Data processing center of RadioAstron space VLBI project

In this paper, questions on development, implementation, and operation of RadioAstron project Data Processing Center (DPC) are reviewed. The main components of the dedicated DPC are the computer complex with 1 TFlops/s performance, storage with memory capacity of approximately 10 PB, the network infrastructure, and the corresponding communication channels. Performance enhancement methods and resolution of information storage, archiving, and process problems of space VLBI high-speed digital data flows are analyzed. It is shown that successful operation of DPC is mainly provided by optimal organization of computer system structure, storage, and networking transmission. Some of the important key features of RadioAstron project DPC and its comparative differences from the standard VLBI procedures are considered.     

Reconciling space object observed and solar pressure albedo-areas via astrometric and photometric data fusion

There are many Resident Space Objects (RSOs) in the Geostationary Earth Orbit (GEO) regime, both operational and debris. The primary non-gravitational force acting on these RSOs is Solar Radiation Pressure (SRP), which is sensitive to the RSO’s area-to-mass ratio. Sparse observation data and mismodeling of non-gravitational forces has constrained the state of practice in tracking and characterizing RSOs. Accurate identification, characterization, tracking, and motion prediction of RSOs is a high priority research issue as it shall aid in assessing collision probabilities in the GEO regime, and orbital safety writ large. Previous work in characterizing RSOs has taken a preliminary step in exploiting fused astrometric and photometric data to estimate the RSO mass, shape, attitude, and size. This works, in theory, since angles data are sensitive to SRP albedo-area-to-mass ratio, and photometric data are sensitive to shape, attitude, and observed albedo-area. By fusing these two data types, mass and albedo-area both become observable parameters and can be estimated as independent quantities. However, previous work in mass and albedo-area estimation has not quantified and assessed the fundamental physical link between SRP albedo-area and observed albedo-area. The observed albedo-area is always a function of the SRP albedo-area along the line of sight of the observer. This is the physical relationship that this current research exploits. It is shown through simulation that due to this physical link, and through the fusion of astrometric and photometric data, it is possible to observe the mass of a space object when the area is not known. Results for data from 100 trajectories generated from randomly sampled initial conditions are shown. It is seen that even when the area of the object is not known, the uncertainty in mass can be lowered from an initial value of 800?kg to the range 500–700?kg for 72% of the samples, 200–500?kg for 13% of the samples, and 0–200?kg for 15% of the samples. It is further shown that although the uncertainties are large, the actual errors in mass are much lower, with the error RMS being less than 100?kg for 30% of the samples, between 100 and 200?kg for another 30%, and between 200 and 300?kg for 24% of the samples.     

雷达中频信号数据录取与回放系统研制可行性分析

主要对雷达中频信号数据录取和回放分系统研制可行性进行了分析,把系统分为录取和回放两部分,对初步实现方案和工程可行性进行了论证。     

卫星载荷1553B总线数据接口的设计与实现CSCD

卫星载荷总线数据流接口的实现对于卫星载荷数据流的传输体制能否正常工作起着关键性的作用,设计合理的数据流管理方案对于卫星载荷之间的正常通信至关重要。MIL-STD-1553B总线数据传输速率高,实时性好,具有合理的差错控制措施和特有的方式命令,适合星上大数据量的传输任务和特定环境的需求。本文使用龙芯配置卫星载荷1553B总线的工作模式,合理设计载荷数据流的传输形式,实现卫星载荷1553B总线的数据流接口。测试结果表明,数据接口可靠性高,实际应用效果好,满足卫星上的通信设计要求。     

