一种瞬时大带宽DRFM系统的信道化设计

为实现宽带雷达回波信号的模拟生成,通常采用基于信道化技术的射频存储(DRFM)系统。在信道化DRFM系统中,不合理的信道划分方案和多相滤波器设计会导致频谱混叠、频谱分量缺失和幅度失真。文章提出了一种相邻信道频谱有50%交叠的信道划分方法,并对信道化滤波器组进行了优化设计。在此基础上,给出了一种瞬时大带宽DRFM系统的实现方案。仿真结果表明,文章提出的设计方案可以实现Nyquist采样带宽内雷达信号的射频存储和模拟转发,且具有较小的幅度失真,可以满足瞬时大带宽雷达回波信号的模拟需求。     

Real-time ray-based channel generation and emulation for UAV communications

A real-time ray-based hardware emulator for Unmanned Aerial Vehicle (UAV) communication channels which suits for the Three-Dimensional (3D) dynamic scenarios and considers the movements of both terminals is developed in this paper. The time-variant channel parameters, i.e., ray delay, ray gain, and ray Doppler frequency are precalculated in the host by using the Ray Tracing (RT) method. Meanwhile, RT simulation dramatically increases the number of valid rays. To address the problem of resource limitation and huge computational burden in the implementation, an efficient ray coefficients generation method based on iteration is proposed and implemented. With the advantages of low cost and high flexibility, a Software Defined Radio (SDR) hardware platform is used to emulate the ray-based UAV channels by utilizing the compact architecture including the Time-Division (TD) scheme and Tapped-Delay Line (TDL) for channel convolution. Finally, hardware measurement results demonstrate that the properties of emulated channel, i.e., Power Delay Profile (PDP) and Doppler Power Spectrum Density (DPSD) consist with the simulated ones, which verifies the correctness of hardware implementation. The proposed channel emulator provides an efficient way for optimization, verification, and evaluation of UAV communication systems.     

合成孔径雷达射频干扰抑制技术进展及展望

射频干扰(RFI)是影响合成孔径雷达精确遥感的一个难点问题,严重阻碍了原始回波的采集、成像和后续解译过程。本文对适用于合成孔径雷达系统的RFI抑制技术进行了综述研究。首先分析了典型的星载和地面RFI源以及其对合成孔径雷达系统的影响,给出了典型RFI类型的信号模型和实测数据示例;然后系统地介绍了抑制RFI的先进信号处理技术,并从适用性的角度讨论了每种方法的优缺点;最后从认知、综合和自适应的角度探讨了未来干扰抑制技术的发展趋势与展望。     

基于卫星轨道软件平台的自主导航计算方法

为增强卫星的自主生存能力，研究了基于卫星轨道软件平台的自主导航计算方法。由星载导航部件获取导航参数，应用数值或解析法进行自主导航计算，以实时获得精确的轨道参数。理论分析和仿真结果表明，读方法正确可行，具有较高的工程应用价值。     

6G service-oriented space-air-ground integrated network: A survey

As an indispensable component of the emerging 6G networks, Space-Air-Ground Integrated Networks (SAGINs) are envisioned to provide ubiquitous network connectivity and services by integrating satellite networks, aerial networks, and terrestrial networks. In 6G SAGINs, a wide variety of network services with the features of diverse requirements, complex mobility, and multi-dimensional resources will pose great challenges to service provisioning, which urges the development of service-oriented SAGINs. In this paper, we conduct a comprehensive review of 6G SAGINs from a new perspective of service-oriented network. First, we present the requirements of service-oriented networks, and then propose a service-oriented SAGINs management architecture. Two categories of critical technologies are presented and discussed, i.e., heterogeneous resource orchestration technologies and the cloud-edge synergy technologies, which facilitate the interoperability of different network segments and cooperatively orchestrate heterogeneous resources across different domains, according to the service features and requirements. In addition, the potential future research directions are also presented and discussed.     

空间低频射电天文天线材质-观测性能分析

15MHz以下的射电天文信号由于受到电离层的阻挡只能通过空间卫星平台进行观测。采用空间展开的电小天线是目前普遍的做法。就电小天线的材质-接收性能方面进行分析，构建了基于材质磁导率、电导率对后端接收机噪声影响模型。通过计算结果比对和就天线材质空间展开难易程度的综合考虑，归纳总结了不同材质对空间低频射电天文观测噪声影响以及展开难度，为新天线的研制提供了数据依据。该项工作将为下一步L1点空间天气监测卫星中的太阳射电观测载荷提供技术支持。     

基于1553B总线的星载嵌入式软件在轨升级方法

针对星载嵌入式软件在轨升级难的问题,提出了基于1553B总线的星载嵌入式软件在轨(线)升级方法。通过1553B总线接收升级程序、固化程序和升级程序分区独立存储、启动程序和应用程序互相配合的方式,实现软件升级、部分传输异常时补丁升级及升级异常情况下的版本回退。在某星载固态存储设备上对方法进行了试验验证,结果表明,方法可对星载固态存储设备的软件进行在轨(线)升级,升级程序异常情况下可通过设备开关电自动回退版本,部分出错时上注补丁量少,提高了星载嵌入式软件测试维护和在轨维护的效率和可靠性。