Contents Preface xiii Part I 1 Chapter 1 Introduction to Frequency-Modulated Continuous-Wave 3 Radar 1.1 Brief History 3 1.2 Examples of Use of FMCW Radar 5 1.2.1 Radio Altimeters 5 1.2.2 Level-Measuring Radar 6 1.2.3 Navigational Radar 6 1.2.4 Vehicle Collision Warning Systems 7 1.2.5 Precision Range Meter for Fixed Targets 8 1.2.6 Measurement of Very Small Motions 9 References 9 Chapter 2 Basic Theory of Short-Range FM Radar 11 2.1 Principle of Operation and Basic Block Diagram of FM Radar 11 2.2 Typical Block Diagram of Short-Range FM Radar 13 2.2.1 System with Separate Transmitting and Receiving Antennas and Nonzero Intermediate Frequency 13 2.2.2 Circuit with Nonzero Intermediate Frequency and Complex Frequency Modulation 14 2.2.3 System with a Single Transmitting-Receiving Antenna 15 2.2.4 Autodyne System with a Single Antenna 16 vii
viii Fundamentals of Short-Range FM Radar 2.3 General Expressions for Transmitted, Reflected, and Converted Signals 16 2.4 General Relationships for the Converted Signal with Modulation by a Periodic Function 19 2.5 General Relations for a Converted Signal with Dual- Frequency Modulation 22 2.6 General Relations for a Converted Signal with Modulation by a Modulated Periodic Function 24 2.7 Block Diagrams of Ultrasonic SRR and Features of the Converted Signal 25 Chapter 3 Characteristics of the Converted Signal with Different Transmitter Modulations 27 3.1 Sinusoidal Modulation 27 3.1.1 Modulation by a Single Sinusoid 27 3.1.2 Dual Sinusoidal Modulation 31 3.2 Linear Frequency Modulation 33 3.2.1 Modulation with an Asymmetrical Sawtooth Function 33 3.2.2 Modulation with Non-Isosceles and Symmetrical Sawtooth Functions 39 3.3 Discrete Modulation 42 3.4 Effects of Transmitter Modulation Nonlinearity on Converted Signal Parameters 45 Chapter 4 Integrated Methods of Converted Signal Processing 49 4.1 General Description 49 4.2 Effect of Parasitic Amplitude Modulation of the Transmission on Operation of the SRR Receiver 52 4.2.1 General Description 52 4.2.2 Methods of Decreasing PAM Signal Effects on Receiver Operation 54 4.3 Stabilization of the Frequency Deviation 59 4.4 Frequency Processing of the Converted Signal 63 4.4.1 Range Finding by Counting the Number of Zero Points of the Converted Signal for a Modulation Period 63 4.4.2 Measuring of the Instantaneous Frequency 65 4.4.3 Fixing the Instantaneous Frequency of the Converted Signal 67 4.4.4 Use of the Frequency Deviation of the Converted Signal 68 4.4.5 Applying Dual Sinusoidal Modulation 71
Contents ix 4.4.6 Single-Antenna Version with Zero Intermediate Frequency 75 4.4.7 Fixing the Frequency Deviation of the Converted Signal 76 4.5 Phase Processing of the Converted Signal 81 References 88 Chapter 5 Spectral Methods of Processing the Converted Signal 89 5.1 General Description 89 5.2 Range Resolution 93 5.3 Radar Scan of Range 99 5.4 Spectral Processing Using the Parasitic AM Signal 109 5.5 Signal Processing on Separate Components of the Converted Signal Spectrum 111 5.5.1 Formation of the Discriminator Characteristic 111 5.5.2 Phase Processing of Separate Components of the Converted Signal Spectrum 113 References 122 Part II 123 Chapter 6 Analysis of Constant Frequency Oscillators 125 6.1 Rule for Obtaining the Abbreviated Equations 126 6.2 Substantiation of the SAE Method 129 6.3 Examples of Deriving the Abbreviated Equations 133 6.3.1 Single-Tuned Oscillator with Fixed Bias Voltage 133 6.3.2 Single-Tuned Oscillator with Automatic Bias 137 6.4 General Abbreviated and Characteristic Equations of Anisochronous Oscillators 140 6.4.1 Abbreviated Equations of Anisochronous Oscillators 141 6.4.2 Stationary Modes of the Oscillator 144 6.4.3 General Characteristic Equation of the Anisochronous Oscillator 145 6.4.4 Condition of Self-Excitation of Oscillators with Inertial Active Elements 148 6.4.5 Order of the Characteristic Equation and the Sign of the Factor at the Upper Derivative 149 References 150 Chapter 7 Analysis of FM Systems Using Symbolical Abbreviated Equations 151 7.1 Symbolical Abbreviated Equations for Controlled Self- Oscillatory Systems of Any Kind 151
