Polarisation Capabilities and Status of TerraSAR-X

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1 Polarisation Capabilities and Status of TerraSAR-X Irena Hajnsek, Josef Mittermayer, Stefan Buckreuss, Kostas Papathanassiou German Aerospace Center Microwaves and Radar Institute 26-Jan-2009

2 TerraSAR-X Satellite Wet mass: 1209 kg Orbit average power: 800 W Size: 5 m height 2.4 m diameter Thrusters Solar Generator X-Band Radar Antenna 384 Transmit/Receive Modules S-Band TM/TC Antenna X-Band Downlink Antenna Data Rate: 300 MBit/sec 256 Gbit Solid State Mass Memory Slide 2

TerraSAR-X Satellite Key Features High resolution in SpotLight

Multi-polarization capability Left Looking Mode (roll maneuver of

) 300 MHz transmit bandwidth (1 m range resolution) Reference

3 TerraSAR-X Satellite Key Features High resolution in SpotLight mode Possibility of large area coverage by utilizing ScanSAR mode Multi-polarization capability Left Looking Mode (roll maneuver of S/C) Dual Receive Antenna (DRA) Mode (ATI, MTI, Quad. Pol.) 300 MHz transmit bandwidth (1 m range resolution) Reference orbit with ±250 m orbit tube (repeated acquisitions, interferometry, etc.) Total Zero Doppler Steering Secure operation by encryption of commands and data downlink Prepared for TanDEM-X operation (synchronization) Slide 3

4 Munich Oktoberfest Site Januar Juni Institut für Methodik der Fernerkundung Differenz Slide 4

5 Data Quality Achievements Improvements Trends Plans Slide 5

6 Calibration: Results of the Commissioning Phase Goal: SAR product verification and release of the basic products Verification of format, annotation and content passed Updated basic product specification Improvements w.r.t. initial version as for example (Stripmap) o absolute radiometric accuracy: 1.1 db 0.6 db o relative radiometric accuracy 0.68 db 0.31 db o spotlight mode (azimuth) resolution 2.2 m 1.7 m o pixel localization accuracy 2.0 m 0.3 m in range 2.0 m 0.53 m in azimuth o side lobe ratio improved by approx. 10 db* *(at the cost of a reduction of the slant range resolution of 9 % from 1.1 m to 1.2 m) Slide 6

7 Dubai Stripmap VV-pol. 26. Juni April 2008 Difference Slide 7

8 High Resolution Spotlight Image of Anak Krakatau Improperly amplified DC-part of SAR image => range stripes Slide 8

9 High Resolution Spotlight Image of Anak Krakatau Spectral thresholding eliminates range stripes (improved replica implementation) Slide 9

10 Noise Correction in TerraSAR-X Processor TMSP noise pattern in low backscatter areas typical for ScanSAR results from azimuth and elevation antenna pattern correction for the individual bursts signal is perfectly calibrated but additional noise power is inhomogeneously distributed multiple superposition of statistical signal and noise distributions impairs some applications (e.g. ship detection) ScanSAR Sydney, Australia ( ) Slide 10

11 Noise Correction in TerraSAR-X Processor TMSP New SAR processor software is activated since Dec 1st, 2008 noise corrected product Slide 11

12 Calibration: Resumé after 1 Year of Operations No significant variation has been observed since launch! Instrument Stability: I/Q Statistic stable, no Trend TRM Monitoring (rel. ampl/phase): < 0.23 db / < 2.0 deg (1σ) Antenna Pattern Monitoring Shape within Main Beam Gain-Offset between different beams ±0.2 db (peak to peak) Radiometric Stability Requirement over 6 months 0.5 db (1σ) (requirement) Observed over 1 year 0.14 db Slide 12

13 Experimental Modes of TerraSAR-X Slide 13

14 TOPSAR Acquisition Mode TOPSAR is a modified ScanSAR mode: Ambiguity Reduction Scalloping Reduction TOPSAR Interferogram Slide 14

