Mega-Constellations Based TT&C Resource Sharing: Keep Reliable Aeronautical Communication in an Emergency

With the development of the transportation industry, the effective guidance of aircraft in an emergency to prevent catastrophic accidents remains one of the top safety concerns. Undoubtedly, operational status data of the aircraft play an important role in the judgment and command of the Operational Control Center(OCC). However, how to transmit various operational status data from abnormal aircraft back to the OCC in an emergency is still an open problem. In this paper, we propose a novel Telemetry, Tracking,and Command(TT&C) architecture named Collaborative TT&C(CoTT&C) based on mega-constellation to solve such a problem. CoTT&C allows each satellite to help the abnormal aircraft by sharing TT&C resources when needed, realizing real-time and reliable aeronautical communication in an emergency. Specifically, we design a dynamic resource sharing mechanism for CoTT&C and model the mechanism as a single-leader-multi-follower Stackelberg game. Further, we give an unique Nash Equilibrium(NE) of the game as a closed form. Simulation results demonstrate that the proposed resource sharing mechanism is effective, incentive compatible, fair, and reciprocal. We hope that our findings can shed some light for future research on aeronautical communications in an emergency.

一种航天测控冗余跟踪弧段处理方法

随着在轨航天器的日益增多,测控资源的需求量也日益增大,因此,其使用效率也倍受关注。当航天器重要测控弧段安排多个测控设备进行全力跟踪时,很容易出现测控弧段搭接或完全被覆盖的情况。为有效利用现有测控资源,针对弧段搭接的情况,提出了一种基于冗余度评价函数的跟踪弧段处理方法,该方法在不降低跟踪总时长情况下,通过合理有效地配置测控资源,剔除了冗余跟踪弧段,提高了现有测控资源的使用效率。

基于遗传算法的TT&C测控资源优化调度(英文)

TT&C测控资源调度是一个涉及卫星、测控站以及调度准则等多方面因素的复杂优化问题。针对这一优化问题,根据测控调度的一般原则和优化准则,建立了相应的优化模型,并给出了基于遗传算法求解该问题的方法和步骤;最后,通过两个示例分析,演示验证了该方法对于解决一般测控调度问题的有效性。

带局部交互的多星TT&C调度合作协同进化

针对现有合作协同进化机制较少利用局部协同信息的问题,通过对多星TT&C资源调度的合作协同进化求解进行改进,在全局协同的基础上加强局部交互,为每个个体设定一个表明其与所有相邻子种群合作效果的进化性能指标——局部交互值,将该值作为选择操作中衡量个体优劣的尺度之一,以局部交互值与各子适应度之和的差值决定个体变异率,使变异具有自适应性,从而减少由子种群代表个体选择的非全局性造成的优秀个体丢失现象。仿真实验结果表明该方法能较好地提高求解质量。

TT&C系统中测距误差的频率特性分析法

以往的文献中,多用群时延来分析TT&C的测距误差,这种方法不够准确和全面。本文采用幅、相频率特性和相位波动特性来分析TT&C信道中的测距误差。详细讨论了由于信道频率特性和相位波动特性变化产生的测距误差,给出了测距侧音相位的数学表达式。运用这些公式可以计算出这些因素对测距漂移误差的影响,提高测距精度。

航天TT&C调度的拉格朗日松弛策略

根据航天遥测、跟踪和指挥(TT&C)调度的测控需求,建立航天测控调度问题的0-1整数规划模型,运用(λ,ν)、(μ,ν)和(λ,μ)3种策略对模型中的约束进行松弛,通过次梯度优化算法求得每种松弛问题的上界。利用2个场景验证上界(目标函数值)的有效性,调度结果表明,3种松弛策略中以次梯度优化算法得到的上界差别最小。

Networked TT&C for Mega Satellite Constellations:A Security Perspective

Satellite constellations are promising in enabling the global Internet.However,the increasing constellation size also complicates tracking,telemetry and command(TT&C)systems.Traditional groundbased and space-based approaches have encountered significant obstacles due to,e.g.,the limited satellite visible arc and long transmission delay.Considering the fast development of intersatellite communications,synergy among multiple connected satellites can be exploited to facilitate TT&C system designs.This leads to networked TT&C,which requires much less predeployed infrastructures and even performs better than traditional TT&C systems.In this paper,we elaborate system characteristics of networked TT&C compared with traditional ground-based and spacebased TT&C,and propose the unique security challenges and opportunities for networked TT&C,which includes secure routing and trust mechanisms.Furthermore,since networked TT&C is a novel scenario with few relevant researches,we first investigate the current researches on secure routing and trust mechanisms for traditional terrestrial and satellite networks,and then accordingly deliver our security perspectives considering the system characteristics and security requirements of networked TT&C.

