合成孔径雷达概念ppt课件.ppt
第二章. Concept of SAR（合成孔径雷达概念）,Radar Resolution（分辨率）,Range resolution（距离向分辨率） -Range resolution is dependent on the length of the pulse(脉冲长度); 脉冲越短，分辨率越高。 Azimuth resolution（方位向分辨率） - Azimuth resolution is determined by the beam width（波束宽度）；波束越短，分辨率越高.,Range Resolution（距离分辨率）,Slant range（斜距）,Range（距离）,Range Resolution （距离分辨率）,When using pulse compression technique脉冲压缩技术,BR : Chirp bandwidth,Example:Pulse length = 0.1 milli-seconds, look angle = 30o Rr = 0.1 x 10-3 x 3 x 108/2 = 15 kmRr = Rr/sin(30o) = 30 km,Using range compression method:,Azimuth Resolution（方位分辨率）,Azimuth resolution of real aperture radar 真实孔径雷达的方位向分辨率,SAR（合成孔径雷达）,Through the moving of antenna along a line, image a scene for a number of times。通过沿着一条直线移动天线，对同一地物多次成像Synthesize the multiple imaging data of a scene to one image。把同一地物的多次成像合成为一幅图像Equivalent to “enlarge” the antenna, forming a very long antenna and thus improving the azimuth resolution 等效于增大天线，形成一根很长的天线，从而改善分辨率,Sketch Map（示意图）,(From GlobeSAR program, CCRS),Decomposition of Multiple Imaging（多次成像分解示意图）,舒宁 等 1997,Synthesis of Multiple Imaging（合成）,Objects experience illumination over a time interval Record and save the complete history of reflections （记录和保存了完整回波信号）Permits reconstruction of the reflected signals （反射信号重建）Based on the principle of Doppler frequency shift caused by the relative movement between the antenna and the target（依据多普勒频移原理）By tracing the frequency shifts and thus synthesising the corresponding echoes, the azimuth resolution can be sharpened (SAR focusing technique) （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),For ERS-1/2, a 10m antenna is used to synthesize a nearly 5 km antenna.About 1000 radar images are used to get one SAR image.,Renewed Azimuth Resolution(更新的方位分辨率),Synthetic aperture radar（合成孔径雷达）,Example: ERS-1/-2 SAR Resolution,Antenna length: L=10 m Typical range:,Ground range resolution:,Azimuth resolution:,(Crimea, Ukraine),Real Aperture Radar,Synthetic Aperture Radar,5x14 km pixels,4x20 m pixels,Massonnet and Feigl, 1998,The End,Thank you!,
