国外中继卫星对航天器交会对接的测控通信支持

中继卫星系统的天基测控通信是近代航天技术的重大突破,它能够有效地满足航天器交会对接的测控通信需要。文章分析了美国＂跟踪与数据中继卫星系统＂（TDRSS）和欧洲＂阿特米斯＂（ARTEMIS）中继卫星对＂自动转移飞行器＂（ATV）与＂国际空间站＂（ISS）交会对接任务的测控通信支持,总结了国外中继卫星系统支持航天器交会对接...     

地球同步卫星轨道漂移对天线指向的影响分析

位于地球同步轨道的卫星由于受各种空间因素的影响，其运行轨道会随时间逐渐偏离地球赤道面．轨道倾角由0°逐渐增大。这种轨道倾角漂移会导致对地通信的固定波束天线指向偏离地面站，引起天线指向失配误差，造成通信质量下降甚至丧失。文章分析了轨道漂移对天线指向的影响，并给出了天线指向调整的策略。     

Results of Kirari optical communication demonstration experiments with NICT optical ground station (KODEN) aiming for future classical and quantum communications in space

Bi-directional ground-to-satellite laser communication experiments were successfully performed between the optical ground station developed by the National Institute of Information and Communications Technology (NICT), located in Koganei City in suburban Tokyo, and a low earth orbit (LEO) satellite, the “Kirari” Optical Inter-orbit Communications Engineering Test Satellite (OICETS). The experiments were conducted in cooperation with the Japan Aerospace Exploration Agency (JAXA), and called the Kirari Optical communication Demonstration Experiments with the NICT optical ground station (or KODEN). The ground-to-OICETS laser communication experiment was the first in-orbit demonstration involving the LEO satellite. The laser communication experiment was conducted since March 2006. The polarization characteristics of an artificial laser source in space, such as Stokes parameters, and the degree of polarization were measured through space-to-ground atmospheric transmission paths, which results contribute to the link estimation for quantum key distribution via space and provide the potential for enhancements in quantum cryptography on a global scale in the future. The Phase-5 experiment, international laser communications experiments were also successfully conducted with four optical ground stations located in the United States, Spain, Germany, and Japan from April 2009 to September 2009. The purpose of the Phase-5 experiment was to establish OICETS-to-ground laser communication links from the different optical ground stations and the statistical analyses such as the normalized power, scintillation index, probability density function, auto-covariance function, and power spectral density were performed. Thus the applicability of the satellite laser communications was demonstrated, aiming not only for geostationary earth orbit-LEO links but also for ground-to-LEO optical links. This paper presents the results of the KODEN experiments and mainly introduces the common analyses among the different optical ground stations.     

Feasibility assessment of optical technologies for reliable high capacity feeder links

Space telecom scenarios like data relay satellite and broadband/broadcast service providers require reliable feeder links with high bandwidth/data rate for the communication between ground station and satellite. Free space optical communication (FSOC) is an attractive alternative to microwave links, improving performance by offering abundant bandwidth at small apertures of the optical terminals. At the same time Near-Earth communication by FSOC avoids interference with other services and is free of regulatory issues. The drawback however is the impairment by the laser propagation through the atmosphere at optical wavelengths. Also to be considered are questions of eye safety for ground personnel and aviation. In this paper we assess the user requirements for typical space telecom scenarios and compare these requirements with solutions using optical data links through the atmosphere. We suggest a site diversity scheme with a number of ground stations and a switching scheme using two optical terminals on-board the satellite. Considering the technology trade-offs between four different optical wavelengths we recommend the future use of 1.5 µm laser technology and calculate a link budget for an atmospheric condition of light haze on the optical path. By comparing link budgets we show an outlook to the future potential use of 10 µm laser technology.     

Feasibility of using statellites in non-equatorial 24-hour circular orbits for communications

The early sixties witnessed the debate among competing candidate orbits that led to the emergence of perfect geostationary systems as virtually the sole “instruments” for satellite communication. The subsequent problem of overcrowding of geostationary ring on one hand and explosive growth in demand on communication capacity on the other led comsat experts to focus on the alternate routes through various near-earth and medium attitude satellite constellations later proposed for uninterrupted communication. However, the opportunities thrown up by quasi-stationary orbits for augmentation of the space communication capacity have gone abegging. This paper attempts to draw attention of communication satellite designers/planners to the immense potential for utilization of the non-equatorial, 24-hour circular orbits for communication. For the proposed quasi-stationary orbits, the change and/or control of the inclination of the plane is not envisaged in the launch and/or operational phase. The resulting significant payload weight advantage is associated with the problem of periodic as well as secular apparent angular satellite drift relative to the ground terminal. However, the problem may be largely overcome through controlled satellite tilting using solar radiation pressure or through the use of tethered auxiliary mass attachment. Alternatively, it may be possible to overcome the attitude control problem by the use of systems such as on-bard electronically steerable phased array antenna capable of following the line-of-sight to the co-operative ground station.     

