1 Introduction ................................................. 1
1.1 Radar remote sensing .................................... 1
1.2 SAR tomography .......................................... 3
1.3 Thesis contribution ..................................... 4
2 Synthetic Aperture Radar Imaging ............................. 7
2.1 SAR resolution .......................................... 7
2.2 SAR processing .......................................... 9
2.2.1 Range compression ............................... 10
2.2.2 Azimuth compression ............................. 10
2.3 2-D SAR focusing algorithms ............................ 13
2.3.1 Range cell migration ............................ 14
2.3.2 Motion deviations ............................... 15
2.4 Topography dependent motion compensation ............... 19
3 SAR Interferometry .......................................... 21
3.1 Height retrieval ....................................... 22
3.2 Correlation and coregistration ......................... 27
3.2.1 Residual motion errors .......................... 30
3.3 Polarimetric SAR interferometry ........................ 30
4 SAR Tomography .............................................. 33
4.1 Introduction ........................................... 33
4.2 SAR Tomography ......................................... 34
4.2.1 Basic equations ................................. 36
4.2.2 Polarimetric SAR Tomography ..................... 39
4.2.3 Phase calibration ............................... 41
4.3 Direction of arrival (DOA) estimation methods .......... 42
4.3.1 Capon method .................................... 45
4.3.2 Parametric methods: MUSIC ....................... 48
4.4 DO A algorithm for SARTom .............................. 50
5 Experimental data sets ...................................... 53
5.1 Oberpfaffenhofen data set - PolTom campaign ............ 54
5.2 Dornstetten dataset - SARTom campaign .................. 55
5.2.1 Target specifications ........................... 59
6 Advanced tomographic SAR processing ......................... 61
6.1 Time domain beamforming approach ....................... 61
6.2 Height dependent motion compensation and
coregistration ......................................... 65
6.2.1 Motivation ...................................... 65
6.2.2 Height dependent Motion Compensation ............ 67
6.2.3 Experimental Results ............................ 69
6.3 Required Accuracy ...................................... 73
6.4 Phase calibration without the need of a CR ............. 76
7 Imaging and feature extraction of targets hidden beneath
vegetation .................................................. 79
7.1 Corner reflectors tomographic results analysis ......... 79
7.2 First tomographic images of targets hidden beneath
foliage ................................................ 83
7.3 Polarimetric analysis .................................. 85
7.3.1 Results obtained by means of the TDB ............ 85
7.3.2 Target features extraction ...................... 90
7.3.3 Truck height estimation ......................... 95
8 Minimum number of tracks for SAR tomography ................. 97
8.1 Problem Formulation .................................... 98
8.2 Distributed Source Model .............................. 100
8.3 Minimum Number of Tracks .............................. 101
8.3.1 Number of dominant eigenvalues estimation ...... 102
8.3.2 Non continuous acquisition case: SARTom ........ 103
8.4 Minimum tomographic aperture length ................... 105
8.5 Numerical examples .................................... 107
8.5.1 Airborne case: L-band .......................... 107
8.5.2 Airborne case: P-band .......................... 111
8.5.3 Spaceborne case: C-band ........................ 111
8.6 Experimental results .................................. 112
9 Conclusions and outlook .................................... 119
A Appendix ................................................... 127
A.l Sampling regularization ............................... 127
A.2 Ground and canopy contributions ....................... 128
A.3 Space-bandwidth parameter derivations ................. 129
A.4 Overlap case for the distributed scatterer model ...... 130
A.5 Ambiguity control for spaceborne mission over ice ..... 132
A.5.1 Volume of ambiguity reduction ю................. 133
A.6 Tomographic constellation design by means of minimum
redundancy array theory (MRA) ......................... 137
Bibliography .................................................. 138
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