Variable slip window technology in transition detection on pitching airfoil

In the pitching motion, the unsteady transition and relaminarization position plays an important role in the dynamic characteristics of the airfoil. In order to facilitate the computer to automatically and accurately calculate the position of the transition and relaminarization, a Variable Slip Window Technology (VSWT) suitable for airfoil dynamic data processing was developed using the S809 airfoil experimental data in this paper and two calculation strategies, i.e., global strategy and single point strategy, were proposed: global strategy and single point strategy. The core of the VSWT is the selection of the window function h and the parameters setting in the h function. The effect of the VSWT was evaluated using the dimensionless pulse strength value (INB), which can be used to evaluate the signal characteristics, of the root mean square (RMS) value of the fluctuating pressure. It is found that: the h function characteristics have a significant influence on the VSWT. The suitable functions are H_n function constructed in this paper and step function. For the left boundary of the magnified area, the step function can obtain the largest INB value, but the robustness is not good. The H₁ function (Gaussian-like function, n = 1) can show higher robustness while ensuring a large INB value. The two computing strategies, which are single point strategy and global strategy, have their own advantages and disadvantages. The former strategy, that is the single point strategy, can achieve a higher INB value, but the RMS magnification at the feature position needs to be known in advance. Although the INB value obtained by the latter strategy, that is the global strategy, is slightly smaller than the calculation results of the former strategy, it is not necessary to know the RMS magnification at the feature position in advance. So the global strategy has better robustness. The experimental data of NACA0012 airfoil was used to further validate the developed VSWT in this paper, and the results show that the VSWT developed in this paper can still double the INB value of the transition/relaminarization position. The VSWT developed in this paper has certain practicability, which is convenient for the computer to automatically determine the transition/relaminarization characteristics.     

Analysis of laser ranges and angular measurements data fusion for space debris orbit determination

In the framework of space debris, the orbit determination process is a fundamental step, both, for researchers and for satellite operators. The accurate knowledge of the orbit of space debris objects is needed to allow space debris characterization studies and to avoid unnecessary collision avoidance maneuvers.The accuracy of the results of an orbit determination process depends on several factors as the number, the accuracy, the kind of processed measurements, their distribution along the orbit, and the object-observer relative geometry. When the observation coverage of the target orbit is not homogeneous, the accuracy of the orbit determination can be improved processing different kind of observables. Recent studies showed that the satellite laser ranging technique can be successfully applied to space debris.In this paper, we will investigate the benefits of using laser ranges and angular measurements for the orbit determination process. We will analyze the influence of the number of used observations, of the covered arc of orbit, of each observable, and of the observation geometry on the estimated parameters. Finally, using data acquired on short observation arcs, we analyze the achievable accuracies for the orbital regimes with the highest space debris density, and to the consequences of the data fusion on catalog maintenance operations. The results shown are obtained using only real data (both angular and laser measurements) provided by sensors of the Swiss Optical Ground Station and Geodynamics Observatory Zimmerwald owned by the Astronomical Institute of the University of Bern (AIUB) and for some studies also using ranges provided from other stations of the International Laser Ranging Service (ILRS).     

星载原子钟数据预处理的方法研究CSCD

星载原子钟的数据预处理是进行原子钟性能分析和钟差预报的前提,本文主要利用相位数据和频率数据的转换和异常数据的分析处理方法对原子钟数据进行了预处理,有效的保证了数据的可靠性。     

某型无人机数据通信系统设计与实现CSCD

为了实现无人机系统的飞行操纵和机载任务设备控制,设计了数据通信系统。介绍了系统基本工作原理和主要功能组成,并对数据通信系统的功能要求和技术指标进行了分析,按照基本功能单元,对系统软硬件进行了模块化、组合化设计。飞行试验表明该设计达到了系统技术指标要求,满足系统对数据通信系统的功能性要求。     

IP over CCSDS/AOS空间通信QoS保证方法

首先分析空间通信体系发展趋势,提出基于IP over CCSDS/AOS的空间通信模型。在分析总结了地面网QoS(服务质量)机制和AOS(高级在轨系统)虚拟信道调度机制的基础上,提出一种IP(互联网协议)网络层区分服务与数据链路层AOS虚拟信道动态调度相结合的QoS保证方法。该方法将网络层的业务等级划分映射到AOS的虚拟信道分配算法中,并在此基础上实现AOS虚拟信道的动态调度,提高包括话音、视频在内的综合业务在空间链路传输的性能。     

同时传输遥测和伪码测距信号的GMSK技术

介绍了一种同时传输遥测和伪码测距信号的GMSK(高斯最小偏移键控)技术,分析了其调制及解调原理,推导了相关调制、解调及频谱公式,并与UQPSK(非平衡四相相移键控)体制进行了比较。通过对其频谱及误码性能的仿真分析得出,在非线性信道和高码速率下,基于GMSK体制的遥测和伪码测距系统比基于UQPSK体制的系统在包络恒定和频谱利用率方面具有明显优势。