合成孔径雷达概念课件.ppt

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1、第二章.ConceptofSAR（合成孔径雷达概念）RadarResolution（分辨率）Rangeresolution（距离向分辨率）--Rangeresolutionisdependentonthelengthofthepulse(脉冲长度);脉冲越短，分辨率越高。Azimuthresolution（方位向分辨率）--Azimuthresolutionisdeterminedbythebeamwidth（波束宽度）；波束越短，分辨率越高.RangeResolution（距离分辨率）AntennaFlight

2、directionAzimuthdirectionqDRangedirectionSlantrangedirectionSlantrange（斜距）Range（距离）RangeResolution（距离分辨率）Whenusingpulsecompressiontechnique脉冲压缩技术AntennaFlightdirectionAzimuthdirectionqDRangedirectionSlantrangedirectionBR:ChirpbandwidthExample:Pulselength=0.1m

3、illi-seconds,lookangle=30oR’r=0.1x10-3x3x108/2=15kmRr=R’r/sin(30o)=30kmUsingrangecompressionmethod:AzimuthResolution（方位分辨率）Azimuthresolutionofrealapertureradar真实孔径雷达的方位向分辨率AntennaFlightdirectionAzimuthdirectionqDRangedirectionSlantrangedirectionSAR（合成孔径雷达）Thr

4、oughthemovingofantennaalongaline,imageasceneforanumberoftimes。通过沿着一条直线移动天线，对同一地物多次成像Synthesizethemultipleimagingdataofascenetooneimage。把同一地物的多次成像合成为一幅图像Equivalentto“enlarge”theantenna,formingaverylongantennaandthusimprovingtheazimuthresolution等效于增大天线，形成一根很长的天

5、线，从而改善分辨率SketchMap（示意图）(FromGlobeSARprogram,CCRS)12Shifttowardshigherfrequency34ShifttowardslowerfrequencyDecompositionofMultipleImaging（多次成像分解示意图）舒宁等1997SynthesisofMultipleImaging（合成）ObjectsexperienceilluminationoveratimeintervalRecordandsavethecompletehisto

6、ryofreflections（记录和保存了完整回波信号）Permitsreconstructionofthereflectedsignals（反射信号重建）BasedontheprincipleofDopplerfrequencyshiftcausedbytherelativemovementbetweentheantennaandthetarget（依据多普勒频移原理）Bytracingthefrequencyshiftsandthussynthesisingthecorrespondingechoes,th

7、eazimuthresolutioncanbesharpened(SARfocusingtechnique)（根据多普勒频移，合成相应的回波，改善方位分辨率，称为SAR成像或聚焦过程）(Courtesy:CCRS)(Courtesy:CCRS)ForERS-1/2,a10mantennaisusedtosynthesizeanearly5kmantenna.About1000radarimagesareusedtogetoneSARimage.RenewedAzimuthResolution(更新的方位分辨率)S

8、yntheticapertureradar（合成孔径雷达）Example:ERS-1/-2SARResolutionAntennalength:L=10mTypicalrange:Groundrangeresolution:Azimuthresolution:(Crimea,Ukraine)RealApertureRadarSyntheticApertureRadar5x