基于目标运动特性的多功能混合星座设计方法

针对地面探测目标的运动特性,结合卫星有效载荷的功能特点,提出了一种由携带不同有效载荷、功能相似的卫星组合而成的卫星星座的设计方法,并以对太平洋海域运动目标的探测为例,设计了一个多功能混合探测卫星星座。通过仿真分析可知,该混合星座对海上运动目标具有较好的探测识别性能。     

New low-earth orbit satellites authentication and group key agreement protocol

Due to the function of communication and continuous monitoring,the low-earth orbit satellites are widely used in the aerospace field.However,there is no special authentication protocol in the existing satellite communication system.In order to solve this problem,a lightweight authentication protocol which considering the switch of communication path in the authentication process was designed for the low-earth orbit satellites,and the proposed protocol was verified by simulation and compared with the 3GPP AKA protocol.The simulation results show that the protocol has a 20% higher efficiency than 3GPP AKA protocol,and the spend of group key agreement protocol is about 300 ms.     

Improved least mean square algorithm based in satellite multi-beamforming

High-throughput satellites use multi-beam technology to achieve polarization isolation and spatial isolation to reuse frequency resources,resulting in increased traffic capacity,but this presents a higher demand for fast adaptive beamforming algorithms.In order to solve the shortcoming that the convergence rate and steady-state error can not be satisfied simultaneously when using the LMS algorithm,an improved least mean square algorithm was proposed,which used the statistical average gradient update to solve the problem of the formation of beam instability caused by the instantaneous gradient,which can speed up at the beginning of the beamforming and maintain a small error value after the convergence has reached a steady state.The use of 61-element hexagonal array phased array antenna to form a 7-point beam in an environment where high-throughput satellites have a strong rainfall attenuation was considered.The results show that the improved algorithm can greatly improve the convergence speed and obtain better steady state performance under the condition of only a small increase in complexity,which can be applied to high-throughput satellite beamforming technology with severe inter-beam co-channel interference in emergency communication scenarios.     

紫外-可见光谱水质检测系统的多束LED光纤耦合研究

针对紫外-可见光谱水质检测系统单个LED光源输出功率低、光束质量差的问题,提出了一种多束紫外LED光源与光纤合束耦合的结构设计方案.运用ZEMAX光学分析软件开展了仿真设计研究,针对紫外LED光源与光纤耦合发散角较大的问题,设计了非球面准直透镜,准直后发散角为0.403 mrad;针对光束尺寸与光纤的匹配问题,进行了消色差双分离聚焦耦合透镜的设计.实验结果表明,合束LED光束汇聚的弥散斑的RMS尺寸为186.412 μm,GEO点尺寸为290.071 μm,光束中95％以上的能量集中在300μm以内,实现了多束LED光源与光纤的高效耦合.     

基于3D打印的Ku/Ka频段双波束天线设计

提出一种采用3D打印技术设计制造的径向开孔分层龙伯透镜天线, 该天线以低损耗的石蜡强化聚苯乙烯为基材, 透镜直径为700 mm, 结构形式为7层半球龙伯透镜.天线工作在Ku/Ka频段, 可同时对准两个目标.研究表明:采用3D打印技术制造的低损耗介质径向开孔分层龙伯透镜天线实现了较高性能, 有效解决了传统加工方式加工困难、一致性差的问题, 可以容易地通过采用更小介电损耗的材料实现更优良的天线性能.     

双曲结构VFDF雷达干扰宽带多波束形成技术

采用一种高效的双曲结构可变分数延时滤波器（V FD F ）实现了宽带波束形成,可以在不改变滤波器系数的情况下改变波束指向,并采用这种可变分数延时滤波器实现了雷达干扰宽带多波束形成,通过共用子滤波器减小了硬件开销。     

多波束干扰系统干扰资源综合管理算法

针对先进战机多波束干扰系统同时干扰多部雷达时的资源管理问题,采用多属性决策 方法建立了战机电子对抗系统威胁等级评估模型,并与神经元模型相结合建立了干扰任务请求模 型;针对干扰资源的限制,对目标雷达进行分类,当需要且能够干扰的雷达数目超出干扰波束数目 时,建立了干扰任务整合模型,并采用C-means 算法对模型进行求解;最后提出了多波束干扰系统 同时干扰多部雷达时的资源管理算法。对目标进行分类和对干扰任务进行整合可以提高多波束干 扰系统的效率,提升干扰系统的智能化水平。     

Novel statistical method for data drift detection in satellite telemetry

Autonomy is becoming a prime requirement for satellite mission control operations. Data-driven methods like Machine Learning models are playing a key role in bringing in autonomy. Health keeping data from satellite telemetry is a key ingredient in these data-driven methods. In real-world satellite operations, the health-keeping telemetry data gradually drifts due to adverse space weather effects and wear and tear of electronic and mechanical components. The key question that arises is how to detect and quantify the data drift which is generally a gradual phenomenon. This paper discusses a novel statistical method for detecting data drift occurring in satellite telemetry. For the purpose of experimental work in this paper, an actual telemetry data set of the BUS CURRENT sensor which is part of the Electrical Power System of a Low Earth Orbit Satellite was considered. Data drift detection test was carried out using this sensor data using the developed novel statistical method and with Kolmogorov Smirnov test which is a probabilistic method. Both results are analysed and compared. Thereafter novel statical method was used to check its efficacy using a synthetic data set with induced drift.     

Statistical channel modelling and performance evaluation in satellite personal communications

This paper is concerned with channel modelling for satellite personal communications and with the associated problem of performance evaluation. Channel characteristics for personal communications tend to differ from those traditionally accepted for vehicular communications. In this paper we report on modelling aspects for both wideband and narrowband personal communications. Then we consider performance evaluation for low-altitude earth orbit (LEO) satellite systems in terms of bit error probability and outage probability. To evaluate the outage probability for LEO systems, a tight and simple upper bound is finally provided. © 1998 John Wiley & Sons, Ltd.     

分布式卫星INSAR信号的相关性分析

在考虑斜视和轨道不平行的情况下,推导了干涉合成孔径雷达(INSAR)信号相关系数的表达式,据此说明了各种去相关因素产生的原因和相互关系,定量分析了分布式卫星INSAR系统中多普勒中心去相关、轨道不平行去相关、基线去相关、体散射去相关等去相关因素的作用大小;结合分布式卫星INSAR系统的多基线特点,提出了利用多基线数据融合提高信号相关性的有效措施。分析结果表明,通过合理设计和有效信号处理,分布式卫星INSAR系统可以获取可靠的干涉测量结果。