x Fundamentals of Short-Range FM Radar 7.2 Method of Symbolical Abbreviated Equations for FM Systems 156 7.3 Differential Equations of Some FM Systems 159 7.3.1 Differential Equations of a Parallel Conservative LC Circuit with Variable Capacitance and an Active Two-Pole 159 7.3.2 Differential Equations of a Parallel Dissipative LC Circuit with Variable Capacitance and an Active Two-Pole 161 7.4 Abbreviated Differential Equations of Single-Tuned Oscillators with Sinusoidal FM 162 7.5 Parasitic Amplitude Modulation in Autodynes for Various Types of Frequency Modulation 165 7.5.1 Sine Wave Frequency Modulation 169 7.5.2 Binary Frequency Modulation 170 7.5.3 Frequency Modulation by an Asymmetrical Sawtooth 170 7.5.4 Frequency Modulation with a Symmetrical Sawtooth 171 References 172 Chapter 8 Output Voltage of a Frequency-Controlled Oscillator 173 8.1 Change of Output Voltage for Oscillators Tuned Discretely in Time 174 8.2 Parasitic Amplitude Modulation of Oscillations in Ideal Single-Tuned Circuits with Modulation of Their Natural Frequencies 180 8.3 Parasitic Amplitude Modulation of Output Voltage in Single-Tuned Oscillators with Frequency Modulation 183 8.4 Use of a Varicap as the Frequency Controller 193 References 200 Chapter 9 Nonlinearity and Linearization in Varactor Control of FM Oscillators 201 9.1 Nonlinearity of Frequency Dependence of Single-Tuned Oscillators on Control Voltage of the Varactor with Large Frequency Changes 203 9.2 Nonlinear Distortions with Frequency Modulation Using Varactors 209 9.2.1 Nonlinear Distortions for Capacitor Coupling of the Varactor to the Oscillator Circuit 210
Contents xi 9.2.2 Nonlinear Distortions for Autoinductive Coupling of the Varactor to the Oscillator Circuit 212 9.2.3 Nonlinear Distortions in the Case of a Single- Tuned Oscillator Circuit with Allowance for RF Voltage on the Varactor 213 9.3 Linearization of Dependence of Oscillator Frequency on Control Voltage 215 9.4 Calculation of Diode-Resistive Correction Circuits 221 9.5 Decreasing the Nonlinear Distortion of the FM Signal with a Correcting Signal 223 Chapter 10 Theory of the Single-Tuned Transistor Autodyne and Optimization of Its Modes 227 10.1 Abbreviated Differential Equations for the Single-Tuned Transistor Autodyne 228 10.2 Linearized Differential Equations of Autodynes for Small Reflected Signals 231 10.3 Equivalent Circuits of Autodynes for Small Reflected Signals 233 10.4 The Form and Spectrum of the Output Signal of a Single-Tuned Transistor Autodyne 234 10.5 Form and Spectrum of the High-Frequency Signal from an FM Transistor Autodyne 239 10.6 Transfer Factors of an Autodyne on a Voltage and a Current and Mode Optimization 242 10.6.1 Analysis for Low Frequencies for a Particular Transistor 242 10.6.2 The High-Frequency Case 246 10.6.3 Choice of Mode with High Autodyne Sensitivity 247 References 248 Chapter 11 Autodyne Modes of Transistor Oscillators with Strong Interference 249 11.1 The Common Properties of Autodyne Modes of the Single-Tuned Synchronized Oscillator 250 11.1.1 Abbreviated Equations for the Synchronized Oscillator 250 11.1.2 Abbreviated Equations in Normalized Parameters 252 11.1.3 Steady-State Synchronous Modes 255 11.1.4 Transients at Synchronism 257 11.1.5 Bifurcational Diagrams of a Transistor 260 Autodyne
xii Fundamentals of Short-Range FM Radar 11.2 Transfer Factor of an Autodyne Subject to Synchronous Jamming 263 11.3 Bifurcations of Periodic Variations in the Synchronized Autodyne 269 References 273 List of Symbols 275 About the Authors 281 Index 285