차량탑재형 arcsar 시스템 개념설계

KIGAMKIGAMKIGAMKIGAM

차량탑재형 ArcSAR 시스템 개념설계차량탑재형 ArcSAR 시스템 개념설계

2008. 3. 21. 2008. 3. 21. 대한원격탐사학회 춘계학술발표회 대한원격탐사학회 춘계학술발표회

1) 조성준 , 2) 이훈열 , 1) 김광은1) 한국지질자원연구원2) 강원대학교

Engineering geophysicsEngineering geophysics


Agenda

• 연구배경 및 목적• Introduction of GB-SAR• Concept of ArcSAR• Hardware configuration of ArcSAR• Imaging geometry of ArcSAR• 향후 추진 계획



연구배경 및 목적

• 레일형 GB-SAR 는 반복측정을 통해 mm 이내의 변형까지 감지할 수 있는 높은 분해능을 자랑

• 레일을 모니터링 위치에 고정시켜야 하는데 고정밀 레일의 제작비용이 매우 비싸며 , 측정장치의 운반과 설치 역시 매우 복잡

• 차량에 원형레일을 탑재하여 신속한 기동을 확보• 합성구경의 길이를 늘리며 영상영역을 확장한 Arc-

SAR 개발



GB-SAR

• 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 InSAR or Delta-K InSAR• Surface Motion: Zero-baseline and short atmospheric path for

Temporal Coherency, DInSAR and PSInSAR• Useful for new SAR concept design



SAR Focusing – Point Target

rang

e

azimuth

original After range compression

After migration After azimuth compression



State of the art of GB-SAR

• LISA SAR (Italy)• GB-POLInSAR (Australia)• GB-SAR (Japan)• Mobile SAR (Korea)



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



System Configuration

T X R X O U TINM o t io nC o n t ro l

GP IB

T x V - p o lT x H - p o l

R x H - p o lR x V - p o l



GB-SAR System(KIGAM-KNU)



SAR Focusing Algorithms

Algorithms Advantage Disadvantage Usage

Range-Doppler or ω-k

Widely used for SAR

Memory inefficiency for

partial-focusing

Near Range (full-focusing)

Deramp-FFTEfficient in

memory and CPU time

Distortion in near range

Far Range(partial-focusing)

Time DomainExact

everywhereTime

consumingEverywhere



ArcSAR Concept design

AWSAWS



GB-SAR vs ArcSAR

GB-SAR ArcSAR(World first)

Scan Type Linear Arc

Scan Load Heavy Light

RF stability Stable Stable

Resolution HighHigher due to wider azimuth bandwidth

Installation Ground-fixedAutomobile: higher mobility

Phase repeatability High Low (Still now)

SAR focusing Conventional New

Major applicationDInSAR change detection

Emergency Mapping(Still now)DInSAR change detection (future)



ArcSAR Hardware configuration

T X R X O U TIN

M o t io nC o n tro l

GP IB

T x V - p o lT x H - p o l

R x H - p o lR x V - p o l

T X R X

Exp re ss

R S - 2 3 2

S y n ch ro n o u sT u rn ta b le



VNA(Vector Network Analyzer)

Stepped frequencyBoth of Tx and RxFlexibility10 MHz – 20 GHz



Antenna

H-Pol radiation pattern

Dual-

Polarimetric

Square Horn

Antenna

Frequency(GHz) 5.0~5.6 5.0~5.6

Beam WidthE-Plane(deg) 15(nominal) 12.1~13

H-Plane(deg) 15(nominal) 15.5~17.5

Gain(dBi) 20(nominal) 20.5 min.(20.5~21.8)

VSWR 1.5 max. 1.4 max.

Isolation 35dB 이하 50dB 이하

Weight(kg) 4 max. 3.1 max.

Input Impedance(Ω) 50 50



Amp and RF switch

Operating Freq.: 2~6 GHzPower Gain: 34 dB Maximum input: 6 dBm

Operation Freq.: ~20GHzGPIB interface3 중 1X2 SPDT



Acquisition software

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

End

Move or Stop

Callibration

Save data



Design of a arc-rail



ArcSAR Standard Mode: 360˚ coverage with moderate resolution

ArcnIntegratioCoherent:

,Wavelength:

where

2:ResolutionAngular

s

s

L

λ

L



ArcSAR Spot Mode: Limited coverage with higher resolution

ArcnIntegratioCoherent:

,Wavelength:

where

2:ResolutionAngular

s

s

L

λ

L



향후 추진계획

• ArcSAR 레일 제작• 자료획득 프로그램 개발• ArcSAR 포커싱 알고리듬 개발• 획득 및 자료처리 프로그램 통합• 현장 테스트 (GB-SAR 와 비교실험 )• 위치보정 알고리듬 개발• 모니터링 테스트

차량탑재형 arcsar 시스템 개념설계

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