7.7.2 TerraSAR-X-Add-on for Digital Elevation Measurements

Transcription

1 7.7.2 TerraSAR-X-Add-on for Digital Elevation Measurements TDX launched on June 21,

2 Overview of the TanDEM-X overall system architecture (image credit: DLR) Figure 10: Overview of the TanDEM-X overall system architecture (image credit: DLR) 19

3 DTED/HRTI Level Primary Mission Goal: Generation of a global HRTI-3 DEM 20

4 Standards for Digital Elevation Models Spatial Resolution Absolute Vertical Accuracy Relative Vertical Accuracy (90%) (point-to-point in 1 cell, 90%) DTED-1 90 m x 90 m < 30 m < 20 m DTED-2 30 m x 30 m < 18 m < 12 m TanDEM-X 12 m x 12 m < 10 m <2m Level-4 6mx6m <5m < 0.8 m Definition of 90% point-to-point errors: 1 1 relative height error h ~ absolute height error h single point errors (90% confidence interval) 2 h point-to-point errors (90% confidence interval) h 90% 2.33 h 21

5 TanDEM X HRTI-3 Spezification relative vertical accuracy 2 m (90% linear point-to-point error over 1 x 1 cell), absolute vertical accuracy 10 m (90% linear error), absolute horizontal accuracy 10 m (90% circular error), post spacing 12 m x 12 m TanDEM-X provides a configurable SAR Interferometry Platform for Demonstrating new SAR Techniques & Applications 22

6 Comparison of DTED/HRTI-Levels: Example DTED-2 SRTM / X-SAR HRTI-3 E-SAR 23

7 Ätna 24

8 SRTM TanDEM-X Coal Mine Hambach - Germany 25

9 Ziel der TanDEM-X-Mission: Dreidimensionale Vermessung der gesamten Erdoberfläche,150 Millionen km2 als Grundlage für ein breites Anwendungsspektrum: Umweltforschung, Entwicklung moderner Navigationssysteme etc. Beispiel für die extremen Anforderungenxtreme Anforderungen Aufnahmezeit im Orbit auf drei Minuten limitiert wegen Überhitzug des Satelleiten. Das globale Geländemodells erfordert weitere 30 Sekunden. Das erbrachte bereits in der Planung eine Simulation mit exakter Modllierung des Satelliten Aracar Vulkan im chilenisch-argentinischem Grenzgebiet 26

10 TanDEM-X an HR-driven Mission Internal operational Control System (IOCS) extensions TanDEM-X Acquisition Planner defines Helix parameters generates acquisition timeline on data take level including the thermal balance, etc. Bistatic commanding including synchronization pulse exchange Definition of exclusion zones and sync warning opportunities Step 1: First acquisition timeline DT DL DT DL TanDEM -X limit Feasible acquisitions Timeline (1 year) Step 2: Detailed Planning TanDEM -X limit Recalc. with real timing Timeline (1 year) Satellite memory consumption DL DT Satellite memory consumption Satellite memory consumption DT Step 3: Performance optimization TanDEM -X limit Performance optimized Timeline (1 year) DT in Orbit principally allowed during 3 min only due to heating up the Satellite Necessary 30 sec more Exact Simulation of the Temperature Profile leads to respective gain 27

11 TanDEM-X an HR-driven Mission Definition of interferometric modes Pursuit Monostatic both satellites transmit and receive independently temporal decorrelation & atmospheric disturbances backup solution Bistatic Alternating Bistatic one satellite transmits and both satellites receive simultaneously transmitter alternates between PRF pulses dual use of signal energy enables synchronisation, calibration & verification requires synchronisation provides two baselines Design of the synchronisation system and of algorithms for evaluating synchronisation pulses 28

12 Previous Civilian SAR Sensors 20 m Resolution TerraSAR-X 1 m Resolution 29

13 TanDEM-X an HR-driven Mission Mission proposal initiated jointly with Astrium (PI: A. Moreira) Scientific user requirements established (more than 100 scientists involved) Coordination of more than 700 scientists from 35 countries (>15000 requests in response to the 1st AO) Cross-Track Interferometry Along-Track Interferometry r+ r r t+ t Digital Elevation Models Spatial Coherence (forest, ) New Techniques t Large Scale Velocity Fields (ocean currents, ice drift, ) 4 Phase Center MTI (traffic, ) PolInSAR (vegetation height, ) Double DInSAR (change maps,..) Moving Object Detection Digital Beamforming (HRWS, ) High Resolution SAR Images Wolfgang Keydelel, DLR Microwaves and Radar Institute, Vorlesung Temporal Coherence Maps Bistatic Imaging (classification,..)30

14 TanDEM-X an HR-driven Mission Helix formation - patented by HR 31

15 Tandem-X Elliptical Helix Orbit Configuration 32

16 TanDEM-X an HR-driven Mission Mutual Irradiation Exclusion Zones TSX may not transmit in asc. orbit 65 H EL IX TDX TSX DEM TSX 50 exclusion zones 30 TDX (example) 0 DEM TSX side-lobes exclusion zone all beam main lobes defined by IOCS TDX TDX may not transmit in desc. orbit 33

17 TanDEM-X an HR-driven Mission Calibration of the bistatic Interferometer Baseline Calibration: TSX estimation of baseline bias by dedicated data takes in near and far range USO 200 USO LAA Sync Link TRM Internal Calibration Star Tracker DGPS TSX CE CE LAA Internal Calibration TRMs GPS m- TDX TDX m SAR Antenna Internal calibration Nominal calibration points Baseline Calibration pulses only Interpolated curve Instrument Phase Calibration: - calibration pulse measurement - SAR antenna phase pattern 34

18 TanDEM-X an HR-driven Mission Delay Calibration enables resolving 2 -ambiguity intervall using radargrammetry - residual internal delay differences - relativistic effects - bandwidth dependency - sync horn dependency - receiver gain dependency radial rbi 300 m [mm] TDX TSX 600 m alongtrack TSX Master 10 arglat TDX Master rbi B vs 14mm (B 600m) c Ambiguity Interval all delays successfully calibrated radargrammetry works! 35

19 TanDEM-X an HR-driven Mission Performance Monitoring Mean offset to SRTM for 89% of all processed scenes within ±10m 36

20 TanDEM-X an HR-driven Mission Acquisition Schedule Commissioning Phase 1 global DEM acquisition with small baselines + acquisition of scientific radar data products t months 6 months 1 global DEM acquisition with scaled (larger) baselines + acquisition of scientific radar data products DEM data takes for difficult terrain with different viewing geometry + radar data products radar data products and high res. DEMs with large interferometric baselines Mid 2014: DEM processing finished (90%) 37

21 Summary The Institute plays a central role in TerraSAR-X. TanDEM-X mission proposal initiated by the Institute jointly with Astrium. The Institute was the driving force in the design, implementation and is leading operation and scientific exploitation of TanDEM-X. Combining SAR system engineering, calibration and verification, and the development of the IOCS are key factors to the success of the missions. TanDEM-X is a milestone in remote sensing and demonstrates Germany s expertise in spaceborne radar technology. Programmatic continuity was a precondition to reach this level and has to be guaranteed in the future. 38