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Microwaves and Radar Institute [email protected]
Distributed Imaging with TSX and TDXDistributed Imaging with TSX and TDX
Pau Prats, Paco López-Dekker, Francesco De Zan, Steffen Wollstadt, Markus Bachmann, Ulrich Steinbrecher, Rolf Scheiber, Andreas Reigber, Gerhard Krieger
Microwaves and Radar Institute (HR)German Aerospace Center
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 2Microwaves and Radar Institute
Motivation
Future SAR missions will exploit bi- and multistatic SAR systems.
Such systems increase the potential, reliability and flexibility of future SAR missions.
Potential: frequent monitoring, wide-swath imaging, single-pass interferometry, enhanced products (e.g. in terms of resolution).
Perform new experiments! ;c)
G. Krieger and A. Moreira, “Spaceborne bi- and multistatic SAR: potential and challenges”, IEE Proc.-Radar Sonar Navig., vol. 153, no. 3, June 2006.
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 3Microwaves and Radar Institute
VU 3 > Alberto Moreira
• SAR Interferometer• Close formation• Global DEM (HRTI-3)
TerraSAR-X add on for Digital Elevation Measurements
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 4Microwaves and Radar Institute
VU 4 > Alberto Moreira
Bistatic SAR ImagingBistatic SAR ImagingBistatic SAR ImagingBistatic SAR Imaging
Super ResolutionSuper ResolutionSuper ResolutionSuper Resolution
Polarimetric SAR InterferometryPolarimetric SAR InterferometryPolarimetric SAR InterferometryPolarimetric SAR Interferometry
Ground Moving Target IndicationGround Moving Target IndicationGround Moving Target IndicationGround Moving Target Indication
SAR TomographySAR TomographySAR TomographySAR Tomography
SeaSea ice monitoring ice monitoringSeaSea ice monitoring ice monitoring
RxTx
Double Differential InterferometryDouble Differential InterferometryDouble Differential InterferometryDouble Differential Interferometry
h(t1)
h ~ 2 - 1
coherence between passes not mandatory
1
pass 1
pass 2
h < 10 cmh(t2)
2
Bistatic Strip mapB = 3000 m x = 12 m
Bistatic Strip mapB = 3000 m x = 12 m
Digital BeamformingDigital BeamformingDigital BeamformingDigital Beamforming
without reconstruction with reconstruction
Ch. 2Ch. 1
SAR Proc.
P2(f)P2(f) P3(f)P3(f)P1(f)P1(f) P4(f)P4(f)
EnablesHigh
ResolutionWide Swath
Imaging
Ch. 3 Ch. 4
AmbiguitySuppression
Rx1 Rx2
B1
B2
B3
TanDEM-X: Secondary Mission Objectives
Crossed-orbitsCrossed-orbitsCrossed-orbitsCrossed-orbits
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 5Microwaves and Radar Institute
Some Experiments with Distributed Imaging
Demonstration of distributed imaging with the following experiments:
Range-resolution enhancement
Azimuth-resolution enhancement
Quad-pol synthesis with dual-pol acquisitions
Digital beamforming
Elaborated manual commanding of each experiment
Experiments performed during the monostatic commissioning phase:
20 km ~ 3 s
TSXTDX
Baseline needs to be
compensated
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 6Microwaves and Radar Institute
TanDEM-X Commissioning Phase
June‘10 July‘10 Aug‘10 Sep‘10 Oct‘10 Nov‘10 Dec‘10
EarlyOrbitPhase
Grg SegmentCheckout
Bi-static Commissioning Phase
20 km FormationTDX Orbit Drift16.000 km 20 km Close Helix-Formation 300-400 mLaunch
21 June
DEM Acquisition
First SAR Image 24 June (MET +3.6)
First DEM 16 July (MET +25)
TDX Monostatic Comm. Phase
6 Months Commissioning Phase
First close formation DEM 19 October (MET +124)
First bi-static SAR image 8 August (MET +48)
First single-pass bi-static DEM 2 October (MET +107)
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 7Microwaves and Radar Institute
Super Resolution in Range: Step-Frequency with TSX and TDX
f0 - f
f0 + f
f0
fr
fr
fr
TSX
TDX
Limitation: RF filter allows maximum band of 300 MHz
Advantages within limitation:
Increased SNR
Data rate distributed among satellites
Baseline compensation for proper coherent combination
Negligible spectral shift for current configurations (but nevertheless considered)
300 MHz
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 8Microwaves and Radar Institute
Super Resolution in Range: Step-Frequency with TSX and TDX
4ˆ , ,cal r x r r x
,r r xInterferometric chain
(TAXI)Common range-band
filter
ECS + BAS (TAXI)Shift after range compression due to
non-centered chirp spectrum
TSXraw data
TDXraw data
TSX SLC TDX SLC
Calibration phase
Phase and gain calibrationCoherent addition
Weighting
Range-resolution- enhanced SLC
Coregistered TDX SLC
(non-filtered)
Coregistration
Common-band spectruminterferogram
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 9Microwaves and Radar Institute
