 | Baumgartner S.V. Traffic monitoring with air- and spaceborne synthetic aperture radar: Diss. … Dr-Ing. / Deutsches Zentrum fur Luft- und Raumfahrt, Institut für Hochfrequenztechnik und Radarsysteme, Oberpfaffenhofen. - Köln: DLR, 2014. - xiv, 220 p.: ill. - (Forschungsbericht; 2014-28). - Bibliogr.: p.193-206. - ISSN 1434-8454
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Acronyms and Symbols ............................................ v
1 Introduction ................................................. 1
1.1 History and State-of-the-Art in Moving Target
Indication .............................................. 4
1.2 Motivation, Objectives and Thesis Contributions ......... 9
1.3 Structure of the Thesis ................................ 11
2 Synthetic Aperture Radar and Moving Targets ................. 13
2.1 Synthetic Aperture Radar Principle ..................... 13
2.1.1 Acquisition Geometry and Operation .............. 13
2.1.2 Stationary Point Target Signal Model ............ 16
2.1.3 Pulse Compression and Image Formation ........... 19
2.2 Moving Point Target Signal Model ....................... 22
2.2.1 Single-Channel Signal Model ..................... 22
2.2.2 Multi-Channel Signal Model ...................... 25
2.3 Effects on SAR Imagery ................................. 28
2.3.1 Residual Range Cell Migration ................... 28
2.3.2 Along-Track Velocity ............................ 31
2.3.3 Across-Track Velocity ........................... 34
2.3.4 Along-Track Acceleration ........................ 38
2.3.5 Across-Track Acceleration ....................... 39
2.3.6 Summary of Effects .............................. 40
3 Moving Target Detection and Parameter Estimation: Basic
Methods ..................................................... 43
3.1 Basic Structure of a GMTI Processor .................... 43
3.1.1 Preprocessing ................................... 44
3.1.2 Clutter Suppression ............................. 45
3.1.3 Detection ....................................... 45
3.1.4 Signal Extraction ............................... 48
3.1.5 Parameter Estimation ............................ 49
3.1.6 Visualization ................................... 54
3.2 Classical Dual-Channel Ground Moving Target
Indication ............................................. 55
3.2.1 Along-Track Interferometry ...................... 55
3.2.2 Displaced Phase Center Antenna Technique ........ 61
3.3 Detection and Parameter Estimation Methods ............. 64
3.3.1 Matched Filter Bank ............................. 64
3.3.2 Fractional Fourier Transform .................... 67
3.3.3 Time-Frequency Analysis ......................... 70
3.3.4 Radon Transform ................................. 71
3.3.5 Space-Time Adaptive Processing .................. 72
4 Acceleration-Independent Target Velocity Estimation ......... 79
4.1 Introduction ........................................... 79
4.2 Mathematical Relationship .............................. 80
4.2.1 Dual-Channel Case ............................... 80
4.2.2 Multi-Channel Case - Uniformly Distributed RX
Antennas ........................................ 83
4.2.3 Non-Uniformly Distributed RX Antennas ........... 85
4.3 Algorithm .............................................. 86
4.3.1 Moving Target Signal Extraction ................. 86
4.3.2 Parameter Estimation ............................ 89
4.4 Estimation Accuracy .................................... 90
4.4.1 Comparison to Matched Filter Bank ............... 94
4.5 Experimental Results ................................... 97
4.5.1 Dual-Channel Results ............................ 97
4.5.2 Four-Channel Results ............................ 99
4.6 Conclusion and Outlook ................................ 101
5 A Priori Knowledge-Based Airborne Traffic Monitoring With
Real-Time Capability ....................................... 103
5.1 Introduction .......................................... 103
5.2 Algorithm ............................................. 104
5.2.1 Principle ...................................... 104
5.2.2 Structure of the Algorithm ..................... 105
5.2.3 Coordinate Transformation ...................... 108
5.2.4 Motion Parameter Estimation .................... 113
5.3 Parameter Estimation Performance Assessment ........... 116
5.3.1 Coordinate Transformation Errors ............... 117
5.3.2 Utilizable Azimuth Samples ..................... 119
5.3.3 Velocity Resolution Without Deramping .......... 120
5.3.4 Velocity Resolution Using Deramping ............ 124
5.3.5 Velocity Resolution Using Adaptive Deramping ... 126
5.3.6 Roads Parallel to Flight Direction ............. 127
5.3.7 Detectable Velocity Range ...................... 128
5.3.8 Multi-Component Signals ........................ 129
5.3.9 Occurrence of Ambiguities and False
Detections ..................................... 131
5.3.10 Recognition and Cancellation of Ambiguities
and False Detections ........................... 133
5.4 Detection Performance Assessment ...................... 134
5.4.1 SNR and CNR Computation ........................ 135
5.4.2 STAP Detection Performance ..................... 136
5.5 Experimental Results .................................. 139
5.5.1 Over-Sampled Data in Azimuth ................... 140
5.5.2 Under-Sampled Data in Azimuth .................. 143
5.6 Conclusion and Outlook ................................ 145
6 Dual-Platform Large Along-Track Baseline GMTI .............. 149
6.1 Introduction .......................................... 149
6.2 Moving Target Signal Model ............................ 151
6.3 Moving Target Displacements ........................... 154
6.4 GMTI Algorithm ........................................ 157
6.4.1 SAR Preprocessing and Calibration .............. 159
6.4.2 Clutter Suppression and Detection .............. 159
6.4.3 2D Cross-Correlation ........................... 160
6.4.4 Simple Parameter Estimation Method ............. 164
6.4.5 Advanced Parameter Estimation Method ........... 165
6.5 Performance Assessment ................................ 166
6.5.1 Line-of-Sight Acceleration Estimation
Accuracy ....................................... 167
6.5.2 Repositioning Accuracy ......................... 170
6.5.3 Velocity and Moving Direction Estimation
Accuracy ....................................... 171
6.6 Experimental Results .................................. 174
6.6.1 Maritime Traffic ............................... 174
6.6.2 Land Traffic ................................... 180
6.7 Conclusion ............................................ 186
7 Discussion and Outlook ..................................... 189
7.1 Discussion ............................................ 189
7.2 Future Work and Outlook ............................... 190
Bibliography .................................................. 193
A Range and Doppler History Approximation .................... 207
A.l Taylor Series Expansion of the Range History ........... 207
A.2 Quadratic Approximation of the Doppler History ......... 208
8 Moving Target Signal After Channel Co-Registration ......... 211
С General DPCA-ATI Phase Computation ....................... 213
D Dual-Platform GMTI Parameter Estimation Accuracies ......... 215
D.l Along-Track Repositioning Accuracy ..................... 215
D.2 Range Repositioning Accuracy ........................... 216
D.3 Along-Track Velocity Estimation Accuracy ............... 216
D.4 Across-Track Velocity Estimation Accuracy .............. 216
D.5 Absolute Velocity Estimation Accuracy .................. 217
D.6 Moving Direction Estimation Accuracy ................... 217
D.7 Line-of-Sight Acceleration Estimation Accuracy ......... 218
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