合成孔径雷达概念课件

第二章.ConceptofSAR（合成孔径雷达概念）第二章.ConceptofSAR（合成孔径雷达概念）1RadarResolution（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.RadarResolution（分辨率）Rangeres2RangeResolution（距离分辨率）

Antenna

FlightdirectionAzimuthdirection

q

D

RangedirectionSlantrangedirectionSlantrange（斜距）Range（距离）RangeResolution（距离分辨率）3RangeResolution（距离分辨率）Whenusingpulsecompressiontechnique脉冲压缩技术

Antenna

FlightdirectionAzimuthdirection

q

D

RangedirectionSlantrangedirectionBR:ChirpbandwidthRangeResolution（距离分辨率）Whenu4Example:Pulselength=0.1milli-seconds,lookangle=30oR’r=0.1x10-3x3x108/2=15kmRr=R’r/sin(30o)=30kmUsingrangecompressionmethod:Example:Usingrangecompressio5AzimuthResolution（方位分辨率）

Azimuthresolutionofrealapertureradar真实孔径雷达的方位向分辨率

Antenna

FlightdirectionAzimuthdirection

q

D

RangedirectionSlantrangedirectionAzimuthResolution（方位分辨率）Azi6SAR（合成孔径雷达）Throughthemovingofantennaalongaline,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，形成一根很长的天线，从而改善分辨率SAR（合成孔径雷达）Throughthemoving7SketchMap（示意图）(FromGlobeSARprogram,CCRS)SketchMap（示意图）(FromGlobeSAR812Shifttowardshigherfrequency34ShifttowardslowerfrequencyDecompositionofMultipleImaging

（多次成像分解示意图）12Shifttowardshigherfrequen9舒宁等1997舒宁等199710SynthesisofMultipleImaging（合成）ObjectsexperienceilluminationoveratimeintervalRecordandsavethecompletehistoryofreflections（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,theazimuthresolutioncanbesharpened(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）SynthesisofMultipleImaging（11(Courtesy:CCRS)(Courtesy:CCRS)12(Courtesy:CCRS)(Courtesy:CCRS)13ForERS-1/2,a10mantennaisusedtosynthesizeanearly5kmantenna.About1000radarimagesareusedtogetoneSARimage.ForERS-1/2,a10mantennais14RenewedAzimuthResolution

(更新的方位分辨率)Syntheticapertureradar（合成孔径雷达）RenewedAzimuthResolution

(更新15Example:ERS-1/-2SARResolutionAntennalength:L=10mTypicalrange:Groundrangeresolution:Azimuthresolution:Example:ERS-1/-2SARResoluti16(Crimea,Ukraine)RealApertureRadarS