Monostatic Calibration of both TanDEM-X Satellites Marco Schwerdt   ,  Jaime Hueso Gonzalez , Markus Bachmann, Dirk Schran...
TSX-1 / TDX-1 In-Orbit Calibration Plan Operational Phase Ant Point Geo Cal GS/SC Checkout TSX-1 Launch  (15.06.2007) Radi...
TSX-1 Calibration
Geometric Calibration TSX-1 <ul><li>6 corner reflectors per pass </li></ul><ul><li>8 beams </li></ul>Near range  Far range...
Pointing Determination in Azimuth TSX-1 <ul><li>Updates </li></ul><ul><li>Improved ground receiver position </li></ul><ul>...
Antenna Pattern Monitoring TSX-1  <ul><li>ScanSAR-mode: several beams measured during one pass </li></ul><ul><li>Across an...
Antenna Pattern Long Term Monitoring TSX-1 Shape deviation within the main beam Beam-to-beam gain prediction stable, no tr...
Radiometric Calibration TSX-1 µ 2009  = -56.53dB + 0.10dB (CR) = -56.43dB µ ≤ ± 0.2dB within scene TerraSAR-X is extremely...
Calibration Tasks Performed in 2009 TSX-1 <ul><li>TerraSAR-X in Dual Receive Antenna (DRA) Mode </li></ul><ul><li>2 instru...
Channel Imbalance: Amplitude TSX-1 -0.18dB antenna gain Correction, V-pol on receive max. offset 0.44dB Channel imbalance ...
One-Way Cross Polar Isolation TSX-1 <ul><li>Ground receivers aligned for V-pol </li></ul><ul><li>1-way azimuth pattern mea...
TerraSAR-X Calibration Tasks Performed in 2009 C ALIBRATION  TerraSAR-X  is  stable  with  outstanding performance Slide 1...
TDX-1 Calibration
TDX-1 Calibration Goals <ul><li>TerraSAR-X calibration performance sets a solid basis </li></ul>≤   0.1dB /  ≤  1.0 degree...
TDX-1 Monostatic Calibration Strategy <ul><li>2.5 months (summer 2010) </li></ul><ul><li>Geometric calibration </li></ul><...
Calibration Field in South Germany near by Oberpfaffenhofen Munich D01 x D02 x D03 x D04 x D05 x D06 x D07 x D24-D30 x x x...
First Results: Chirp Comparison of TDX-1 – TSX-1 <ul><li>Receive pulses, BW = 150MHz, UP-chirp,  pulse length = 32µs </li>...
First results TDX-1: TRM Characterization – PN Gating blue: measured in flight cold red: measured in flight hot black: on ...
First Results TDX-1: Antenna Pattern over Rainforest <ul><li>Within requirements </li></ul>strip_003 strip_004 strip_005 s...
First Results TDX-1: Antenna Pattern by Ground Receivers  Ground Receiver Position Vector <ul><li>Measurements confirm sim...
First Sequential Ground Receiver Acquisition <ul><li>Direct measurement of the satellite separation in along track   Purs...
Questions? THE END TSX-1 DLR logo  experiment : Oberpfaffenhofen, Bayern, Germany (19 th  June 2008)
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TH1.L10.3: MONOSTATIC CALIBRATION OF BOTH TANDEM-X SATELLITES

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  • - the name was too long for the slide - Very homogenious, no logging paths, no deforestation, just pure rain forest
  • Antenna Excitation Generator : Berechnung der Anregungskoeffizienten , d. h. Amplituden- und Phasenbelegung =&gt; Schwenkung des Beams Einhaltung der Maske, Slope, Ripple Antenna Pattern Generator: Wie der Name schon sagt: Generiert der Antennenpattern. Problem nämlich: Umgebung auf Erde anders als im All, Gesamtantenne zu groß für Messkammer Optimale Vermessung der Antenna auf der Erde nicht möglich Antennenmodell um das Pattern möglichst genau nachbilden zu können Wofür? Prozessierung (PGS) -&gt; Rausrechnen der Antennencharakteristik aus dem Bild Da zwei getrennte Module =&gt; Zwei Assemblies =&gt; vor den Test cases : Überblick über Inputs/Outputs
  • Überleitung: - unabhängig von Position innerhalb des Swath - und vom jeweilighen Beam 1 Cal Faktor für alle Beams, d.h. der Cal Faktor kann aus allen Messungen die zur Re-Cal durchgeführt wurden abgeleitet werden und im Vergleich zu dem Cal-Faktor am Ende der CP, läßt sich die radiometrische Stabilität nach 2 Jahren erstmals aus realen Messungen ableiten
  • Nicht auf alle Punkte eingehen in 20min =&gt; daher Präsentation nur der wesentlichen Ergebnisse, insbesondere wo es Veränderungen gegeben hat! ICAL keine weiteren Auffälligkeiten =&gt; stabil, Top-Down Philosophie, solange absCal konstant, keine Notwendigkeit ICAL im Detail zu untersuchen
