摘要
月基合成孔径雷达(SAR)与传统低轨SAR相比,成像几何上存在成像距离长的特点,其多普勒参数估计方法也不同于常规的机载和星载SAR.基于喷气推进实验室(JPL)高精度星历,可以通过插值获取月心在地心惯性坐标系下的位置、速度和加速度以及月球天平动,然后经由坐标转换得到月面任意位置在地心惯性坐标系下的位置、速度和加速度.在此基础上,建立了两个二次方程组,第1个方程组的解表示任意星下点离线角和斜视角情况下的波束矢量,第2个方程组求得波束矢量的模值,以此解算地面波束中心的坐标.结果表明,月基SAR的波束角需沿轨不断调整,而且天线放置的位置也会对多普勒参数产生明显影响.
Compared with the low earth orbit synthetic aperture radar（ SAR） system,the moon-borne SAR is distinct from its unique imaging geometry,so the Doppler parameters estimation method is different from conventional pickaback and satellite-borne SAR. Precise jet propulsion laboratory（ JPL） ephemeris was used to interpolate the position,velocity and acceleration of lunar barycenter as well as the libration in geocentric inertial coordinate system. Then the position,velocity and acceleration of an object at any selenographic coordinates were able to be acquired via the coordinate transformation. Based on this,two quadratic equation sets were put forward to calculate the beam direction at any off-nadir angle and squint angle,and to solve the modulus value of line of sight,then coordinating the footprint center. Simulation results show that the beam angle needs a continuous adjustment along the orbit to point the earth disk in moon-borne SAR case,and the antenna position displacement leads to a significant shift on the Doppler parameters.
出处
《北京航空航天大学学报》
EI
CAS
CSCD
北大核心
2015年第1期71-76,共6页
Journal of Beijing University of Aeronautics and Astronautics
基金
国家自然科学基金资助项目(60972141)
国家重点基础研究发展计划资助项目(2009CB723906)
中国科学院战略性先导科技专项课题(XDA04077200)
关键词
月基SAR
多普勒参数
JPL星历
月基对地观测
天平动
moon-borne RAR（synthetic aperture radar）
Doppler parameters
jet propulsion laboratory ephemeris
earth observation from moon
libration
