Mission Analysis and Planning System for Korea Multipurpose Satellite-I

The Mission Analysis and Planning System (MAPS) has been developed for a low earth orbiting remote sensing satellite, Korea Multipurpose Satellite-I (KOMPSAT-I), to monitor and control the orbit and the attitude as well as to generate mission timelines and command plans. The MAPS has been designed using a top-down approach and modular programming method to ensure flexibility in modification and expansion of the system. Furthermore, a graphical user interface has been adopted to ensure user friendliness. Design, implementation, and testing of the KOMPSAT MAPS is discussed in this paper.     

INSAT-I --A Multipurpose Domestic Satellite System for India

The Indian National Satellite System-INSAT-I, currently under implementation for operationalisation during 1981, is a multipurpose satellite system for domestic telecommunications and meteorology with capability for nation-wide direct-Tv broadcasting to the rural communities of India. The space-segment of the system will initially comprise of two multi-purpose satellites in geo-stationary orbit, each of which combine capabilities for long-distance telephony, data and TV transmissions, continuous meteorological earth observations in the Visible and Infra Red bands, relay of meteorological data from unattended data relay platforms, disaster warning, radio programme distribution, and direct TV broadcasting to community TV sets. The ground-segment is also designed to be multipurpose in part. INSAT-I thus represents a unique, cost-effective concept. This paper presents an overview of the system.     

Polarization‐Diversity Cross‐Shaped Patch Antenna for Satellite‐DMB Systems

A small reconfigurable patch antenna is proposed to achieve polarization diversity for digital multimedia broadcasting systems at 2.6 GHz. To obtain polarization diversity, a pair of on‐slit PIN diodes is inserted in each diagonal of a cross‐shaped patch. Thus, four PIN‐diodes on these slits are utilized to change the connection of the slits and thus achieve polarization. Bias circuits for the diodes are allocated in the cutting corner of the cross‐shaped patch to minimize the antenna size. The antenna produces left‐hand circular polarization, right‐hand circular polarization, or linear polarization, depending on the PIN‐diode status. Analysis of circular polarization operation is explicated. Measurements show a gain of about 1.5 dB, a cross polarization of about ?20 dB, and an axial ratio of about 2.5 dB.     

Satellite‐based vessel Automatic Identification System: A feasibility and performance analysis

The Automatic Identification System (AIS) is a VHF communication system that provides identification/location information to vessels and shore stations by exchanging data such as position, identification, course, speed, etc. Recently, the interest in detecting and tracking ships at distances from coastlines larger than what can be accomplished by normal terrestrial VHF communications has grown, driven by requirements of long‐range applications such as better handling of hazardous cargo, improved security and countering illegal operations. This paper presents an extension of AIS to a long‐range positioning reporting through a constellation of LEO satellites. It outlines technical challenges like the high rate of message collisions from ships in the field of view of a satellite. Technical solutions are proposed at system and sub‐system level to address these challenges. A computer‐based system simulator is used to assess the system performance and carry out a high‐level system sizing. Results show that a relatively small constellation of LEO satellites can guarantee good ship position detection probability as well as a reporting time interval of a few hours. System performance aspects to be addressed in future work are the possible impact of terrestrial mobile communications interference as well as variations of the estimated traffic data. Copyright © 2009 John Wiley & Sons, Ltd.     

基于LabVIEW的航空装备通用测试系统设计

针对航空装备三级修理工作中难度大的情况,提出了基于实验室虚拟仪器工作平台(LabVIEW)的航空装备通用测试系统的设计方法。根据三级维修的特点,确立了先进行LRU的检测继而进行PCB检测的测试方案,并给出了测试系统硬件设计和软件设计的设计思路。系统对加快维修速度、降低维修费用、提高装备完好率具有十分重要的意义。     

卫星星载操作系统总体设计

文章介绍了我们研制的卫星操作系统的总体设计,是基于消息驱动实时多处理机操作系统,具有冗余容错、重组重构、代码紧凑等特点.     

A Dynamic Bandwidth Allocation Scheme for a Multi‐spot‐beam Satellite System

A multi‐spot‐beam satellite is an attractive technique for future satellite communications since it can support high data rates by projecting high power density to each spot beam and can reuse a frequency in different cells to increase the total system capacity. In this letter, we propose a resource management technique adjusting the bandwidth of each beam to minimize the difference between the traffic demand and allocated capacity. This represents a reasonable solution for dynamic bandwidth allocation, considering a trade‐off between the maximum total capacity and fairness among the spot beams with different traffic demands.     

