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Abstract - KNU and KIGAM are developing a ground-based Arc-scanning SAR system (ArcSAR) mounted on a truck. The system achieves a coherent integration of radar returns from ground targets by the circular motion of the antennae attached to the end of an extendable arm. Precise control of antenna position and the extended coherent-integration-length enable the formation of high-resolution, high-precision and phase-preserving SAR images. Deramp-FFT algorithm was used for ArcSAR Spot Mode focusing while Range-Doppler algorithm was implemented for ArcSAR Scan Mode, both in polar format. ArcSAR Spot Mode has 3.14 times higher resolution than GB-SAR, while ArcSAR Scan Mode can obtain omnidirectional image with reduced resolution but still has 11 times higher resolution than a conventional real aperture radar.

A Ground-Based Arc-Scanning Synthetic Aperture Radar (ArcSAR) System and Focusing Algorithms

Hoonyol LeeDepartment of Geophysics, Kangwon National University, Chuncheon, Republic of Korea (hoonyol@kangwon.ac.kr)

Seong-Jun Cho and Kwang-Eun KimKorea Institute of Geosciences and Mineral Resources, Daejeon, Republic of Korea (mac, kimke@kigam.re.kr)

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GB-SAR

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

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ArcSAR System

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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

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Deramp Function:

Azimuth Compression: IFFT

Focused Image:

Azimuth (angular) Resolution:

Phase:

ArcSAR FocusingSPOT Mode : Deramp-FFT Algorithm

Deramp-FFT Algorithm in Polar FormatRange Compressed Signal:

Coherent Integration Arc:

Range Function:

Taylor’s Expansion at :

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Range-Doppler Algorithm in Polar FormatRange Compressed signal:

Coherent Integration Arc:

Range Function:

Taylor’s Expansion at :

Matched Filter:

Azimuth Compression: Matched Filtering

Focused Image:

Azimuth (angular) Resolution:

Phase:

ArcSAR FocusingSCAN Mode : Range-Doppler Algorithm

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ArcSAR Focusing 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

SPOT: Deramp-FFTSCAN: Range-Doppler

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Azimuth Resolutions

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Simulation: ArcSAR Spot Mode

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Simulation: ArcSAR Scan Mode

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ArcSAR Scan Mode Experiment

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Conclusions

A novel ArcSAR system is developed and mounted on a truck.

Deramp-FFT algorithm was used for the ArcSAR Spot Mode.

Range-Doppler algorithm was implemented for the 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 Scan Mode > ArcRAR 167.2 53.4 11.0 1

ArcSAR Spot Mode has 3.14 times higher resolution than GB-SAR.

ArcSAR Scan Mode can obtain omnidirectional image with reduced resolution, but still has 11 times higher resolution than a conventional real aperture radar.

The system will provide a rapid response tool for various applications such as regional mapping and environmental hazard monitoring.