脉冲多普勒雷达导引头遮挡问题解决方法研究

分析了脉冲多普勒雷达导引头“遮挡”效应产生的原因,介绍了锵决“遮挡”的两种方法：记忆跟踪法和变PRF方法,提出了采用四种重频脉冲交替变换解决遮挡的方法,同时该方法能有效的解决导引头测距模糊问题。最后利用MATLAB软件对四重频脉冲进行了时域仿真,并对该方案进行了硬件实现。     

Ionospheric total electron content response to annular solar eclipse on June 21, 2020

The effects of physical events on the ionosphere structure is an important field of study, especially for navigation and radio communication. The paper presents the spatio-temporal ionospheric TEC response to the recent annular solar eclipse on June 21, 2020, which spans across two continents, Africa and Asia, and 14 countries. This eclipse took place on the same day as the June Solstice. The Global Navigation Satellite System (GNSS) based TEC data of the Global Ionosphere Maps (GIMs), 9 International GNSS Service (IGS) stations and FORMOSAT-7/COSMIC-2 (F7/C2) were utilized to analyze TEC response during the eclipse. The phases of the TEC time series were determined by taking the difference of the observed TEC values on eclipse day from the previous 5-day median TEC values. The results showed clear depletions in the TEC time series on June 21. These decreases were between 1 and 9 TECU (15–60%) depending on the location of IGS stations. The depletions are relatively higher at the stations close to the path of annular eclipse than those farther away. Furthermore, a reduction of about ?10 TECU in the form of an equatorial plasma bubble (EPB) was observed in GIMs at ~20° away from the equator towards northpole, between 08:00–11:00 UT where its maximum phase is located in southeast Japan. Additionally, an overall depletion of ~10% was observed in F7/C2 derived TEC at an altitude of 240 km (hmF2) in all regions affected by the solar eclipse, whereas, significant TEC fluctuations between the altitudes of 100 km ? 140 km were analyzed using the Savitzky-Golay smoothing filter. To prove TEC depletions are not caused by space weather, the variation of the sunspot number (SSN), solar wind (V_SW), disturbance storm-time (Dst), and Kp indices were investigated from 16th to 22nd June. The quiet space weather before and during the solar eclipse proved that the observed depletions in the TEC time series and profiles were caused by the annular solar eclipse.     

小步长低阶Collocation方法轨道积分性能研究

介绍了Collocation方法的原理及误差构成,以Collocation方法在逐历元滤波轨道解算中的应用为切入点对小步长低阶Collocation方法轨道积分的性能进行了研究。分别就二体问题及真实GPS星座卫星轨道为对象进行了一系列验算,得到了一些有益结论：就积分方法本身性能而言,Collocation积分方法较传统数值积分法精度要高且稳定性要好;在一定长度的积分步长范围内,将小步长低阶Collocation方法用于滤波轨道解算是可行且有效的。 但在积分步长很小的情形下,从计算效率方面考虑,不推荐使用Collocation方法;利用小步长低阶Collocation方法取代大步长高阶方法能提高效率且可抑制蚀现象引起的积分结果发散。经试验表明：选用积分步长为900s的4阶方法是合适的。     

基于Eclipse的航天嵌入式软件集成 开发环境设计与实现

针对当前航天器软件研制过程中需要使用多种开发工具的问题,设计实现了集工程管理、代码编辑、语法检查、编译链接和调试测试于一体的航天嵌入式软件集成开发环境.研究成果已应用于航天器嵌入式软件的研发,缩短了软件研发周期并提高了软件质量,同时也为软件集成开发环境的研发提供借鉴.     

航空电子系统分区间通信监控技术的研究和实现

当今基于ARINC653的综合化航空电子系统的应用日益广泛,分区作为ARINC653提出的任务调度和资源共享的核心概念,其相互间通信的可靠性和安全性成为航空电子系统要解决的重要问题.详细阐述了分区间通信监视的原理,并给出了一种可行的分区间通信监视器设计和实现方案.应用表明分区间通信监视器极大地改善和提高了航空电子系统的通信监控能力,为通信故障诊断和分析提供了依据.     

