中继卫星SMA系统前向链路多波束形成技术

提出了一种新的中继卫星前向SMA(S频段多址)系统前向链路中多波束形成方法,即在地面采用数字移相代替中继星星上模拟移相完成波束形成;指出了需要解决的关键技术问题和解决方法,通过"星(用户星)-星(中继星)-地"无线联试,验证了地面数字移相的正确性,对简化中继星上设备、实现前向链路同时多目标能力具有积极意义.     

星间激光链路数据中继技术研究进展

基于高性能激光链路构建高速安全的数据中继卫星系统可为不同轨道、不同功能的对地观测卫星和用户航天器提供大容量、无缝隙的数据中继服务,在军事和民用领域均具有广泛的应用前景。以欧洲为代表的发达国家相继开展了星间激光链路数据中继技术的理论研究和星上演示验证,并启动了相应的工程验证计划。综述了国内外星间激光链路数据中继技术的研究现状,对几种典型激光链路数据中继卫星系统,着重研究了系统结构、激光终端及模拟验证实验。最后,分析了数据中继卫星激光链路组网中着重关注的几个方向。     

激光链路中继卫星系统网络设计及性能分析

随着卫星激光通信技术的发展,激光链路中继卫星系统将成为未来天基信息系统的骨干网。首先设计了一种2颗国土星+2颗境外星的网络架构,然后借助地面程控交换技术分析方法,定义了光网络性能指标,最后仿真了激光链路中继卫星系统的网络性能。仿真结果表明,当每颗用户卫星通信业务量为0.2 Erl、接入损失概率要求不大于0.2、链路利用率不小于0.6的情况下,激光链路中继卫星系统的12条接入链路可以支持50颗用户卫星接入。     

国外激光链路中继卫星系统的发展与启示

激光链路中继卫星系统是指以激光波束为媒介,为低轨信息获取类卫星提供高速数据传输服务的卫星系统。国外已开展了多次星间、星地激光通信实验,已由强度调制/直接探测通信体制过渡到相位调制/相干解调通信体制,通信速率可达5.6 Gbps。卫星激光通信正向更高通信速率、组网应用、终端小型化、轻量化方向发展。在系统分析欧洲、日本、美国等国家典型星间、星地激光通信实验和中继卫星发展计划的基础上,讨论了激光链路中继卫星系统的发展趋势,总结得到对发展我国激光链路中继卫星系统的若干启示。     

中继卫星资源调度问题研究现状与展望

随着跟踪与数据中继卫星系统(TDRSS)的发展以及中继应用需求的增加,其资源调度成为决定系统性能的关键因素之一.分析了包括描述方法、活动与资源、约束条件等在内的中继卫星资源调度问题基本内涵,研究了目前中继卫星资源调度的数学模型和实现算法,比较了不同数学模型和实现算法的优缺点.针对未来卫星激光和微波链路联合组网的发展趋势,提出了基于多终端-多节点及基于资源故障的激光/微波混合链路中继卫星资源调度的基本方法.     

跟踪和数据中继卫星系统的微波光调制技术研究

为了提高跟踪和数据中继卫星系统的传输容量,采用ITU推荐的Ka波段为星间微波链路的通信波段,跟踪和数据中继卫星之间采用激光链路.设计采用了激光链路透明传输微波信号的调制技术,包括直接微波信号调制和微波信号变频调制两种方案.通过分析和计算,得到了Ka波段微波光调制器的主要技术参数,论证了宽带LiNbO3行波调制器用于该系统的可行性,并讨论了两种方案的优缺点.     

功率约束下的星地协作网络中断概率分析

针对星地协作网络,考虑中继节点转发卫星节点信号时会受发射功率和干扰功率约束,提出了一种基于中继节点与目的节点间链路最大信噪比准则来选择中继节点的放大转发部分中继选择策略。在卫星链路遭受阴影莱斯衰落和地面链路遭受瑞利衰落情况下,推导出系统中断概率下界的闭合表达式。仿真结果表明了理论分析的正确性,并展示了不同阴影莱斯信道参数、不同中继数目、不同功率约束对中断概率的影响。     

