Engineering geophysics Agenda Introduction of SAR and GBSAR

Engineering geophysics Agenda • • • Introduction of SAR and GB-SAR Hardware configuration of GB-SAR Acquisition software for GB-SAR Focusing and Interferometry Feasibility test Conclusion KIGAM

Engineering geophysics Radar Radio Detection and Ranging WW II, US army. 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) KIGAM

Engineering geophysics 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 KIGAM

Engineering geophysics SAR(Synthetic Aperture Radar) Aperture: £Optics : Diameter of the lens or mirror. The larger the aperture, the more light a telescope collects. • 2. 4 m Hubble Space Telescope • 10 m Keck, Hawaii • 16. 4 m VLT (Very Large Telescope), Chile • 50 m Euro 50 (extremely large T. ) • 100 m OWL (Over. Whelmingly Large T. ) KIGAM £Euro 50

Engineering geophysics Real vs. Synthetic Aperture • Real Aperture : £ resolution ~ Rλ/L • Synthetic Aperture: £ resolution ~ L/2 £ Irrespective of R KIGAM

Engineering geophysics 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 KIGAM

Engineering geophysics SAR Focusing – Point Target azimuth range £original £After migration KIGAM £After range compression £After azimuth compression

Engineering geophysics • GB-SAR: Ground-Based Synthetic Aperture Radar – Synthetic Aperture Radar • Imaging Radar • Azimuth aperture synthesis – Ground-Based • Fairly versatile system configuration – Multiple frequency (L, C, X, Ku, Ka, etc) – Full Polarization (VV, VH, HV, HH) • Ultimate SAR focusing – Zero Doppler centroid (stationary vehicle during Tx/Rx) – Accurate estimation of Doppler rate from geometry • Topography Mapping: Cross-Track In. SAR or Delta-K In. SAR • Surface Motion: Zero-baseline and short atmospheric path for Temporal Coherency, DIn. SAR and PSIn. SAR • Useful for new SAR concept design KIGAM

Engineering geophysics State of the art of GB-SAR • LISA SAR (Italy) • GB-POLIn. SAR (Australia) • GB-SAR (Japan) KIGAM

Engineering geophysics KIGAM GB-SAR System(KIGAM-KNU)

Engineering geophysics KIGAM System Configuration

Engineering geophysics VNA(Vector Network Analyzer) §Stepped frequency §Both of Tx and Rx §Flexibility KIGAM

Engineering geophysics Antenna H-Pol radiation pattern Frequency(GHz) 5. 0~5. 6 E-Plane(deg) 15(nominal) 12. 1~13 H-Plane(deg) 15(nominal) 15. 5~17. 5 Gain(d. Bi) 20(nominal) 20. 5 min. (20. 5~21. 8) VSWR 1. 5 max. 1. 4 max. Isolation 35 d. B 이하 50 d. B 이하 Weight(kg) 4 max. 3. 1 max. Beam Width Dual-Polarimetric Square Horn Antenna KIGAM

Engineering geophysics Rail and motion control £ 2축 motion £ 6 m rail (2 m X 3) £Home and limit switch £Micro step motor £측정장치 일체형 £NI motion controller KIGAM

Engineering geophysics Amp and RF switch £Operating Freq. : 2~6 GHz £Power Gain: 34 d. B £ Maximum input: 6 d. Bm £Operation Freq. : ~20 GHz £GPIB interface £ 3중 1 X 2 SPDT KIGAM

Engineering geophysics Acquisition software Callibration Start Initialize all system Move to start position Acquisition Call cal: VV: Switching: Call cal: VH: Switching: Call cal: HV: Switching: Call cal: HH: Switching Save data Move or Stop KIGAM End

Engineering geophysics SAR Focusing Algorithms Advantage Disadvantage Usage Range-Doppleror ω-k Widely used for SAR Memory inefficiency for partial-focusing Near Range (full-focusing) Deramp-FFT Efficient in Far Range Distortion in near memory and CPU range (partial-focusing) time Time Domain Exact everywhere Time consuming KIGAM Everywhere

Engineering geophysics GB-SAR Resolutions Range resolution: (a) Full Focusing KIGAM (b) Partial Focusing

Engineering geophysics GB-In. SAR Configuration • • DIn. SAR Cross-Track In. SAR Delta-K In. SAR Cross-Track and Delta-K In. SAR £DIn. SAR with range change £Cross-Track KIGAM In. SAR

Engineering geophysics KIGAM Test • T 1 Range: Center frequency=5. 3 GHz Bandwidth=200 MHz Sample=1601 Power=33 d. Bm (2 W) Azimuth: Scan length=5 m Step=5 cm Sample=101 • T 2: Temporal baseline of 20 minutes (DIn. SAR) • T 3: Spatial baseline of -30 cm vertical (In. SAR DEM) • T 4: Frequency shift of -10 MHz (Delta-K In. SAR) KIGAM

Engineering geophysics Image Area KIGAM

Engineering geophysics VV KIGAM

Engineering geophysics VH KIGAM

Engineering geophysics DIn. SAR (T 2 -T 1) VV KIGAM

Automatic Acquisition with 2 cm Step, 2007. 3. 19 7: 22 pm- 4: 20 am, A 1~A 9 Engineering geophysics HH VV KIGAM

Engineering geophysics • • • A GB-SAR system was developed, tested, and waiting for applications. Optimal GB-SAR focusing algorithms were tested. Cross-Track and Delta-K In. SAR were tested. DIn. SAR or PSIn. SAR were tested: Phase stability of 1° (0. 1 mm range) was achieved for several hours for stable reflectors, rendering phase change of 10 ° meaningful (1 mm range accuracy for DIn. SAR). GB-SAR can be used for various applications such as: – – • Conclusion Safety monitoring of geohazard area Safety monitoring of artificial structure Microwave backscattering properties of target New SAR system concept design More robust GB-SAR system optimized to a specific application will be developed. ->accurate positioning, cost effective system KIGAM