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Development of Focusing Algorithms for Arc-scanning
Ground-Based Synthetic Aperture Radar
Hoonyol LeeDept. of Geophysics, Kangwon National
University
Seong-Jun Cho and Kwang-Eun KimKorea Institute of Geosciences and Mineral
Resources
ISRS2009, Haeundae Grand Hotel, Busan, Korea, 28-30 October, 2009
Contents
Introduction to ArcSARFocusing Algorithms for ArcSAR Spot and Scan ModesComparison of Resolutions ArcSAR Spot Mode, ArcSAR Scan Mode,
Linear-scanning GBSAR, and a conventional radar (ArcRAR)
ResultsConclusions
Introduction to ArcSAR
GB-SAR(KIGAM-KNU)
DInSAR tested: Phase stability of 1° (0.1mm range) was achieved for several hours for stable reflectors, rendering phase change of 10 ° to be assured (1mm accuracy).
PSInSAR displacement measurement: R2=0.9999 achieved.
GB-SAR can be used for various applications such as:Safety monitoring of natural or anthropogenic structuresMicrowave backscattering properties of targetNew SAR system concept design
ArcSAR Concept
AWSAWS
ArcSAR RF Configuration
ArcSAR Design
Circular Rail and Extendable Boom
ArcSAR Truck
ArcSAR Leveler
ArcSAR Leveler
ArcSAR Data Acquisition
GB-SAR vs ArcSARGB-SAR ArcSAR(World first)
Scan Type Linear Arc
Polarization Full Full
Scan Load Heavy Light
Azimuth Resolution High3 times Higher than GB-SAR
Installation Ground-fixedAutomobile: higher mobility
Motion ControlSimple (linear motion)
Complex (2 rotational motions)
SAR focusing Conventional New
Major applicationDInSAR change detection
Emergency MappingDInSAR change detection
ArcSAR Focusing Algorithms
ArcSAR Geometry
Polar Imaging Domain: Range
and “True” azimuth
ArcSAR Imaging Modes
Spot Mode Dual rotational motion (boom
and antenna) Coherent Integration Arc can
be 180 degree maximum. High resolution Limited azimuth coverage
Scan Mode Single rotational motion
(boom only) Coherent Integration Arc is
the width of the antenna beam.
Low resolution Full azimuth coverage
ArcSAR Focusing
Spot Mode Deramp-FFT Algorithm in
Polar Format Range Compressed Signal:
Coherent Integration Arc:
Range Function:
Scan Mode Range-Doppler Algorithm
in Polar Format Range Compressed signal:
Coherent Integration Arc:
Range Function:
ArcSAR Focusing
Spot Mode Taylor’s Expansion
at :
Deramp Function:
Azimuth Compression: IFFT
Scan Mode Taylor’s Expansion
at :
Matched Filter:
Azimuth Compression: Matched Filtering
ArcSAR Focusing
Spot Mode Focused Image:
Azimuth (angular) Resolution:
Phase:
Scan Mode Focused Image:
Azimuth (angular) Resolution:
Phase:
Flowchart
Raw Data
Range Hamming Filter
Range Compression
Range Migration
Azimuth FFT
Multiply Deramp function
Azimuth Hamming Filter
Azimuth FFT
Range Migration
Azimuth Matched Filter
Azimuth Hamming Filter
Azimuth iFFT
Geometric Correction
Output
Geometric Correction
Output
Deramp-FFT Range-Doppler
Azimuth Resolutions
Results
Simulation: ArcSAR Spot Mode
Simulation: ArcSAR Scan Mode
ArcSAR Scan Mode Experiment
Further Research
A brand-new truck has arrived and is under reform.
Second motor control for ArcSAR Spot Mode will be added.
Integrated Controller
SAR, InSAR, Surface motion detector software
GPS, AWS
Increase Mileage!
Conclusions
Image focusing algorithms for ArcSAR were developed in polar coordinates.
The Deramp-FFT algorithm was used for ArcSAR Spot Mode and the Range-Doppler algorithm for ArcSAR Scan Mode.
Comparisons of image resolutions between various ground-based radar systems confirmed the advantages of ArcSAR:
ArcSAR Spot Mode > Linear-scanning GBSAR > ArcSAR Spot Mode > ArcRAR
167.2 53.4 11.0 1
The system will be mounted on a “new” truck and will provide a rapid response tool for various applications such as regional mapping and environmental hazard monitoring.