Q/V频段电磁波在等离子体鞘套下的传输特性

高超声速飞行器再入地面时，由于飞行器表面等离子体电子密度分布不均匀，因此从背风面向天基中继卫星传输，可避开迎风面的高电子密度，并以Q/V频段为测控频段，经中继卫星转发至地面测控站。本文以波阻抗方法为基础，分析了Q/V频段在不同等离子体参数下的传输特性，并仿真了等离子体对Q/V频段天线波束指向的影响。结果表明：Q/V频段在等离子体中穿透性更好，可在更高的等离子体电子密度和碰撞频率下保持较低的衰减值。但Q/V频段下的天线波束指向偏差较大，随着频段的提高和入射角度的减小，偏差值逐渐减小。因此，应用Q/V频段，通过中继卫星转发实现实时通信，有利于缓解再入飞行器“黑障”现象。     

搭建地月鹊桥的嫦娥四号中继星（英文）

The far side of the moon is a unique place for some scientific investigations. Chang'e 4 is a Chinese lunar far side landing exploration mission. Relay communication satellite, named as Queqiao, is an important and innovative part of Chang'e 4 mission. It can provide relay communication to the lander and the rover operating on the lunar far side to maintain their contacts with Earth. It was launched by LM-4 C launch vehicle at the Xichang Satellite Launch Center on May 21, 2018. After five precise orbit controls and a journey of more than 20 days, Queqiao inserted into final halo mission orbit around Earth-moon libration point 2, located about 65,000 km beyond the moon. It is the world's first communication satellite operating in that orbit. Up to now, Queqiao worked very well and provided reliable, continuous communication relay service for the lander and the rover to ensure the mission success of Chang'e 4 exploration mission. Via Queqiao, the lander and the rover were controlled to work by ground stations and obtained a great amount of scientific data. The mission overview, operation orbit selection, relay communication system design and flight profile were introduced in this article.     

基于卫星中继的导弹飞控数据链链路分析

导弹飞控数据链路可极大地提高导弹的作战性能.分析了基于卫星中继的导弹飞控数据链链路特性,给出了其系统组成结构.完成了地星链路和星弹链路系统的分析与设计.最后给出了各链路的通信余量估算.对导弹飞控数据链的工程实现具有参考意义.     

Tracking and data relay satellite system: NASA's new spacecraft data acquisition system

The growth in NASA's ground network complexity and cost triggered a search for an alternative. Through a lease service contract, Western Union will provide to NASA 10 years of space communications services with a Tracking and Data Relay Satellite System (TDRSS). A constellation of four operating satellites in geostationary orbit and a single ground terminal will provide complete tracking, telemetry and command service for all of NASA's Earth orbital satellites below an altitude of 12,000 km. The system is shared: two satellites will be dedicated to NASA service; a third will provide backup as a shared spare; the fourth satellite will be dedicated to Western Union's Advanced Westar commercial service. Western Union will operate the ground terminal and provide operational satellite control. NASA's Network Control Center will provide the focal point for scheduling user services and controlling the interface between TDRSS and the rest of the NASA communications network, project control centers and data processing facilities. TDRSS single access user spacecraft data systems should be designed for efficient time shared data relay support. Reimbursement policy and rate structure for non-NASA users are currently being developed.     