  • Nicht auf alle Punkte eingehen in 20min =&gt; daher Präsentation nur der wesentlichen Ergebnisse, insbesondere wo es Veränderungen gegeben hat! ICAL keine weiteren Auffälligkeiten =&gt; stabil, Top-Down Philosophie, solange absCal konstant, keine Notwendigkeit ICAL im Detail zu untersuchen
  • 29.07.10
  • TH1.L10.3: MONOSTATIC CALIBRATION OF BOTH TANDEM-X SATELLITES

    1. 1. Monostatic Calibration of both TanDEM-X Satellites Marco Schwerdt , Jaime Hueso Gonzalez , Markus Bachmann, Dirk Schrank, Clemens Schulz, Björn Döring
    2. 2. TSX-1 / TDX-1 In-Orbit Calibration Plan Operational Phase Ant Point Geo Cal GS/SC Checkout TSX-1 Launch (15.06.2007) Radiometric Calibration Ant Model Verification TSX-1 Commissioning Phase 5 Months Summer 2007 TDX-1 Comm. Phase TDX-1 Launch (21.06.2010) 5 Months (Mono + Bi: 3+2) Geo Cal Ant Point • • • • • • Channel Imbalance DRA Campaigns 1 Month Spring 2009 Radiometric Calibration Antenna Model Cross Talk Radiometric Calibration Ant Model Verification Geo Cal TSX-1 Re-Calibration 1 Month Ant Point Summer 2009 ≈ ≈
    3. 3. TSX-1 Calibration
    4. 4. Geometric Calibration TSX-1 <ul><li>6 corner reflectors per pass </li></ul><ul><li>8 beams </li></ul>Near range Far range - Azimuth shift - Instrument delay - Tropospheric effects <ul><li>Time annotation of source packets </li></ul><ul><li>Range delay </li></ul>Connection between SAR data and geographic position on Earth surface is calibrated 2m ( requirement ) 30 cm (1  ) (2 ns) <ul><li>Pixel localization accuracy (range) </li></ul>No trend since 2 years 3.75 cm (0.25 ns) <ul><li>Residual offset (in-flight  OGC) </li></ul>
    5. 5. Pointing Determination in Azimuth TSX-1 <ul><li>Updates </li></ul><ul><li>Improved ground receiver position </li></ul><ul><li>Re-adjustment between star trackers </li></ul><ul><li>Improvements 2007 2009 </li></ul><ul><li>Measurement accuracy ≤ 7.9 Hz ≤ 2.6 Hz (1  ) per pass < 1.0 mdeg < 0.33 mdeg </li></ul><ul><li>Mean doppler 16 Hz 5.9 Hz </li></ul><ul><li>Residual pointing error 2 mdeg 0.74 mdeg </li></ul><ul><li>Notch patterns with different look angles </li></ul><ul><li>4 ground receivers per pass </li></ul>Near range Elevation look angle [degree] Far range Frequency shift due to mispointing [Hz]
    6. 6. Antenna Pattern Monitoring TSX-1 <ul><li>ScanSAR-mode: several beams measured during one pass </li></ul><ul><li>Across an area of 750 x 750 km² </li></ul>Purpose Detect changes in the antenna front end and waveguides 120 km range 60 km azimuth strip_003 strip_004 strip_005 strip_006 Quality parameters *  max µ  min strip_003 strip_004 strip_005 strip_006
    7. 7. Antenna Pattern Long Term Monitoring TSX-1 Shape deviation within the main beam Beam-to-beam gain prediction stable, no trend Requirement still fulfilled Δ < ± 0.2dB
    8. 8. Radiometric Calibration TSX-1 µ 2009 = -56.53dB + 0.10dB (CR) = -56.43dB µ ≤ ± 0.2dB within scene TerraSAR-X is extremely stable 0.15dB over 2 years µ ≤ ± 0.2dB within full performance range Requirement 0.5 dB (1  ) over 6 months ! CR: corner reflector <ul><li>6 corner reflectors across the swath </li></ul><ul><li>3 beams (low, mid, high inc.) </li></ul>-57,6 -57,4 -57,2 -57 -56,8 -56,6 -56,4 -56,2 -56 -55,8 -55,6 10 15 20 25 30 35 40 45 Look Angle [deg] Abs Cal Factor [dB] strip_002 strip_007 strip_013  = -56.50 dB  = 0.21 dB  = -56.76 dB  = 0.24 dB  = -56.45 dB  = 0.16 dB strip_007 -57,6 -57,4 -57,2 -57 -56,8 -56,6 -56,4 -56,2 -56 -55,8 -55,6 Abs Cal Factor [dB] near mid far  = -56.73 dB  = 0.22 dB  = -56.65 dB  = 0.17 dB  = -56.62 dB  = 0.18 dB  = -56.67 dB  = 0.18 dB <ul><li>Radiometric Stability </li></ul> Abs. Cal Factor 2007 - 56.58 dB 2009 - 56.43 dB ≤ ± 0.2dB <ul><li>Antenna Model </li></ul>
    9. 9. Calibration Tasks Performed in 2009 TSX-1 <ul><li>TerraSAR-X in Dual Receive Antenna (DRA) Mode </li></ul><ul><li>2 instrument chains on receive (main and redundant) </li></ul><ul><li>2 antenna halves </li></ul><ul><li>Quad-pol mode </li></ul><ul><li>Along track interferometry </li></ul><ul><li>DRA Campaigns </li></ul><ul><li>Geometric calibration </li></ul><ul><li>Antenna model verification </li></ul><ul><li>Channel imbalance, phase </li></ul><ul><li>Channel imbalance, amplitude  radiometric calibration </li></ul><ul><li>Cross talk </li></ul>Ch. 2 Ch. 1
