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S ynthetic ? A perture ? R adar !

강원대학교 자원개발연구소 세미나 – 2004 년 4 월 8 일. S ynthetic ? A perture ? R adar !. Systems and Signal Processing. 이 훈 열 강원대학교 지구물리학과. Synthetic Aperture Radar – Systems and Signal Processing. Radarrr rr rrr r rr r . Radio Detection and Ranging WW II, England. Military use

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S ynthetic ? A perture ? R adar !

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  1. 강원대학교 자원개발연구소 세미나 – 2004년 4월 8일 Synthetic?Aperture?Radar! Systems and Signal Processing 이 훈 열 강원대학교 지구물리학과

  2. Synthetic Aperture Radar – Systems and Signal Processing Radarrr rr rrr r rr r • Radio Detection and Ranging • WW II, England. Military use • measure backscattered amplitude and distance to target • High power, sharp pulse -> low power, FM-CW chirp signal • Navigation radar • Weather radar • Ground Penetrating Radar • Imaging radar • cf) LIDAR (Light detection and Ranging)

  3. Synthetic Aperture Radar – Systems and Signal Processing Imaging Radar Different Eyes microwave, UHF, VHF surface roughness and dielectric constant Microwave Ranging All-weather Cloud-free Side-looking Active System Day and night imaging independent of solar illumination

  4. Synthetic Aperture Radar – Systems and Signal Processing Aperture Optics : Diameter of the lens or mirror. The larger the aperture, the more light a telescope collects. Greater detail and image clarity will be apparent as aperture increases. 2.4m Hubble Space Telescope 10m Keck, Hawaii 16.4m VLT (Very Large Telescope), Chile 50m Euro50 100m OWL (OverWhelmingly Large T.)

  5. OverWhelmingly Large Telescope

  6. Synthetic Aperture Radar – Systems and Signal Processing Real Aperture vs. Synthetic Aperture • Real Aperture : • resolution ~ Rλ/L • Synthetic Aperture: • resolution ~ L/2 • Irrespective of R • Smaller, better?! • - Carl Wiley (1951)

  7. Synthetic Aperture Radar – Systems and Signal Processing Image Acquisition ERS–1/2 SAR L: 10 m, D: 1 m Altitude: 785 km, sun-synchronous orbit Ground Velocity: 6.6 km/s Look Angle: Right 17-23 (20.355 mid-swath) Slant Range: 845 km (mid-swath) Frequency: C- Band (5.3GHz, 5.6 cm) Footprint : 100 km x 5 km Incidence Angle: 19  – 26  (23  mid-swath) Sampling Rate: 18.96 MHz Pulse duration: 37.1 s Range gate: ~ 6000 s Sampling Duration: ~ 300 s (5616 samples) Inter-pulse period: ~ 600 s ( upto 10 pulses) Pulse Repetition Frequency: 1700 Hz Data Rate: 105 Mb/s (5 bits/sample)

  8. Synthetic Aperture Radar – Systems and Signal Processing SAR Systems Spaceborne SAR SEASAT-A (USA, 1978), SIR-A (USA, 1981), SIR-B (USA, 1984), SIR-C/X-SAR (USA, Germany, Italy, 1994), ALMAZ-1 (Russia, 1991-1993), ERS-1(EU, 1991-2000), ERS-2 (EU, 1995-), JERS-1 (Japan, 1992-1998), Radarsat-1 (Canada, 1995-), SRTM (USA/Germany, 2000), ENVISAT (EU, 2002), RADARSAT-2 (Canada, 2005), PALSAR (Japan, 2004), LightSAR (US)*, TerraSAR (Germany)*, MicroSAR(EU)* Airborne SAR TOPSAR (JPL, USA), IFSARE(ERIM/Intermap, USA), DO-SAR(Donier,Germany), E-SAR(DLR, Germany), AeS-1(Aerosensing, Germany), AER-II (FGAN, Germany), C/X-SAR (CCRS, Canada), EMISAR (Denmark), Ramses (ONERA, France), ESR (DERA, UK) Planetary SAR Magellan (US, 1990-1994), Titan Radar Mapper (US, 2004), Arecibo Antenna, Goldstone antenna * Under development

  9. Synthetic Aperture Radar – Systems and Signal Processing SAR System Modes • Target – the Earth or planets • Vehicle – stationary, airborne, satellite, or spaceship • Mode – monostatic and/or bistatic • Carrier frequency – X, C, S, L, and/or P bands • Polarisation – HH, VV, VH, HV (single-pol, dual-pol, full-pol) • Imaging geometry – strip, scan, spot • <examples> • SIR-C/X-SAR: space shuttle, mono, L/C/X, full-pol. • ERS-1/2, Envisat: Earth satellite, mono, C, VV. • SRTM: space shuttle, mono/bistatic, C/X, HH/VV. • Arecibo Antenna: planetary, stationary, mono/bi, multi-bands, multi-pol. • Magellan, Cassini SAR: Venus and Titan, mono, S, HH. • AIRSAR/TOPSAR: airborne, mono/bi, L/C/P, full-pol

  10. Synthetic Aperture Radar – Systems and Signal Processing ENVISAT Launched 2002.2.28 C-band, Multpol, multi-mode Data : Envisat Announcement of Opportunity