无人机无线电综合测控系统

<正> 无人机无线电综合测控系统是无人机系统的重要组成部分,采用地空视距链路,空中中继链路或卫星中继链路,分别实现对近程、短程、中程、远程无人机的遥控、遥测、跟踪定位和视频信息传输。系统由地面主测控站、机动测控站、视频接收站和机载设备等组成。     

AF双向中继网络中一种新的中继选择算法

通过高信噪比条件下AF双向中继网络总速率的近似表达,给出了链路增益乘积和系统总速率之间的关系式。基于此关系式提出一种最大化链路增益乘积中继选择算法(Maximum Relay Selection,MRS),在中继处引入门限,将链路质量超过门限的中继选出建立可靠候选集。在建立的可靠候选集中以两跳链路增益乘积最大化为标准,实现最佳中继选择。通过仿真将该中继选择算法与现有AF双向中继网络3种不同中继选择算法进行性能比较。仿真结果表明,该中继选择算法能在同时保证AF双向中继网络两跳链路质量的前提下,提高系统的总速率。     

基于中继卫星的载人航天天基测控体系研究

基于中继卫星的天基测控系统在我国载人航天测控系统中扮演越来越重要的角色,本文从天基测控体系的优势入手,介绍了基于中继卫星的天基测控体系工作原理,并对天基测控终端的组成及关键技术进行了研究,给出了天基测控终端的组成原理框图及与中继卫星一天内可建立通信链路的情况。     

A MEO Tracking and Data Relay Satellite System Constellation Scheme for China

A medium earth orbit （MEO） tracking and data relay satellite system （TDRSS） constellation scheme for China is proposed. This system consists of MEO satellite constellation, inter-satellite links （ISLs） and terrestrial gateway station, which can provide continuous bidirectional data transmission links between low altitude spacecrafls and the terrestrial gateway station in China. Theoretical analysis and simulation results indicate that the proposed constellation can cover the global low altitude space sphere and earth surface of China continuously, and has a preferable practical perspective.     

基于改进小生境遗传算法的微波/光混合链路中继卫星资源调度方法

针对微波/光混合链路中继卫星系统多资源约束 下的多目标综合调度问题,分析了微波与激光混 合链路的主要特点和影响因素,建立了混合链路资源调度多目标约束规划模型;将小生境技 术引入遗传 算法,并设计了基于精英保留的选择机制和自适应的交叉、变异算子,提出了一种改进的小 生境遗传算 法对模型进行求解。所提算法可有效避免遗传算法局部优化能力差及容易陷入局部最优等缺 陷,同时能够 防止最优解的丢失,解决了混合链路多资源约束下的多目标综合调度问题。仿真结果表明 ,相对与传统 的遗传算法,本文算法在保持种群多样性和求解全局最优解方面具有优势,有效解决微波/ 激光混合链路中继卫星系统的多目标综合调度问题。     

Pointing, acquisition and tracking for optical space communications

Free-space links between satellites provide a means of introducing increased connectivity into a satellite system. This can result in enhanced traffic capacity and extended coverage for telecommunication systems and real-time relay of instrument data to the ground for Earth observation missions. Optical links offer the potential advantages over microwave links of lower mass and power and reduced size so that they can be accommodated more easily on the satellite. However the narrow optical beamwidths involved result in stringent pointing, acquisition and tracking (PAT) requirements. This paper describes a concept for a compact PAT system which employs a passive antivibration mount to filter out high-frequency disturbances from the satellite. This is under development as part of the ESA-funded Small Optical User Terminal (SOUT) programme. The system concept, hardware implementation, and results of breadboarding critical items are presented     

基于浮空平台的星地激光中继通信系统设计

针对星地激光通信受大气环境影响较大,无法全天候工作的难题,可考虑在18~22 km的平流层高度部署星地激光中继通信系统。其中卫星与平流层中继系统间采用激光通信,平流层中继系统与地面间采用大容量毫米波通信,基本消除大气环境(云、雨、雾、大气湍流等)对激光通信的影响,提高星地激光馈电链路可用度。受限于平流层平台成熟度不足,需首先开展基于成熟浮空平台的星地激光中继通信系统研究,先期对缓慢移动浮空平台搭载激光通信载荷与卫星间链路对准,激光通信载荷在浮空平台顶部柔性表面安装可行性等关键技术进行验证,为后续在平流层高度部署临近空间信息网络提供技术支撑。     