Beamforming of Whole Airspace Phased Array TT&C System Based on Linear Subarrays

The whole airspace phased array telemetry,track and command(TT&C)system is regarded as the development tendency of next generation TT&C system,and the distribution of the antenna units and the beamforming technology have sparked wide interest in this field.A method for antenna distribution is proposed based on the linear subarrays technology.A symmetrical truncated cone conformal array is composed of the linear subarrays placed on the generatrix.The impact of truncated cone bottom radius and elevation angle on beamforming are studied and simulated.Simulation results verify the system design.

Method to Realize TT&C of Spacecraft In-Orbit from Ground-Based to Space-Ground-Based Mode

Currently, TT&C of spacecraft is performed by a ground system. Because more and more spacecrafts are launched into orbits, it is difficult for the ground system to meet the TT&C requirements of the spacecrafts. To explore a new, effective and economical TT&C mode is absolutely necessary. A method is proposed to use SGBM mode in TT&C spacecrafts in low earth orbits, here. Firstly, the principle of the mode is discussed; secondly, the system to simulate the mode is designed; thirdly, the relative issues to use the mode are indicated; fourthly, the experimental results (simulation) to apply the mode to TT&C spacecrafts are analyzed; and finally dawn is the main conclusion of the method.

Continuous-Wave Interference Mitigation for Acquisition Method in Unified Carrier TT&C Systems

An interference mitigation for acquisition method,based on both energy center and spectrum symmetry detection,has been proposed as a possible solution to the problem of signal acquisition susceptibility to continuous-wave interference(CWI)in unified carrier telemetry,tracking,and command(TT&C)systems.With subcarrier modulation index as a priori condition,the existence of CWI is determined by comparing the energy center with the symmetric center.In the presence of interference,the interference frequency point is assumed and culled;sequentially,the spectral symmetry is used to verify whether the signal acquisition is realized.Theoretical analysis,simulations,and experimental results demonstrate that the method can realize the acquisition of the main carrier target signal with an interference-to-signal ratio of 31 dB,which represents an improvement over the existing continuous-wave interference mitigation for acquisition methods.

Introduction to the TT&C Scheme for Chang’e⁃5 Mission

Chang’e-5 mission is China’s first lunar sample return mission.It contains several new flight phases compared with the previous lunar missions,such as the lunar take-off and orbit insertion phase,the rendezvous and docking phase,etc.Chang’e-5 mission is extremely complicated and full of new challenges.This paper sorts out the characteristics and the difficulties in telemetry,tracking,and command(TT&C)of Chang’e-5 mission.The main technical contribution is a reliable general design of the TT&C system,including the application of X-band TT&C in launch and early orbit phase(LEOP),multiple targets simultaneous TT&C in X-band,lunar surface benchmark calibration,high-precision and rapid orbit trajectory determination for the lunar surface take-off,remote guidance rendezvous and docking,the determination of the initial navigational value for the separation point of the Chang’e-5 orbiter and returner,and the design of the reentry measurement chain.Based on this scheme,a global deep space TT&C network and interplanetary reentry measurement chain have been established for China,and near-continuous TT&C support for China’s first extraterrestrial object sampling and return mission has been realized,ensuring reliable tracking,accurate measurement and accurate control.The global deep space network can provide TT&C support comparable to that of National Aeronautics and Space Administration(NASA)and European Space Agency(ESA)for subsequent lunar and deep space exploration missions.The techniques of rapid trajectory determination of lunar take-off and orbit entry,as well as high precision and remote guidance of lunar orbit rendezvous and docking can lay a technological foundation for the future manned lunar exploration missions and planetary sampling and return missions.

China’s Global Space-based TT&C Network System Established

The Tianlian 1-03 satellite, the third geosynchronous data relay satellite of China, was successfully launched into space on a LM-3C launch vehicle from the Xichang Satellite Launch Center at 23:43 Beijing time on July 25. Twenty-six minutes after the liftoff, the satellite

Approach to Improving TT&C Coverage Rate of LEO and MEO Spacecrafts in China

With the rapid increase of number and types of Low Earth Orbit (LEO) and Medium Earth Orbit (MEO) spacecrafts in China, the insufficiency of TT&C resources is exposed.How to improve LEO and MEO TT&C coverage rate has become the key problem of TT&C system,which should be resolved urgently. Firstly,the basic concepts of TT&C coverage are discussed and the relation between TT&C coverage of ground station and geography latitude of ground station as well as spacecraft altitude are analyzed. Secondly,the United States NASA TT&C network is taken as an instance to describe the developing process of TT&C network. Finally,in combination with TT&C activities of LEO and MEO spacecrafts in China,the method to heighten TT&C coverage rate is put forward,such as rational establishing station,space resources application,international TT&C cooperation etc.