Super Resolution in Range: Experimental Setup
Data takes over Sydney, Australia, on August 15 and 26, 2010
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 10Microwaves and Radar Institute
Super Resolution in Range: Experimental Results
azim
uth
range
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 11Microwaves and Radar Institute
Super Resolution in Range: Experimental Results (II)
azim
uth
range
Common-band interferogram
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 12Microwaves and Radar Institute
Super Resolution in Range: Experimental Results (III)
azim
uth
range
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 13Microwaves and Radar Institute
Super Resolution in Range: Experimental Results (IV)
azim
uth
range
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 14Microwaves and Radar Institute
Super Resolution in Range: Experimental Results (V)
azim
uth
range
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 15Microwaves and Radar Institute
Super Resolution in Range: Experimental Results (VI)
azim
uth
range
Interferometric coherence between synthesized images
Interferometric phase between synthesized images
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 16Microwaves and Radar Institute
Super Resolution in Azimuth
fDC,1
fDC,2
fDC,mean
fa
fa
fa
TSX
TDXInterferometric chain
(TAXI)Common azimuth-band
filter
ECS (TAXI)
TSXraw data
TDXraw data
TSX SLC TDX SLC
Calibration phase
Phase and gain calibrationCoherent addition
Weighting
Azimuth-resolution- enhanced SLC
Coregistered TDX SLC
(non-filtered)
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 17Microwaves and Radar Institute
Super Resolution in Azimuth: Experimental Setup
Data take over Neustrelitz, Germany, on September 20, 2010
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 18Microwaves and Radar Institute
Super Resolution in Azimuth: DTAR AnalysisTDXDTAR: -21.67 dB
TSXDTAR: -21.04 dB
Maximum bandwidthDTAR: -19.91 dB
Twice the resolutionDTAR: -21.42 dB
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 19Microwaves and Radar Institute
Super Resolution in Azimuth: Experimental Results (I)
azimuth
range
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 20Microwaves and Radar Institute
Super Resolution in Azimuth: Experimental Results (II)
azimuth
range
Common-band interferogram
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 21Microwaves and Radar Institute
Super Resolution in Azimuth: Experimental Results (III)
azim
uth
range
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 22Microwaves and Radar Institute
Super Resolution in Azimuth: Experimental Results (IV)
azim
uth
range
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 23Microwaves and Radar Institute
Super Resolution in Azimuth: Experimental Results (V)
azim
uth
range
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 24Microwaves and Radar Institute
Super Resolution in Azimuth: Experimental Results (VI)
Measured resolutions over a corner reflector:
TSX: 2.97m
TDX: 2.97 m
Combined: 1.49 m
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 25Microwaves and Radar Institute
Quad-Pol Synthesis with Dual-Pol Acquisitions
Each satellite acquires a co-pol and a cross-pol channel, e.g. HH-VH and HV-VV
The cross-pol channel is used to estimate the calibration phase
Better SNR and DTAR when compared to the experimental quad-pol product using the dual receive antenna (DRA) mode
DLR’s E-SAR example: quad-pol synthesis at C-band with repeat-pass dual-pol acquisitions [1]
E-SAR
[1] R. Scheiber et al., “Radar data processing, quality analysis and level-1b product generation for AGRISAR and EAGLE campaigns,” in AGRISAR and EAGLE Campaigns Final Workshop, Noordwijk, The Netherlands, Oct. 15-16 2007.
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 26Microwaves and Radar Institute
Quad-Pol Synthesis: Experimental Results
New acquisitions performed in bistatic mode are on their way.
azimuth
range
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 27Microwaves and Radar Institute
Conclusion & Future Work
Proof of concept of several experiments with TSX and TDX
Range-resolution enhancement
Azimuth-resolution enhancement
Quad-pol synthesis with dual-pol acquisitions
Qual-pol synthesis with dual-pol acquisitions using bistatic data (close formation)
Further performance analyses, especially for the azimuth case
By doubling the PRF one can obtain simultaneously a resolution improvement in both dimensions
Digital beamforming with an interferometric baseline
Microwaves and Radar Institute > Februar 2010 July 29th, 2011Slide 28Microwaves and Radar Institute
VU 28 > Alberto Moreira
Thank you for your attention!