CO2laser communication systems for near-earth space applications

Projects of the growth of earth-sensing systems for the latter half of the 1980's show a data transmission requirement of 300 Mbit/s and above. Mission constraints and objectives lead to the conclusion that the most efficient technique to return the data from a sensing satellite to a ground station is through a geosynchronous data relay satellite. Of the two links that are involved (sensing satellite to relay satellite and relay satellite to ground), a laser system is most attractive for the space-to-space link. A five-year program was conducted which has shown the basic technical feasibility of accomplishing this link with a CO2laser system operating at a wavelength near 10 µm. The system uses a mercury-cadmium-telluride infrared mixer cooled to approximately 100 K by a radiative cooler. The laser local oscillator and coupling-modulated laser transmitter use conductively cooled beryllium oxide construction. The optical antenna used for transmission and reception has a gain of nominally 92 dB with a 3-dB beamwidth of 80 µr. Tracking jitter is less than ten µr and signal acquisition occurs in less than 1 min. The receiver subsystem has a sensitivity of 10^-19W/Hz, accommodates a 300-Mbit/s data rate, and can track Doppler frequency variations over a ±700-MHz range.     

A flexible LEO satellite modem with Ka‐band RF frontend for a data relay satellite system

From a geostationary Earth orbit (GEO) satellite's perspective, a low Earth orbit (LEO) satellite is visible on more than half of its orbit. Albeit the free‐space loss of an inter‐satellite link is much higher than the one of a direct ground link, considerable data rates and download volumes can be achieved. In this paper, we describe the system architecture of an integrated approach for a data relay satellite system and the development of LEO satellite and ground station modems. The approach allows serving several small and inexpensive LEO satellites at the same time both with low rate telemetry/telecommand links and with high rate download of sensor data.     

基于STK/Schedule实现中继卫星业务调度

中继卫星调度问题是中继卫星系统应用中的关键问题之一。STK/Schedule模块不仅提供了优秀的时序和任务规划算法,还对外提供了应用程序接口。通过分析中继卫星系统资源、可见性以及任务约束特点,提出了利用STK/X组件调用STK/Schedule的可视化计算以及调度算法进行二次开发的方法。在简化应用程序开发难度的同时,解决了多用户多任务需求的情况下的中继卫星业务调度问题。     

An adaptive calibration and beamforming technique for a GEO satellite data relay

High throughput data links from low Earth orbit satellites through a geostationary orbit satellite data relay have been proposed to increase the available contact times to ground stations. Accurate antenna beam pointing and tracking of moving targets are key requirements for the relay satellite. In this work, we propose an adaptive calibration and beamforming methodology on the basis of least mean squares, which is suitable for a geostationary orbit data relay. The target system consists of the combination of a high gain reflector fed by a digitally steerable patch antenna array. The proposed method is first presented by numerical cosimulation of the antenna and the calibration algorithm. The results are then validated in an outdoor experimental setup with all digital signal processing implemented in a field‐programmable gate array. We demonstrate the tracking ability and pointing performance of the digitally enhanced reflector antenna with gain fluctuations smaller than 3 dB over a field of view of at least 2,5°. The demonstrated performance shows that the digitally enhanced reflector antenna is a suitable candidate for long‐distance space communications.     

基于TDRSS阵列天线的目标跟踪算法

采用基于跟踪与数据中继卫星系统构建的天地一体化遥测、跟踪与指挥系统,不仅能有效地提高遥测、跟踪与指挥的覆盖率、定轨精度、飞行器全程测量和对多目标的同时遥测、跟踪与指挥能力,而且能够完成各类对地观测卫星的高速实时数据回传的任务。与常规的测控系统不同的是,中继星的遥测、跟踪与指挥是在地球这一复杂的背景环境下进行的,因而会受到各种各样的干扰。采用阵列天线对目标进行自适应跟踪可以实现空域滤波,使信号得到加强,干扰得到抑制。采用Matlab软件仿真了中继星对目标星的跟踪过程,并对两种经典的自适应跟踪算法（LMS,DMI）进行了研究。通过分析信号干扰比的变化,比较两种算法的跟踪性能。