短基线动态相对定位中GPS单历元解算整周模糊度方法

针对短基线动态相对定位中快速解算整周模糊度的难题，提出了一种新的方法——GPS单历元解算整周模糊度。文中对相关的观测方程、载波相位的观测精度、真假解的识别等问题进行了详细讨论。试验证明，该方法正确、可靠，解决了快速解算整周模糊度这个难题，克服了传统方法需要进行静态初始化等问题。将该方法应用在车辆、舰船等移动载体上，可以实现真正意义上的实时动态相对定位，具有重要的应用价值。     

航空发动机排气温度基线建模新方法研究

为实现航空发动机气路性能诊断与预测,提出一种基于堆叠降噪自编码器(Stacked de?noising auto encoder,SDAE)和支持向量回归(Support vector regression,SVR)相结合的航空发动机排气温度(Exhaust gas temperature,EGT)基线建模方法.以CF...     

A multiple-CubeSat constellation for integrated earth observation and marine/air traffic monitoring

CubeSats has evolved from purely educational tools, to useful platforms for technology demonstration and many practical applications. This paper reviews a CubeSat constellation mission involving 3 CubeSats launched into orbit on Sep. 25th 2015, aiming to demonstrate the integrated application of low-cost CubeSat technologies with distributed payloads using a group of satellites, as well as to demonstrate several new technologies. The mission scenario, the satellite system design, the innovative technologies and instruments or devices used on the CubeSats and the in-orbit experimental results and the payload data analysis, as well as some experiences and lessons learned, are presented and summaried.     

一种兼顾卫星导航系统星间观测及通信的链路分配算法

卫星导航系统星间采用点波束建立星间链路时,由于星上波束数量小于可建立星间链路的卫星数量,因此便产生了如何有效分配有限波束来建立星间链路的问题。针对该问题首先利用星座运行的周期性提出了一种适用于星间观测及星间通信的拓扑处理方式,并以该拓扑处理方式为基础提出了一种链路分配算法。算法在保证星间观测数量最大化的前提下,以降低整网通信代价为优化目标,尽管为了保证星间观测数量会不可避免地导致通信性能的部分损失,但是仿真结果表明算法的性能整体上优于铱星系统所采用的网状链路分配方法的性能。     

基于CMMI的配置管理系统设计与实现

在研究软件配置管理方法的基础上,结合CMMI配置管理要求以及航天测控软件配置管理实际需求,建立配置管理实施框架,实现了一个一体化的配置管理系统。该系统能够辅助开发人员和配置管理人员便捷地制定配置管理计划,进行配置标识、建立和发布基线、跟踪和控制更改、执行配置审核和报告的自动生成,实现了CMMI对软件配置管理的要求,提高了配置管理的自动化管理水平和易用性。     

Characteristics and accuracies of the GRACE inter-satellite pointing

For almost 10 years, the Gravity Recovery and Climate Experiment (GRACE) has provided information about the Earth gravity field with unprecedented accuracy. Efforts are ongoing to approach the GRACE baseline accuracy as there still remains an order of magnitude between the present error level of the gravity field solutions and the GRACE baseline. At the current level of accuracy, thorough investigation of sensor related effects is necessary as they are one of the potential contributors to the error budget. In the science mode operations, the twin satellites are kept precisely pointed with their KBR antennas towards each other. It is the task of the onboard attitude and orbit control system (AOCS) to keep the satellites in the required formation. We analyzed long time series of the inter-satellite pointing variations as they reflect the AOCS performance and characteristics. We present significant systematic effects in the inter-satellite pointing and discuss their possible sources. Prominent features are especially related to the magnetic torquer characteristics, star cameras’ performance and KBR antenna calibration parameters. The relation between the magnetic torquer attitude control and the Earth magnetic field, impact of the different performance of the two star camera heads on the attitude control and the features due to uncertainties in the calibration parameters relating the star camera frame to K-frame are discussed in detail. Proper understanding of these effects will help to reduce their impact on the science data and subsequently increase the accuracy of the gravity field solutions. Moreover, understanding the complexity of the onboard system is essential not only for increasing the accuracy of the GRACE data but also for the development of the future gravity field satellite missions.     

Flight performance analysis of GRACE K-band ranging instrument with simulation data

A dual one-way ranging (DOWR) system provides very high accuracy range measurements between two satellites. The GRACE satellite mission implements the DOWR, called KBR (K-band ranging), to measure very small inter-satellite range change in order to map the Earth gravity field. The flight performance of the KBR is analyzed by using a hybrid software simulator that incorporates actual satellite orbit data into a comprehensive KBR simulator, which was earlier used for computing the GRACE baseline accuracy. Three types of experiments were performed. First is the comparison of the flight data with the simulated data in spectral domain. Second is the comparison of double differenced noise level. Third is the comparison of the range-rate difference with GPS clock estimates. The analysis shows a good agreement with the simulation model except some excessive high frequency noise, e.g. 10⁻⁴ m/√Hz at 0.1 Hz. The range-rate difference shows 0.003 cyc/s discrepancy with the clock estimates. These analyses are helpful to refine the DOWR simulation model and can be benefit to future DOWR instrument development.     

基于射频的导航卫星星间链路信息传输与仿真研究

星间链路是导航卫星实现精密定轨和自主导航的关键技术之一。导航卫星通过星间链路完成伪距测量和数据交换,维持系统稳定运行的时空基准,保证系统持续提供精准导航服务。根据全球导航卫星系统的建设情况和发展趋势,首先介绍星间观测和信息传输频段,并从天线特征、多址控制方式和网络拓扑结构等角度分析了射频链路的工作体制。最后,针对实际导航卫星星座,应用OPNET平台建立导航信息传输仿真模型,通过分析信息传输效率,验证了基于射频链路导航信息传输的可行性和有效性,对全球导航卫星系统的星间链路研究具有一定的参考价值。     

星间链路测量中的载波相位测距算法研究

运用双频伪码/载波相位组合方式求解整周模糊度的方法实现星间链路中的载波相位测距。在双频伪码/载波相位组合原理的基础上,对不同组合方式下的测量误差进行分析,并研究了增大载波频率时的载波相位测距手段。仿真结果表明,算法能得到较准确的整周模糊度值和精度较高的测距值,实现了载波相位高精度测距。