利用卡尔曼滤波快速确定GPS整周模糊度的研究

给出一种快速确定 GPS整周模糊度的方法 ,该算法根据载体运动特性 ,构造了卡尔曼 (Kalman)滤波器的状态方程 ,通过去相关处理 ,消除或减弱短时间内 GPS载波双差观测量的相关性 ,这不仅改善了 Kalman滤波器的稳定性 ,而且提高了确定 GPS整周模糊的可靠性 ,仿真结果表明 :对于短基线的情况 ,在较短的时间内 ,经过去相关处理有利于正确确定 GPS整周模糊度     

载人航天器的再入与回收

文中主要概述了美国载人飞船回收技术的发展,介绍了保证载人飞船安全返回着陆的方法、采用的回收控制技术、地面对再入返回段的测控支持、载人飞船的回收作业、载人飞船的应急返回和回收救援等技术问题。     

高速DQPSK解调器的算法及实现

介绍了一种高速四相差分相移键控(DQPSK)解调器的算法。该方法基于锁相环原理，并采用了现场可编程逻辑门阵列(FPGA)芯片进行载波恢复、差分解码、时钟恢复和判锁等，其设计与实现不仅方便，而且可靠性高。     

航天器再入与着陆降落伞系统分析

文章主要对航天器再入与着陆落伞系统作了综述,并介绍了各种航天器回收降落伞系统的特点。     

DVB-S接收机中时钟与载波同步的FPGA实现

介绍数字滤波平方定时算法和硬判决型科斯塔斯环的基本原理,并基于这两种算法,用可编程器件FPGA实现DVB-S接收机中的采样时钟同步和载波同步。整个设计基于XILINX公司的ISE平台,用VHDL编程语言通过逻辑综合和仿真在xc3s2000 FPGA芯片上实现。     

载人航天器着陆场选择探讨

文中介绍美国和俄罗斯载人航天器的着陆场位置,简述了着陆场任务和选择飞船式载人航天器着陆场时应考虑的几个问题及相应要求。     

600Mb/s高速数传接收机的设计与实现

提出一种基于FPGA的600Mb/s高速数传接收机全数字实现方案,对采用Costas环的载波恢复算法和采用并行数据转换跟踪环的码同步算法作了介绍。测试结果表明,该接收机在码速率小于350Mb/s时,解调损失小于1.5dB;在码速率为600Mb/s时,解调损失小于3dB。     

物—伞系统运动稳定性初探

弹道－升力式再入飞行器常采用旋成体外形，但其质心偏离对称轴（纵轴）设置。这种飞行器在着陆前要采用降落伞作为主减速手段。研究质心偏离对称轴的旋成体与降落伞组成的系统的运动稳定性是一项有工程实践意义的课题。作为一种初步探索，在把降落伞视作刚体的条件下，按该系统平面运动方程考察其在平衡状态附近的稳定性，给出了运动稳定性判据。     

Seasonal variations of GPS derived TEC at three different latitudes of the southern hemisphere during geomagnetic storms

Data from the archive of the International GNSS Services (IGS) were used to study the seasonal variations of Total Electron Content (TEC) over three stations located at different latitudes in the southern hemisphere during the geomagnetic storms of 11 January, 6 April, 8 June, and 13 October 2000, representing storms that occurred in summer, autumn equinox, winter and spring equinox, respectively. The percentage TEC deviation with respect to reference values differs substantially from season to season. A strong seasonal anomaly and clear equinoctial asymmetry in TEC response to the storms were observed. Weak and short-lived positive TEC deviations as well as strong and long-lasting negative trends were observed in summer storm during the main and recovery phases respectively over the high and low latitudes whereas in winter storm, the highest positive TEC deviations was recorded during the main phase over the entire latitudes. TEC enhancement dominated all the stations during the autumn (March) equinox storm while TEC depletion was majorly observed during the spring (September) equinox. All these variations find their explanations in the thermospheric composition change and circulation. Future work with direct or modeled measurement of atomic Oxygen to molecular Nitrogen ratio (O/N₂), large number of storms and other possible factors such as variations in storm’s intensity and local time dependence of the storm onset is expected to validate the observations in this study.     

无人船数据链SC-FDE突发信号载波同步方法

设计了一种适用于无人船组网数据链的SC-FDE突发通信时隙的帧结构,通过计算前导序列和独特字(UW)序列的自相关函数,调整差分相关长度,提出一种适用于多模式帧结构的载波同步方法。最后,通过仿真评估了所提出算法在不同条件下的有效频偏估计范围、频偏估计精度等性能,为算法工程实现的主要设计参数提供参考。