first bistatic spaceborne sar experiments with tandem-x.ppt

Microwaves and Radar Institute [email protected]

First Bistatic Spaceborne SAR Experiments First Bistatic Spaceborne SAR Experiments with TanDEM-Xwith TanDEM-X

Marc Rodriguez-Cassola, Pau Prats, Daniel Schulze, Núria Tous-Ramón, Ulrich Steinbrecher, Luca Marotti, Matteo Nannini, Marwan Younis, Paco López-Dekker, Manfred Zink, Andreas Reigber, Gerhard Krieger, Alberto Moreira

Microwaves and Radar Institute (HR)German Aerospace Center

Microwaves and Radar Institute > Februar 2010 July 26th, 2011Slide 2Microwaves and Radar Institute

TanDEM-X as a Technological Challenge

VU 2 > Alberto Moreira

Experiments

SpotlightStripmap

ScanSARTOPS

Technological challenge:

monostatic TerraSAR-X sensing bistatic

TanDEM-X sensing


VU 3 > Alberto Moreira

Capabilities of TanDEM-X

TanDEM-X is a highly flexible sensor which enables multiple powerful imaging modes

Cross-Track Interferometry Along-Track Interferometry New Techniques

Digital Elevation Models

Spatial Coherence (forest, …)

Double DInSAR (change maps, ..)

High Resolution SAR Images

Large Scale Velocity Fields (ocean currents, ice drift, …)

Moving Object Detection

Temporal Coherence Maps

4 Phase Center MTI (traffic, …)

PolInSAR (vegetation height, …)

Digital Beamforming (HRWS, …)

Bistatic Imaging (classification, ..)

r+∆r r

t+∆t t

cross-track baselines(0 km to several km)

along-track baselines(0 km to several 100 km)

interferometric modes (bistatic, alternating, monostatic)

SAR modes(ScanSAR, Stripmap, …)

bandwidth / resolution(0 ... 150/300 MHz)

incident angles(20° ... 55°)

polarisations(single, dual, quad)

…


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 DEM 8 October (MET +115)

20 km


TanDEM-X First Bistatic AcquisitionBrasilia area


Stripmap acquisition (~3 m resolution)

100 MHz transmitted bandwidth

36.6 deg incident angle

Polarisation: VV

TanDEM-X (Second) First Bistatic ImageAlong-track

Bis

tati

c r

an

ge


TanDEM-X First Bistatic Acquisition: Bistatic vs Monostatic


Repeat-pass Interferometry

• 11-days lag

• 253 m cross-track baseline

• Mean coherence of 0.35

• Mean value for urban areas: 0.5

• Comparable performance

monostatic/monostatic


Repeat-pass Interferometry

• 11-days lag

• 253 m cross-track baseline

• Mean coherence of 0.35

• Mean value for urban areas: 0.5

• Comparable performance

bistatic/bistatic


What about Bistatic Single-pass Interferometry?

20 km

Doppler spectra

20 km

Spectral decorrelation!!


Single-pass Bistatic InSAR Experiment

20 km• 2 simultaneous monostatic

zD images

• 1 bistatic zD + 1 monostatic squinted

• 3 baselines: 2 half baselines (mo1/bi, mo2/bi) + 1 full baseline (mo1/mo2)


Single-pass Bistatic InSAR Experiment: Commanding

• Simultaneous bistatic and monostatic zD images!!!

• Solution: Alternating Bistatic operation (AltBi)!!!

• Problem: nominal AltBi does not consider pulse-to-pulse azimuth beams switching!!!

• TSX/TDX have two registered beam positions

• Second beam register used for Sync/Cal exchange

A bistatic single-pass interferometric

experiment was scheduled but with no data-

take dependent Sync/Cal information!!


Single-pass Bistatic InSAR Experiment: Implications

No Cal: no replica no corners/transponders, no cities


Automatic Synchronisation

• No Sync AutoSync

• Differential

• Iterative approach

• Based on the inversion of the bistatic image deformation map

• Accurate to a few degrees

• Implemented in TAXI: TanDEM-X Interferometric Experimental processor


TanDEM-X Single-pass Bistatic InSAR Experiment

Along-track

Bis

tati

c r

an

ge

M-TSX (zD)

M-TSX (sq)

B-TDX

M-TDX

• First bistatic single-pass interferometric acquisition (early October 2010)!!

• Performed over Costa Rica, close to Turrialba volcano

• Stripmap, 150 MHz, 35.8 deg incidence, HH pol

• Full-baseline HoA: 85 m



Pursuit monostatic

Single-pass bistatic

Pursuit monostatic

Single-pass bistatic



Monostatic DEM

Bistatic DEM

North


TanDEM-X Bistatic InSAR: AutoSync Validation

• Consistent with contemporary SyncLink measurements

• Estimated clock error rapidly decreasing after 2/3 iterations

• No trends

• of multilooked DEMdiff ~ 1m


Summary

• The first bistatic acquisitions were already performed during the pursuit monostatic commissioning phase with the system operated in non-nominal configurations and with an along-track baseline of 20 km

• First demonstration of spaceborne bistatic SAR imaging and bistatic interferometry


Future Past

…bistatic spotlight, dual-pol, AltBi…

More on TanDEM-X: Sessions WE1.T02, WE02.T02, WE03.T02, WE04.T02

More on Experiments with TanDEM-X: TH01.T01.3 (López-Dekker), TH01.T03.3 (Scheiber), FR01.T02.2(Prats)

first bistatic spaceborne sar experiments with tandem-x.ppt

Sports

bistatic single

bistatic zd

simultaneous bistatic

track bistatic range

bistatic vs monostatic

bistatic insar experiment

x vu alberto moreira

crosstrack baselines