The impacts of ionospheric scintillation on geosynchronous synthetic aperture radar（GEO SAR）focusing is studied based on the multiple phase screen（MPS）theory.The power spectrum density of electron irregularities i...The impacts of ionospheric scintillation on geosynchronous synthetic aperture radar（GEO SAR）focusing is studied based on the multiple phase screen（MPS）theory.The power spectrum density of electron irregularities is first modified according to the ionospheric anisotropy.Then propagation wave equations in random medium are deduced in the case of oblique incidence in GEO SAR.The amplitude and phase errors induced by the random electron fluctuations are generated by the iterated MPS simulations and are superimposed into the GEO SAR signals.Through the following imaging and evaluation,the effects of the anisotropic ionospheric scintallition on GEO SAR are assessed.At last,the optimized integration time under different ionospheric scintillation conditions are recommended through Monte Carlo experiments.It is concluded that,greater ionospheric fluctuations and longer integration time will result in more severe deterioration,even no focus at all in the worst case.展开更多
In the past few decades, applications of geostationary orbit (GEO) satellites have attracted increasing attention, and with the development of optical technologies, GEO optical satellites have become popular worldwide...In the past few decades, applications of geostationary orbit (GEO) satellites have attracted increasing attention, and with the development of optical technologies, GEO optical satellites have become popular worldwide. This paper proposes a general working pattern for a GEO optical satellite, as well as a target observation mission planning model. After analyzing the requirements of users and satellite control agencies, two objectives are simultaneously considered: maximization of total profit and minimization of satellite attitude maneuver angle. An NSGA-II based multi-objective optimization algorithm is proposed, which contains some heuristic principles in the initialization phase and mutation operator, and is embedded with a traveling salesman problem (TSP) optimization. The validity and performance of the proposed method are verified by extensive numerical simulations that include several types of point target distributions.展开更多
联合甚长基线干涉测量(very long baseline interferometry,VLBI)时延数据与转发式(orbit determination by transfer tracking,ODTT)测距数据能够有效提高地球静止轨道(geostationary earth orbit,GEO)卫星定轨精度。参照位置精度衰减...联合甚长基线干涉测量(very long baseline interferometry,VLBI)时延数据与转发式(orbit determination by transfer tracking,ODTT)测距数据能够有效提高地球静止轨道(geostationary earth orbit,GEO)卫星定轨精度。参照位置精度衰减因子(position dilution of precision,PDOP)的改变,研究不同VLBI基线时延数据与转发式测距数据的联合对GEO卫星定轨精度的改善,可为特定条件下联合观测时VLBI基线的最优选择提供参考。基于中国科学院国家授时中心宽带VLBI系统和转发式测轨系统的实测数据,开展中星12号GEO卫星的定轨试验。试验结果表明定轨精度的提高与PDOP的降低成正相关。相比于转发式单独定轨,联合VLBI系统中的喀什—三亚基线,PDOP降低了3.00,定轨精度提高了11.48%;联合VLBI系统中的吉林—喀什基线,PDOP降低了3.38,定轨精度提高了14.73%;联合VLBI系统中的吉林—三亚基线,PDOP降低了6.90,定轨精度提高了19.75%;联合VLBI系统中的吉林—三亚和吉林—喀什两条基线,PDOP降低了9.94,定轨精度提高了27.23%。展开更多
连线干涉测量(Connected Element Interferometry,CEI)是一种全天时全天候的被动测角技术,已用于空间目标的跟踪监视.地球静止轨道(Geostationary Earth Orbit,GEO)卫星需要频繁机动以保持轨位或完成其他任务,其机动后的快速轨道恢复能...连线干涉测量(Connected Element Interferometry,CEI)是一种全天时全天候的被动测角技术,已用于空间目标的跟踪监视.地球静止轨道(Geostationary Earth Orbit,GEO)卫星需要频繁机动以保持轨位或完成其他任务,其机动后的快速轨道恢复能力对于监视预警极为重要.针对基于CEI的GEO短弧定轨和预报,分析了定轨算法的形亏和数亏,在附加先验轨道约束的短弧定轨基础上,提出了轨道半长轴初值的自适应优化方法.利用亚太七号卫星的CEI仿真和实测数据进行了短弧定轨和预报,实验结果表明,采用优化后的半长轴初值,30min短弧定轨和10min预报的卫星位置分量精度均优于4km,能够满足非合作GEO目标机动后快速轨道恢复的需求.展开更多