Rapid Launch of Medium-Sized Solid Carrier Rockets at Sea With High Reliability and Convenient Intelligence

Gravity-1 solid-propellant carrier rocket utilizes a three-vertical testing and launch mode, and adopts a sea-based launch method. As the demand for satellite launches continues to grow, the scarcity of launch site resources,and the consideration of cost savings, the need for rapid testing and launch of carrier rockets has become increasingly strong. The capability of rapid testing and launch has even become one important aspect of evaluating a rocket. This paper focuses on the characteristics of the Gravity-1 solid-propellant strap-on medium-sized carrier rocket and designs and implements a highly reliable, convenient, and intelligent low-cost rapid testing and launch solution. The main aspects include the design of a highly reliable dual-redundant ground architecture and the application of ground-based shelf products.

Hierarchical Disturbance Propagation Mechanism and Improved Contract Net Protocol for Satellite TT&C Resource Dynamic Scheduling

The practical engineering of satellite tracking telemetry and command(TT&C)is often disturbed by unpredictable external factors,including the temporary rise in a significant quantity of satellite TT&C tasks,temporary failures and failures of some TT&C resources,and so on.To improve the adaptability and robustness of satellite TT&C systems when faced with uncertain dynamic disturbances,a hierarchical disturbance propagation mechanism and an improved contract network dynamic scheduling method for satellite TT&C resources were designed to address the dynamic scheduling problem of satellite TT&C resources.Firstly,the characteristics of the dynamic scheduling problem of satellite TT&C resources are analyzed,and a mathematical model is established with the weighted optimization objectives of maximizing the revenue from task completion and minimizing the degree of plan disturbance.Then,a bottom-up distributed dynamic collaborative scheduling framework for satellite TT&C resources is proposed,which includes a task layer,a resource layer,a central internal collaboration layer,and a central external collaboration layer.Dynamic disturbances are propagated layer by layer from the task layer to the central external collaboration layer in a bottom-up manner,using efficient heuristic strategies in the task layer and the resource layer,respectively.We use improved contract network algorithms in the center internal collaboration layer and the center external collaboration layer,the original scheduling plan is quickly adjusted to minimize the impact of disturbances while effectively completing dynamic task requirements.Finally,a large number of simulation experiments were carried out and compared with various comparative algorithms.The results show that the proposed algorithm can effectively improve the solution effect of satellite TT&C resource dynamic scheduling problems,and has good application prospects.

M-Rife频率估计法在测控信号载波捕获中的应用

针对航天测控对载波快速捕获的需求,设计一种能够实现载波快速捕获的方法,即先对导频信号进行频率估计,再将估计得到的频率值置入后续的科斯塔斯环进行处理。Rife频率估计方法的估计误差接近克拉美-罗限,但是当信噪比较低或载波频率在频率分辨率整数倍附近时,此方法有较大的估计误差。为了提高导频信号的频率估计精度,采用修正Rife(M-Rife)频率估计方法。对M-Rife频率估计方法的性能进行仿真分析,并与Rife频率估计方法进行对比,结果表明M-Rife频率估计方法可以有效地提高频率估计精度和稳定度。

扩频统一测控系统的PN码捕获

扩频体制的统一测控系统(TT&C)实现遥测、遥控、测距、跟踪、数字通信等多种功能统一以及多站测量和多目标测量的统一,其实质是利用PN码的相关性实现CDMA。多普勒效应和数据调制对PN码的同步捕获和跟踪的影响很大,此时PN码的捕获成为系统实现的关键。

船载X频段测控雷达跟踪S频段飞行器的适应性设计

为了挖掘船载X频段测控雷达的设备潜能,解决船摇情况下X频段卫星信号的窄波束角度捕获的难题,提出了利用船载X频段测控雷达跟踪S频段接收信号进行自引导的设计方案。对S/X双频馈源进行测试,并在X频段下行链路分析的基础上进行S频段链路的设计,设计出满足系统G/T值的下行链路配置,通过跟踪风云气象卫星进行功能验证和跟踪精度分析,证明该设计方案技术可行,满足指标。

多音干扰下DS/FH扩频测控信号伪码跟踪误差分析与仿真

分析扩频测控信号在干扰环境下的性能对测控体制的研究具有重要的意义。推导音调干扰环境下DS测控信号的伪码跟踪误差表达式,以Matlab/Simulink为平台搭建了伪码跟踪性能仿真平台,仿真分析了不同干扰条件、不同增益分配下的DS/FH混扩测控信号伪码跟踪性能,验证了理论推导的正确性,为进一步研究提供了参考。

随机二元码调制噪声干扰下DS/FH混合扩频测控信号检测性能分析与仿真

分析DS/FH混合扩频测控信号在干扰环境下的性能对该新测控体制的研究具有重要的意义。推导随机二元码调制干扰环境下DS/FH测控信号的检测概率和虚警概率表达式,并以Matlab/Simulink为平台搭建检测性能仿真系统,采用恒虚警检测准则仿真分析不同直扩、跳频增益组合在不同干扰条件下的检测性能,验证了理论推导的正确性,为进一步研究提供了参考。