针对近地卫星数传时的信道时变性和严重的Ka频段雨衰现象,采用自适应编码调制(Adaptive Coding and Modulation, ACM)技术能够充分利用链路资源,相对于传统的固定编码调制方式,进一步提高链路的数据吞吐量。提出近地卫星Ka频段数传链路...针对近地卫星数传时的信道时变性和严重的Ka频段雨衰现象,采用自适应编码调制(Adaptive Coding and Modulation, ACM)技术能够充分利用链路资源,相对于传统的固定编码调制方式,进一步提高链路的数据吞吐量。提出近地卫星Ka频段数传链路ACM模式设计方法,在降雨环境下建立Ka频段数传链路模型,根据链路预算的信道状况确定ACM选用模式;采用基于导频符号的最大似然信噪比估计算法结合移动平均的平滑方法实现信道估计,有效地减小了估计值的波动。仿真结果表明,无论晴天还是雨天,采用提出的卫星数传链路ACM模式设计方法,能够在保证系统可靠性的同时获取较高的数据吞吐量。展开更多
Multi-frequency same-beam VLBI means that two explorers with a small separation angle are simultaneously observed with the main beam of receiving antennas.In the same-beam VLBI,the differential phase delay between two...Multi-frequency same-beam VLBI means that two explorers with a small separation angle are simultaneously observed with the main beam of receiving antennas.In the same-beam VLBI,the differential phase delay between two explorers and two receiving telescopes can be obtained with a small error of several picoseconds.The differential phase delay,as the observable of the same-beam VLBI,gives the separation angular information of the two explorers in the celestial sphere.The two-dimensional relative position on the plane-of-sky can thus be precisely determined with an error of less than 1 m for a distance of 3.8×105 km far away from the earth,by using the differential phase delay obtained with the four Chinese VLBI stations.The relative position of a lunar rover on the lunar surface can be determined with an error of 10 m by using the differential phase delay data and the range data for the lander when the lunar topography near the rover and the lander can be determined with an error of 10 m.展开更多
文摘针对近地卫星数传时的信道时变性和严重的Ka频段雨衰现象,采用自适应编码调制(Adaptive Coding and Modulation, ACM)技术能够充分利用链路资源,相对于传统的固定编码调制方式,进一步提高链路的数据吞吐量。提出近地卫星Ka频段数传链路ACM模式设计方法,在降雨环境下建立Ka频段数传链路模型,根据链路预算的信道状况确定ACM选用模式;采用基于导频符号的最大似然信噪比估计算法结合移动平均的平滑方法实现信道估计,有效地减小了估计值的波动。仿真结果表明,无论晴天还是雨天,采用提出的卫星数传链路ACM模式设计方法,能够在保证系统可靠性的同时获取较高的数据吞吐量。
基金supported by the‘100 Talents Project’of Chinese Academy of Sciences,China
文摘Multi-frequency same-beam VLBI means that two explorers with a small separation angle are simultaneously observed with the main beam of receiving antennas.In the same-beam VLBI,the differential phase delay between two explorers and two receiving telescopes can be obtained with a small error of several picoseconds.The differential phase delay,as the observable of the same-beam VLBI,gives the separation angular information of the two explorers in the celestial sphere.The two-dimensional relative position on the plane-of-sky can thus be precisely determined with an error of less than 1 m for a distance of 3.8×105 km far away from the earth,by using the differential phase delay obtained with the four Chinese VLBI stations.The relative position of a lunar rover on the lunar surface can be determined with an error of 10 m by using the differential phase delay data and the range data for the lander when the lunar topography near the rover and the lander can be determined with an error of 10 m.