基于ITU—R模型的降雨衰减特性研究与仿真

根据ITU-R雨衰预测模型，给出了静止轨道卫星降雨衰减顸测模型和非静止轨道卫星降雨衰减长期统计值计算方法。结合我国典型地面站的降雨率数据进行的仿真结果表明：所用模型和方法正确。研究对我国卫星通信系统的研究与设计有一定的参考价值。     

微波辐射计静止轨道遥感试验技术

在地球静止轨道上对大气进行微波遥感探测尚无先例。为验证静止轨道微波探测仪器关键技术,研究高轨微波辐射传输特性并积累遥感数据,研制了微波探测试验载荷,搭载于风云四号A星进行在轨试验。微波探测载荷采用真实孔径圆周扫描体系,配置双频段(183,425 GHz)五通道。载荷在轨试验中,各项指标正常,183GHz频段灵敏度优于0.5K,425GHz灵敏度优于1.9K,性能稳定并超过3个月考核寿命。对微波探测载荷183GHz与极轨载荷先进技术微波辐射计(advanced technology microwave sounder,ATMS)进行亮温交叉比对的结果显示,两者亮温相近,变化趋势一致,验证了探测数据的有效性。载荷还在静止轨道获取了极轨无法探知的3K/h量级亮温变化,并在风云四号A星姿态调整期间完成了静止轨道微波遥感成像。验证了在静止轨道上进行真实孔径体制微波遥感探测的有效性。     

嫦娥四号中继星供配电系统设计与应用（英文）

A 28 V-half-regulated power bus topology and an integrated PCDU(Power Conditioning and Distribution Unit) were adopted to meet the energy demand for the Chang'e 4 relay satellite. This paper first introduces the mission features and composition of the PSDS(Power Supply and Distribution System) for the Chang'e 4 relay satellite. Due to this satellite's unusual orbit, operational mode and project restrictions, special analysis and design was conducted on the PSDS from the perspective of weight-reduction, power management, and reliability and so on. Extreme low temperature storage of SA(Solar Array) was considered and how the antenna affects the SA was analyzed. A new kind of high-specific-energy 45 Ah(Ampere-hour) battery cell was used for the first time. To make sure that the satellite would successfully pass the long shadow zones, a 100% DOD(Depth of Discharge) experiment was carried out on the battery. Since the sunlight is almost always available and there are very few times for the battery to charge or discharge, battery care to extend its lifetime is also discussed. PCDU is a device that integrates power conditioning and power distribution in one unit. The PCDU on Chang'e 4 relay satellite can output more power with less weight because of the adoption of a 28 V-half-regulated power bus topology which was also used for the first time and used lighter material for its mechanical framework. Experiment under low temperature on PCDU was conducted as well and a hot backup equalizing charge technique which is beneficial to keep performance of the battery is illustrated. The power distribution module, which is a module of PCDU, enhances the power utilization security by utilizing a static impedance measurement and build-in-test to avoid possible short circuits. As for EED(Electrical Explosive Device) module, a protection plug was specially designed and three switches with different functions were connected in series to prevent the EED from exploding by error. In addition, the allowable minimum EED bus voltage for each EED was evaluated in case of low battery voltage caused by the possible postponement of the launching time. Complete verification experiments on the ground were conducted to confirm the correctness of the design and on-orbit test data conformed to the expected results and theoretical calculation. The power supply and distribution system has been working normally since the day the Chang'e 4 relay satellite was launched into space.     

基于测距观测的静地卫星定轨精度分析

在卫星动力法定轨的协方差分析基础上,提出了一种针对地球静止轨道(GEO)卫星的简化定轨精度分析方法。根据GEO卫星的线性化状态转移方程,通过设定地面跟踪网坐标和卫星星下点经度计算叠加矩阵,由观测弧长和采样间隔直接计算定轨精度评定公式中的主要部分。公式扩展后,能比较各种系统误差源对定轨精度的影响,并将影响较大的作为附加参数纳入估计过程并重新评价定轨精度。用该法对10 m定轨精度的测距跟踪网优化设计和测距偏差对定轨精度的影响特性进行分析的结果表明,测量系统中的系统性误差可能以近20的放大倍率传播到卫星沿迹方向和法向,且不能通过自校准测距常值偏差提高定轨精度。     

“风云二号”静止气象卫星的地面应用系统

简要介绍了“风云二号”静止气象卫星的地面应用系统、主要包括指令控制与数据接收站、数据处理中心、卫星运行控制中心三大组成部分以及三者之间的信息流程，最后介绍了由该系统输出的气象产品。     