    10. 10. Channel Imbalance: Amplitude TSX-1 -0.18dB antenna gain Correction, V-pol on receive max. offset 0.44dB Channel imbalance 0.26 dB Abs. rad. accuracy during DRA campaigns 0.30 dB (1  ) (45° constellation)
    11. 11. One-Way Cross Polar Isolation TSX-1 <ul><li>Ground receivers aligned for V-pol </li></ul><ul><li>1-way azimuth pattern measured per pass </li></ul>Cross talk Requirement ≥ 24dB (1-way, StripMap) Receiver for V-pol Strip_013, des, Inc. 43.7° (16-04-2007) H V 1-way cross polar isolation (on transmit) > 34dB
    12. 12. TerraSAR-X Calibration Tasks Performed in 2009 C ALIBRATION TerraSAR-X is stable with outstanding performance Slide 12 27 DLR colleagues DRA mode calibration Radiometric stability 0.15 dB (over 2 years) Absolute radiometric accuracy 0.39 dB (StripMap) 0.46 dB (DRA Quad-pol) Channel imbalance 0.26 dB / < 3 deg Cross talk < - 24.9 dB 213 acquisitions 171 over rainforest 42 cal-field (306 targets) Re-calibration 2 years after launch Pointing accuracy < 1 mdeg (azimuth) < 4 mdeg (elevation) Pixel localization accuracy 31 cm (range) 54 cm (azimuth)
    13. 13. TDX-1 Calibration
    14. 14. TDX-1 Calibration Goals <ul><li>TerraSAR-X calibration performance sets a solid basis </li></ul>≤ 0.1dB / ≤ 1.0 degree Internal calibration accuracy < 0.7dB Absolute radiometric accuracy ≤ 0.5m (range/azimuth) Pixel localization accuracy ≤ 0.2 dB (requirement) Antenna model accuracy < 2 mdeg (azimuth) < 10 mdeg (elevation) Pointing accuracy TDX-1 Calibration Goals SAR Quality Parameter
    15. 15. TDX-1 Monostatic Calibration Strategy <ul><li>2.5 months (summer 2010) </li></ul><ul><li>Geometric calibration </li></ul><ul><li>Antenna pointing </li></ul><ul><li>Antenna model </li></ul><ul><li>Radiometric calibration StripMap and ScanSAR </li></ul>Cal test sites * Rainforest: distributed field * South Germany: 30 calibration sites from which 17 are permanently installed corner reflectors TanDEM-X calibration team 32 DLR colleagues Around 60 calibration campaigns with reference point targets: transponders and corners More than 1000 datatakes will be analyzed
    16. 16. Calibration Field in South Germany near by Oberpfaffenhofen Munich D01 x D02 x D03 x D04 x D05 x D06 x D07 x D24-D30 x x x x x x x D08 x D09 x D10 x D12 x D14 x D17 x D18 x D19 x D20 x D22 x D11 x D13 x D15 x D16 x D21 x D23 x 40km 120km S007 S007
    17. 17. First Results: Chirp Comparison of TDX-1 – TSX-1 <ul><li>Receive pulses, BW = 150MHz, UP-chirp, pulse length = 32µs </li></ul><ul><li>Similar spectrograms </li></ul>image frequencies chirp TSX-1 TDX-1 important for bistatic operation
    18. 18. First results TDX-1: TRM Characterization – PN Gating blue: measured in flight cold red: measured in flight hot black: on ground characterization Receive Phase [degrees] Amplitude [dB] Transmit Phase [degrees] Amplitude [dB] <ul><li>Warm instrument stability </li></ul>
    19. 19. First Results TDX-1: Antenna Pattern over Rainforest <ul><li>Within requirements </li></ul>strip_003 strip_004 strip_005 strip_006 strip_003 strip_004 strip_005 strip_006
    20. 20. First Results TDX-1: Antenna Pattern by Ground Receivers Ground Receiver Position Vector <ul><li>Measurements confirm simulated reference pattern </li></ul><ul><li>Within requirements </li></ul>Transmit pattern only Relative accuracy < ± 0.1dB
    21. 21. First Sequential Ground Receiver Acquisition <ul><li>Direct measurement of the satellite separation in along track  Pursuit monostatic phase </li></ul><ul><li>1 st absolute comparative measurement of transmitted power  <0.5dB difference TDX-1 – TSX-1 </li></ul>3s azimuth separation ≈ 20 km TSX-1 TDX-1 RX
    22. 22. Questions? THE END TSX-1 DLR logo experiment : Oberpfaffenhofen, Bayern, Germany (19 th June 2008)
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