无人机在干扰卫星通信系统中的应用

随着军事信息化程度越来越高,军事卫星通信已成为军事通信和战场通信的重要组成部分。卫星通信干扰和抗干扰技术已受到各国的重视。文章首先分析了干扰卫星通信系统的几种途径,然后分析了无人机在干扰卫星通信系统中的应用及优势。     

Strategies for in-orbit calibration of drag-free control systems

Drag-Free Satellites (DFS) are a class of scientific satellite missions designed for research on fundamental physics as well as geodesy. They consist, basically, of a small inner satellite (test mass) located in a cavity inside a larger satellite, the normal one. The Drag-Free Attitude Control System (DFACS) is the most complex technology on-board these satellites. This key technology allows the residual accelerations on experiments on board the satellites to be significantly reduced. In order to achieve this very low disturbance environment (for some missions <10⁻¹⁴ g) the drag-free control system has to be optimized. This optimization process is required because of uncertainties in system parameters that demand a robustness of the control system. This paper will present approaches for in-orbit calibration of drag-free control systems. The discussion includes modeling, with scale factors and cross couplings, possible excitation signals, comparison of different parameter identification/estimation methods as well as simulation results.     

基于移动式网络的LEO卫星星座通信网络研究

为飞机等交通工具内的用户提供基于卫星的不间断IP连接，并在卫星星座网络内实现IP路由选择功能，是未来LEO卫星星座通信网络需要解决的关键问题。提出了基于移动式网络技术的LEO卫星星座通信网络体系结构，实现了卫星星座通信网络中的IP路由选择功能，并降低了对地面网路的依赖，实现了对用户段网络随时随地的连接支持。在对卫星星座通信网络中的星地切换模式进行分析的基础上，提出了一种基于虚拟移动路由器的快速星地切换和认证方法。通过NS2仿真试验，给出了新型LEO卫星星座通信网络的传输延迟特性以及快速切换方法的仿真试验结果。仿真试验表明，提出的网络结构是满足未来卫星星座发展需求的，星地间的切换是低时延的。     

基于OMNeT++的卫星姿态控制系统仿真

针对三轴稳定卫星的姿态控制系统,在离散事件仿真平台OMNeT 的基础上,建立了一个以星敏感器和陀螺为敏感器,反作用飞轮为执行机构的闭环控制仿真系统。采用双矢量定姿算法和PID控制算法,对该卫星在对地定向模式下的控制精度进行了仿真。仿真结果清晰地反映了星敏感器和反作用飞轮输出延时对控制精度的影响。整个仿真系统符合面向对象和模块化的程序设计理念,并实现了仿真程序的重用。     

气浮台在卫星控制系统仿真中的应用

本文叙述单轴和三轴气浮台仿真设备在卫星控制系统仿真中的应用,主要包括空间太阳望远镜高精度姿控系统单轴气浮台物理仿真试验研究、大型卫星平台单框架控制力矩陀螺(CGCMG)控制系统三轴气浮台物理仿真试验研究、东方红四号卫星控制系统全物理仿真试验.     

卫星热控电压测量模块研制

卫星热控电压测量是保障卫星可靠性、安全性的重要环节。由于测量的特殊性,要求研制与整星热控系统相适合的电压测试模块。采用信号隔离、输入保护等措施保证测量的安全性;采用较高分辨力数据采集及量化技术、以及自校准技术保证测量的可靠性。通过微处理器控制测量过程,LAN接口实现计算机数据传输和通信控制,提高了测量效率。     

Recent advances in observing mesoscale ocean dynamics with satellite altimetry

The paper provides a review of recent results on mesoscale ocean dynamics derived from satellite altimetry. Since 1992, we have had an unprecedented 18 year high-resolution monitoring of the ocean mesoscale field. Altimetry is often used in mesoscale studies in synergy with other remote sensing techniques and in situ data. This global, high-resolution data set has allowed oceanographers to quantify the previously unknown seasonal and interannual variations in eddy kinetic energy and eddy heat and salt transports, and investigate their causes. Eddy tracking techniques have allowed us to monitor their propagation pathways, to bring to light the meridional divergence of cyclones and anticyclones, and to question the role of Rossby waves versus non-linear eddies in the mid to high latitude bands. Altimetry has also revealed the presence of zonal fronts and jets everywhere in the ocean, and brought to light how mesoscale eddies can impact back onto the atmospheric circulation. Finally, altimetry, in synergy with other observations and high-resolution numerical models, has helped reveal the complexity of the sub-mesoscale features, associated with stirring and mixing around the mesoscale eddies, of great importance for the vertical exchange of oceanic tracers. Altimetry has revealed the complexity of the mesoscale system… the scientific community is now working to understand the interplay between these mesoscale eddies, the ocean interior and its impact on the overlying atmosphere.     

卫星双向时间频率传递校准技术综述

卫星双向时间频率传递技术是高精度时间频率远程比对的基本手段,其时间比对A类标准不确定度优于0.1ns,B类标准不确定度主要取决于系统的校准。本文简述了卫星双向时间频率传递的基本理论,着重说明各种卫星双向时间频率传递系统校准方法和硬件实现,对各种校准技术进行评述和比较,总结并展望了校准技术发展的方向。     

卫星测控天线日照温度场极端工况预测方法

针对卫星测控天线日照温度场产生的热变形影响天线电性能问题,提出了一种预测天线极端温度工况的方法.该方法将太阳照射参数与天线面板方程有效结合起来,求得天线面板的太阳直射点运动轨迹,从而确定天线姿态参数.在Ⅰ-DEAS中建立该姿态的模型,同时引入环境因素的影响,进行瞬态仿真分析,预测天线的极端温度工况.通过试验天线,验证理论计算太阳直射点运动轨迹与极端温度预测方法的正确性.     

一种高动态环境下卫星扩频信号的快速捕获方法研究

现代卫星导航及测控应用对接收机在高动态环境下实现测量通信提出了迫切需求。为了解决大多普勒频偏扩频信号的快速捕获问题,提出了一种在频域并行搜索码相位及多普勒频偏的双频域快速捕获方法。采用双块补零算法将长的相关积分操作分割为多个短的相关积分操作,然后采用快速傅里叶变换进行圆周相关,大大节约了处理时间,利用频域圆周移位与时域载波剥离等价的原理,大幅提高了频率搜索效率。与时域相关算法和单频域计算方法相比,在捕获灵敏度不变的条件下,该方法将计算量减少90%,显著提高了运算速度,适合高动态环境下扩频信号的快速捕获。该方案应用于星载接收机平台FPGA实现,测试结果表明该方案可以在0.1s内完成±500kHz频偏下扩频信号捕获。