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.