基金Supported by the National Natural Science Foundation of China(61225005,61427802,61471038,61120106004)Chang Jiang Scholars Program(T2012122)+1 种基金111 project of China(B14010)Beijing Higher Education Young Elite Teacher Project(YETP1168)
文摘The impacts of ionospheric scintillation on geosynchronous synthetic aperture radar（GEO SAR）focusing is studied based on the multiple phase screen（MPS）theory.The power spectrum density of electron irregularities is first modified according to the ionospheric anisotropy.Then propagation wave equations in random medium are deduced in the case of oblique incidence in GEO SAR.The amplitude and phase errors induced by the random electron fluctuations are generated by the iterated MPS simulations and are superimposed into the GEO SAR signals.Through the following imaging and evaluation,the effects of the anisotropic ionospheric scintallition on GEO SAR are assessed.At last,the optimized integration time under different ionospheric scintillation conditions are recommended through Monte Carlo experiments.It is concluded that,greater ionospheric fluctuations and longer integration time will result in more severe deterioration,even no focus at all in the worst case.
基金supported by the National Natural Science Foundation of China(7150118061473301)
文摘In the past few decades, applications of geostationary orbit (GEO) satellites have attracted increasing attention, and with the development of optical technologies, GEO optical satellites have become popular worldwide. This paper proposes a general working pattern for a GEO optical satellite, as well as a target observation mission planning model. After analyzing the requirements of users and satellite control agencies, two objectives are simultaneously considered: maximization of total profit and minimization of satellite attitude maneuver angle. An NSGA-II based multi-objective optimization algorithm is proposed, which contains some heuristic principles in the initialization phase and mutation operator, and is embedded with a traveling salesman problem (TSP) optimization. The validity and performance of the proposed method are verified by extensive numerical simulations that include several types of point target distributions.
文摘联合甚长基线干涉测量(very long baseline interferometry,VLBI)时延数据与转发式(orbit determination by transfer tracking,ODTT)测距数据能够有效提高地球静止轨道(geostationary earth orbit,GEO)卫星定轨精度。参照位置精度衰减因子(position dilution of precision,PDOP)的改变,研究不同VLBI基线时延数据与转发式测距数据的联合对GEO卫星定轨精度的改善,可为特定条件下联合观测时VLBI基线的最优选择提供参考。基于中国科学院国家授时中心宽带VLBI系统和转发式测轨系统的实测数据,开展中星12号GEO卫星的定轨试验。试验结果表明定轨精度的提高与PDOP的降低成正相关。相比于转发式单独定轨,联合VLBI系统中的喀什—三亚基线,PDOP降低了3.00,定轨精度提高了11.48%;联合VLBI系统中的吉林—喀什基线,PDOP降低了3.38,定轨精度提高了14.73%;联合VLBI系统中的吉林—三亚基线,PDOP降低了6.90,定轨精度提高了19.75%;联合VLBI系统中的吉林—三亚和吉林—喀什两条基线,PDOP降低了9.94,定轨精度提高了27.23%。
文摘连线干涉测量(Connected Element Interferometry,CEI)是一种全天时全天候的被动测角技术,已用于空间目标的跟踪监视.地球静止轨道(Geostationary Earth Orbit,GEO)卫星需要频繁机动以保持轨位或完成其他任务,其机动后的快速轨道恢复能力对于监视预警极为重要.针对基于CEI的GEO短弧定轨和预报,分析了定轨算法的形亏和数亏,在附加先验轨道约束的短弧定轨基础上,提出了轨道半长轴初值的自适应优化方法.利用亚太七号卫星的CEI仿真和实测数据进行了短弧定轨和预报,实验结果表明,采用优化后的半长轴初值,30min短弧定轨和10min预报的卫星位置分量精度均优于4km,能够满足非合作GEO目标机动后快速轨道恢复的需求.