基于GEF框架的AFDX网络建模工具的设计与实现

本文提出了基于Eclipse GEF框架的AFDX网络建模方法。该方法应用GEF的MVC结构,以RCP的形式实现了图形化的AFDX网络建模工具,为用户提供了高效的展示和编辑AFDX网络模型的环境。由于建立了基于Eclipse RCP技术的开放性平台,用户可以Eclipse插件的形式将任何新的功能无缝地集成在此平台下,极大地提高了工具的可扩展性。     

A shadow function model based on perspective projection and atmospheric effect for satellites in eclipse

Accurate Solar Radiation Pressure (SRP) modelling is critical for correctly describing the dynamics of satellites. A shadow function is a unitless quantity varying between 0 and 1 to scale the solar radiation flux at a satellite’s location during eclipses. Errors in modelling shadow function lead to inaccuracy in SRP that degrades the orbit quality. Shadow function modelling requires solutions to a geometrical problem (Earth’s oblateness) and a physical problem (atmospheric effects). This study presents a new shadow function model (PPM_atm) which uses a perspective projection based approach to solve the geometrical problem rigorously and a linear function to describe the reduction of solar radiation flux due to atmospheric effects. GRACE (Gravity Recovery And Climate Experiment) satellites carry accelerometers that record variations of non-conservative forces, which reveal the variations of shadow function during eclipses. In this study, the PPM_atm is validated using accelerometer observations of the GRACE-A satellite. Test results show that the PPM_atm is closer to the variations in accelerometer observations than the widely used SECM (Spherical Earth Conical Model). Taking the accelerometer observations derived shadow function as the “truth”, the relative error in PPM_atm is ?0.79% while the SECM 11.07%. The influence of the PPM_atm is also shown in orbit prediction for Galileo satellites. Compared with the SECM, the PPM_atm can reduce the radial orbit error RMS by 5.6?cm over a 7-day prediction. The impacts of the errors in shadow function modelling on the orbit remain to be systematic and should be mitigated in long-term orbit prediction.     

基于天基光学观测的空间目标可见性分析

基于天基光学观测的空间目标可见性分析是天基空间监视系统中的关键问题之一。对基于天基光学观测的单颗监视卫星,本文综合考虑其几何可见性、光学可见性和设备可见性,建立了获取其实际可观测区域的数学模型,并给出了仿真计算结果。     

基于Eclipse平台的嵌入式软件集成开发环境目标机通信管理

基于Eclipse平台的嵌入式软件集成开发环境已经成为嵌入式软件集成开发环境的主流。嵌入式软件集成开发环境中的各种交叉开发工具依赖于目标机服务器提供的目标机通信管理功能。提出了一种目标机通信管理系统结构,描述了其各功能部件的功能和接口及其主要的工作流程,介绍了其软件架构及其主要的难点技术与解决方法。     

The GLONASS-M satellite yaw-attitude model

The proper modeling of the satellites’ yaw-attitude is a prerequisite for high-precision Global Navigation Satellite System (GNSS) positioning and poses a particular challenge during periods when the satellite orbital planes are partially eclipsed. Whereas a lot of effort has been put in to examine the yaw-attitude control of GPS satellites that are in eclipsing orbits, hardly anything is known about the yaw-attitude behavior of eclipsing GLONASS-M satellites. However, systematic variations of the carrier phase observation residuals in the vicinity of the orbit’s noon and midnight points of up to ±27 cm indicate significant attitude-related modeling issues. In order to explore the GLONASS-M attitude laws during eclipse seasons, we have studied the evolution of the horizontal satellite antenna offset estimates during orbit noon and orbit midnight using a technique that we refer to as “reverse kinematic precise point positioning”. In this approach, we keep all relevant global geodetic parameters fixed and estimate the satellite clock and antenna phase center positions epoch-by-epoch using 30-second observation and clock data from a global multi-GNSS ground station network. The estimated horizontal antenna phase center offsets implicitly provide the spacecraft’s yaw-attitude. The insights gained from studying the yaw angle behavior have led to the development of the very first yaw-attitude model for eclipsing GLONASS-M satellites. The derived yaw-attitude model proves to be much better than the nominal yaw-attitude model commonly being used by today’s GLONASS-capable GNSS software packages as it reduces the observation residuals of eclipsing satellites down to the normal level of non-eclipsing satellites and thereby prevents a multitude of measurements from being incorrectly identified as outliers. It facilitates continuous satellite clock estimation during eclipse and improves in particular the results of kinematic precise point positioning of ground-based receivers.