卫星双向时间频率传递中的Sagnac效应

 结合卫星双向时间频率传递技术,提出了在卫星运动情况下Sagnac效应解决方案。卫星双向时间频率传递技术是基于地球同步卫星进行的。地球同步卫星在各种摄动力的影响下,相对于地面上的某点不是绝对静止的,而是作小幅度日周期性运动。 Sagnac 效应与卫星和地面观测站的位置密切相关,卫星的运动直接导致了 Sagnac 效应也具有日周期变化的特征。使用高精度实测卫星轨道数据对 Sagnac 效应进行计算分析,结果表明：由卫星运动引起的Sagnac效应值具有与卫星运动一致的周日变化规律特征,大小达到几百皮秒的量级,与传统的将同步卫星作为静止点处理相比,提高了Sagnac效应误差的修正精度。该方案对于各种高精度卫星时间比对技术和卫星导航等领域具有重要的应用价值。     

在轨跟踪与数据中继卫星测控关键技术(上)

根据卫星轨道根数，研究了跟踪与数据中继卫星（TDRS）对用户星的精确跟踪规律，并据此分析了TDRS对卫星平台姿态和天线运动范围的要求。介绍了TDRS测控中的关键技术，如螺旋扫描算法在TDRS搜索用户星时的应用、TDRS对近地卫星的覆盖率、TDRS跟踪多用户星的资源分配准则、星蚀和日凌计算，以及轨道位置保持控制策略等。相关控制策略的正确性已在我国地球同步轨道卫星的在轨测控应用中得到了证实，可用于未来TDRS的工程测控和业务应用。     

一种提高我国空间站中继测控覆盖率的方法

根据中继卫星的定点位置,对我国中继卫星-空间站的几何覆盖率进行了分析,并对提高空间站中继测控覆盖率的途径进行了研究,提出了一种采用不同舱段的2副中继天线融合使用,并通过调整天线安装布局提高中继测控覆盖率的方法。经理论分析和仿真验证,该方法能够有效地提高空间站中继测控覆盖率,可为我国空间站中继天线的安装布局设计提供参考。     

一种绕飞编队卫星星间链路系统的总体设计方法

为了建立高精度相对定位编队卫星的星间链路,提出了一种基于GPS的绕飞编队卫星星间链路系统设计方法。针对我国首次以InSAR为背景的任务,以某绕飞编队星座星间链路系统总体方案为例,利用STK/MATLAB分析软件,对天线覆盖区与组阵进行了仿真分析,并根据分析结果做了系统优化,包括星间轨道构型、天线设计组阵图、天线安装位置、链路预算、星间通信措施设计分析以及电磁兼容性分析等。结果表明:基于GPS的编队卫星能够从系统角度优化设计建立星间链路,从而完成编队跟飞、绕飞期间的星间通信与测量任务,为卫星建立星座构型、相对定位测量提供了可靠、稳定的传输通道。该设计方法可为同类卫星或其他类型卫星星间链路系统设计提供参考。     

深空通信中继下行链路特性研究及仿真分析

在深空通信中,由于信号传输距离遥远,功率受限的下行链路信号衰减巨大。为解决上述问题,分析地球大气层和外层自由空间的传输特性差异,提出以地球同步轨道卫星为中继站的下行链路的构想,根据每一段链路特性的不同选择载波频率。仿真结果表明,中继链路可以提高信号传输的信噪比、增大信道容量、降低误码率,提高了深空通信下行链路的可靠性。     

Technical and economical comparison between a modular geostationary space platform and a cluster of satellites

In recent years, the identification of a large number of telecommunication missions reflects a growing demand for the provision of a large variety of communications and data transmission services performed by a space segment.

At present, communication space segment use a single operational satellite per orbit position. However, the expected increase of communication channels per space segment will lead to a corresponding increase of satellite mass and size which could exceed the capabilities of existing launch vehicles in terms of mass and volume requirements. Those considerations, coupled with the threatening saturation of the geostationary orbit, lead to the conclusion that an optimal space segment concept must be defined on a technical as well as economical point of view.

Two main concepts may be envisaged: one is a large platform, which can be assembled either in geostationary orbit (resulting in several launches, rendez-vous and docking), or in low earth orbit by using the STS; the other concept is a cluster of satellites.

These candidate concepts are designed to meet the requirements of a reference mission. They are characterized by the required number of modules to be launched, the type of launcher, the new subsystems or equipments to be developed. The concepts are evaluated following technical criteria such as adaptability to other missions, flexibility, growth potential. A cost/benefit evaluation of each solution is presented. A comparison between the different concepts is then made on the basis of the technical/economical attractiveness of each solution.