Fading and Interference ............................. 101 3.4 Reflection ..................................... 105 3.5 Diffraction ..................................... 106 3.6 Path Loss ..................................... 106 3.7 Rayleigh Fading .................................. 106 3.8 Rician Fading ................................... 106 3.9 Doppler Shift ................................... 106 3.10 Types of Noise .................................. 106 3.11 Noise Temperature ................................ 111 3.12 Noise Figure .................................... 111 IV Contents 3.13 Receiver Sensitivity ................................ 114 3.14 Cascaded Systems ................................ 114 3.15 Transmission Line Equation . 115 3.16 The Frequency Domain ............................. 122 3.17 Characteristic Impedance ............................ 126 3.18 Isotropic Antennas ................................ 126 3.19 Directional Antennas ............................... 128 3.20 Link-Budget Analysis .............................. 129 3.21 Further reading .................................. 130 3.22 Technical categorisations ............................. 130 3.23 Multipathing ................................... 130 3.24 Application systems ............................... 130 4 Digital Modulation 131 4.1 Definition ..................................... 131 4.2 Square Wave ................................... 131 4.3 Other pulses .................................... 132 4.4 Sinc ........................................ 132 4.5 Comparison .................................... 132 4.6 slew-rate-limited pulses ............................. 132 4.7 Raised-Cosine Rolloff ............................... 132 4.8 Binary symmetric pulses ............................. 133 4.9 Asymmetric Pulses ................................ 133 4.10 Asymmetric Correlation Receiver . 133 4.11 References ..................................... 133 4.12 What is "Keying?" ................................ 134 4.13 Amplitude Shift Keying ............................. 134 4.14 Frequency Shift Keying ............................. 135 4.15 Phase Shift Keying ................................ 136 4.16 Binary Transmitters ............................... 137 4.17 Binary Receivers ................................. 137 4.18 Pronunciation ................................... 137 4.19 Example: 4-ASK ................................. 137 4.20 Bits Per Symbol ................................. 137 4.21 QPSK ....................................... 138 4.22 CPFSK (MSK) .................................. 138 4.23 DPSK ....................................... 138 4.24 For further reading ................................ 138 4.25 Definition ..................................... 138 4.26 Constellation Plots ................................ 139 4.27 Benefits of QAM ................................. 139 4.28 For further reading ................................ 139 4.29 Definition ..................................... 140 4.30 Constellation Plots ................................ 140 4.31 Benefits of QAM ................................. 141 4.32 For further reading ................................ 141 4.33 Line Codes .................................... 141 4.34 Non-Return to Zero Codes (NRZ) . 144 V Introduction 4.35 Manchester .................................... 146 4.36 Differential Codes ................................. 146 4.37 Comparison .................................... 147 4.38 further reading .................................