  11. Synthetic Aperture Radar – Systems and Signal Processing Image Domain Range (R) 5616 pixels, 100 km Azimuth (s) 28,000 lines, 106 km

  12. Synthetic Aperture Radar – Systems and Signal Processing Range Compression Linear Chirp Signal Chirp autocorrelation Function Matched Filtering For ERS-1/2, Pulse duration (T): 37.1 s Bandwidth : 15.5 MHz Half power width of autocorrelation function: 0.065 s Pulse Compression Ratio: 575 (ERS-1/2) Ground Range Resolution: 12.5 m Input Range FFT Range Matched Filtering Range iFFT

  13. Synthetic Aperture Radar – Systems and Signal Processing Flight Path Point Target Range Migration Quadratic (Range Curvature) Linear (Range Walk) Azimuth FFT

  14. Synthetic Aperture Radar – Systems and Signal Processing Range Migration Compensation Range (R) Azimuth (s) After Range Walk Compensation Range Migration

  15. Synthetic Aperture Radar – Systems and Signal Processing Azimuth Compression Synthetic Aperture Real Aperture Doppler Shift (Linear Chirp Pulse) : wavelength L: Antenna length For ERS-1/2, Coherent Integration Time (S): 600 ms (5 km footprint) Bandwidth: 1260 Hz Half power width of autocorrelation function: 0.8 ms Pulse Compression Ratio: 756 (ERS-1/2) Azimuth Resolution: 5 m Azimuth footprint width: 5 km (ERS-1/2) Matched Filtering Azimuth Matched Filtering Output

  16. SAR Focusing – Point Target azimuth range original After range compression After migration After azimuth compression

  17. Synthetic Aperture Radar – Systems and Signal Processing Southeast Cost of Spain ERS-2 (13km x 13km) Descending, Right Looking

  18. Synthetic Aperture Radar – Systems and Signal Processing Geometric Distortion Terrain Imaging Geometry Foreshortening Layover Shadow

  19. Synthetic Aperture Radar – Systems and Signal Processing Scattering Mechanisms

  20. Synthetic Aperture Radar – Systems and Signal Processing Rule of Thumb in SAR images • Backscattering Coefficient • Smooth – Black • Rough surface – white • Calm water surface – black • Water in windy day – white • Hills and other large-scale surface variations tend to appear bright on one side and dim on the other. • Human-made objects - bright spots (corner reflector) • Strong corner reflector- Bright spotty cross (strong sidelobes)

  21. Synthetic Aperture Radar – Systems and Signal Processing 청주공항 (ERS-2)

  22. Synthetic Aperture Radar – Systems and Signal Processing Aleutian Volcanic Islands (ERS-1)

  23. Synthetic Aperture Radar – Systems and Signal Processing Ship Wakes over the Bering Sea The Calving of Iceberg A-38 (ERS-1 46 km x 28km)

  24. Synthetic Aperture Radar – Systems and Signal Processing 대청호 ERS-1/2 SAR Calm Water Rough Water

  25. Synthetic Aperture Radar – Systems and Signal Processing Ronne Ice Shelf, Antarctica The Calving of Iceberg A-38 (Radarsat ScanSAR 150km x 150km)

  26. 4-inch SAR onboard UAV

  27. Synthetic Aperture Radar – Systems and Signal Processing SAR Advanced Techniques • Radarclinometry: DEM from Shape-from-shading (experimental) • Radargrammetry: DEM from stereo SAR image matching (m) • InSAR: • Interferogram: DEM (cm) • Coherence: statistical measurement of temporal and spatial decorrelation (cm) • DInSAR: surface displacement, penetration depth (mm). • Pol-SAR: Classification, segmentation • Pol-InSAR: measurement of scattering structure • SAR Tomography: 3D target distribution

  28. Synthetic Aperture Radar – Systems and Signal Processing InSAR– Digital Elevation Model ERS-1/2 Tandem Interferogram

  29. InSAR Coherence Imagery Random Change Detection InSAR Coherence Image Optical Image

  30. InSAR Coherence Imagery Seismic Survey Lines

  31. Differential InSAREarthquake

  32. DInSAR Volcano

  33. DInSAR Glacier Velocity

  34. DInSAR Land Subsidence

  35. Planetary SARMagellan to Venus

  36. Planetary SARCassini to Titan

  37. Synthetic Aperture Radar – Systems and Signal Processing SAR Applications for Peace • reconnaissance, survelliance and targetting • target detection and recognition • moving target detection • navigation and guidence - Sandia National Lab. 4-inch SAR

  38. Synthetic Aperture Radar – Systems and Signal Processing SAR Peaceful Applications • Cartography – DEM, DTM • Geology – Geological Mapping • Seismology – Co-seismic displacement field • Volcanology – Prediction of volcano eruption • Forestry – Forest classification, deforest monitoring • Soil Science – Soil moisture • Glaciology – Glacier motion • Oceanography – Ocean wave, wind, circulation, bathymetry • Agriculture – Crop monitoring • Hydrology – Wetland assessment • Environment – Oil spill, hazard monitoring • Archaeology – Sub-surface mapping

  39. Synthetic Aperture Radar – Systems and Signal Processing Korean SAR

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