15 Bistatic Imaging Conducted on 5th of November 2007 TX with TerraSAR-X, RX with F-SAR Important preparation for TanDEM-X Clock synchronization In-orbit-phase-noise investigations Performance verification of bistatic processing and imaging techniques azimuth range Slide 15

16 Dual Receive Antenna Mode (DRA Mode) Transmit Receive Principle For transmit the full antenna is used For receive the antenna is electrically divided into two sections in azimuth direction two independent receive channels are available New Experimental Modes Along-Track Interferometry (ATI) (Moving Target Indication, Widespread Traffic Control, Ocean Current Measurement) Quad polarization (Sea/Ice, Snow Cover, Urban Environment) Quadpol switching scheme TX: V H V H RX 1 : V V V V RX 2 : H H H H CH 1 : VV HV VV HV CH 2 : VH HH VH HH Slide 16

17 Polarization Modes Single Polarization 1 polarization channel, {HH, VV} stripmap, spotlight, ScanSAR Dual Polarization 2 polarization channels, {HH/VV, HH/HV, VV/VH} stripmap, spotlight coherent pol. phase Twin Polarization 2 polarization channels, {HH/VV, HH/HV, VV/HV} stripmap incoherent pol. phase smaller elevation beam full elevation beam Quad Polarization All 4 pol. channels Stripmap coherent pol. Phase smaller elevation beam Experimental product H H H H H H H H H H H H H H H H H V H V H V H V H H V H V H V H V H H H H H H H H V V H H V V V V V V V H V Transmit Receive Transmit Receive Transmit Receive Transmit Receive Slide 17

18 First TerraSAR-X Quadpol Image! Workuta, Russia Stripmap June 23, 2008 red: HH-VV green: (HV+VH)/2 blue: HH+VV Slide 18

19 Polarimetric Analysis (dual pol X-Band RGB (hh+vv,hh,hh-vv) HHVV Coherence (amplitude) Slide 19

20 Polarimetric Analysis (dual pol HHVV) RGB (hh+vv,hh,hh-vv) HHVV Coherence (phase) Slide 20

21 Polarimetric Analysis (dual pol HHVV vs quad pol) RGB (hh+vv,hh,hh-vv) RGB (hh+vv,2hv,hh-vv) Slide 21

22 Dual Receive Mode Implementation (1) Decision to activate the redundant receive channel in March 08 Commanding of DRA mode was proved Instrument is capable to execute the DRA mode SAR Workflow is running well Manually(!) tuned quadpol product is available (June 08, IGARSS 08) Identified problems: Channel decoupling is problematic, on-ground characterization not sufficient New command structure w.r.t. additional cal pulses to be developed Commanding and processing to be iteratively optimized Slide 22

23 Dual Receive Mode Implementation (2) Work in progress: Presently test data takes are carried out and evaluated Review of results and final decision on way forward Calibration campaign (3 cycles) in spring 2009 (tbc) Final product release in summer 2009 (tbc) Quota limitation for future acquisitions to be discussed (Reliability calculation due to the use of redundancies) Slide 23

24 Status Summary Spacecraft and ground segment are fully operational Image products (Spotlight, Stripmap, ScanSAR) are calibrated and released Product quality within initial specification or better! SAR instrument proved to be very stable Demonstration of Repeat Pass Interferometry, Along Track Interferometry, persistent scatterer evaluation, TOPSAR, total zero Doppler steering Demonstration of quadpol mode The use of TerraSAR-X data was demonstrated for geo-scientific applications, oceanography and disaster monitoring during commissioning phase Preparation of TanDEM-X mission gains priority! Slide 24

TerraSAR-X Mission: Application and Data Access

TerraSAR-X Mission: Application and Data Access Irena Hajnsek & TSX TEAM German Aerospace Center Microwaves and Radar Institute Pol-InSAR Research Group 2 years in Orbit (since June 2007) irena.hajnsek@dlr.de