卫星上行功放监测控制系统的开发

上行功放作为卫星地球站的核心设备，关系到整个卫星传输系统的安全。因此，在平时的值班中需要对其进行实时监测，并以此来判断主、备用功放的完好性。另外，由于整个卫星传输系统受外界影响很大，需要根据情况不断调整卫星上行输出功率。能够随时控制卫星上行功放的工作便显得尤为重要。由于我台卫星地面站所使用的上行功放只     

电视台卫星接收系统的运行维护

广东广播电视台卫星接收系统的信号提供给总控、省网络公司和IPTV播控平台.卫星传输作为台外信号的主要来源,发挥着极其重要的作用.本文先介绍本台卫星接收系统,再从实际工作出发总结天线维护方面的经验以及系统应急预案及处理,最后阐述卫星接收系统的升级改造计划.     

卫星车通话系统改造和技术开发

江苏省广播电视总台（SBC）于2001年7月设计组装了第一个数字卫星新闻采集系统,采用奔驰416车体,含三个讯道电子现场节目制作（EFP）系统,服务于总台江苏新时空、南京零距离等重点新闻栏目的现场报道.正是由于卫星车新闻报道极高的时效性和良好的互动性,总台电视新闻中心和城市频道专门成立卫星连线报道组.电视技术中心也本着提高卫星车现场直播互动性方面的要求,做了大量相关研究和技术开发,对原有简易通话系统进行了全面改造,取得了不错的应用效果.本文将就通话系统改造及相关的技术开发进行详细介绍.     

安装、调试卫星接收系统应注意的问题

卫星电视接收系统主要由卫星天线、卫星接收机等组成。笔者根据多年工作实践 ,就卫星天线的安装、调试问题谈几点体会。(1)高频头与卫星接收机之间连接的同轴电缆线应采用高质量的 75 - 5电缆 ,以保证卫星信号的传输质量。在做Ｆ头时 ,插入Ｆ头的一截轴心线露出长度应适当 ,过短可能使高频头与卫星接收机接触不良 ,过长可能触及高频头或卫星接收机内部的其他元件而产生故障 ,一般情况下 ,Ｆ头轴芯线露出 4～ 5ｍｍ比较合适。特别应注意的是 ,高频头输出端的螺纹是英制的 ,Ｆ头也应与之相适配 ,以保证电缆线与高频头牢固连接。(2 )调整卫星接…     

GPS‐Based Orbit Determination for KOMPSAT‐5 Satellite

Korea Multi‐Purpose Satellite‐5 (KOMPSAT‐5) is the first satellite in Korea that provides 1 m resolution synthetic aperture radar (SAR) images. Precise orbit determination (POD) using a dual‐frequency IGOR receiver data is performed to conduct high‐resolution SAR images. We suggest orbit determination strategies based on a differential GPS technique. Double‐differenced phase observations are sampled every 30 seconds. A dynamic model approach using an estimation of general empirical acceleration every 6 minutes through a batch least‐squares estimator is applied. The orbit accuracy is validated using real data from GRACE and KOMPSAT‐2 as well as simulated KOMPSAT‐5 data. The POD results using GRACE satellite are adjusted through satellite laser ranging data and compared with publicly available reference orbit data. Operational orbit determination satisfies 5 m root sum square (RSS) in one sigma, and POD meets the orbit accuracy requirements of less than 20 cm and 0.003 cm/s RSS in position and velocity, respectively.     

Interference‐Limited Dynamic Resource Management for an Integrated Satellite/Terrestrial System

An integrated multi‐beam satellite and multi‐cell terrestrial system is an attractive means for highly efficient communication due to the fact that the two components (satellite and terrestrial) make the most of each other's resources. In this paper, a terrestrial component reuses a satellite's resources under the control of the satellite's network management system. This allows the resource allocation for the satellite and terrestrial components to be coordinated to optimize spectral efficiency and increase overall system capacity. In such a system, the satellite resources reused in the terrestrial component may bring about severe interference, which is one of the main factors affecting system capacity. Under this consideration, the objective of this paper is to achieve an optimized resource allocation in both components in such a way as to minimize any resulting inter‐component interference. The objective of the proposed scheme is to mitigate this inter‐component interference by optimizing the total transmission power — the result of which can lead to an increase in capacity. The simulation results in this paper illustrate that the proposed scheme affords a more energy‐efficient system to be implemented, compared to a conventional power management scheme, by allocating the bandwidth uniformly regardless of the amount of interference or traffic demand.     

Physicochemically Stable Polymer‐Coupled Oxide Dielectrics for Multipurpose Organic Electronic Applications

A chemically coupled polymer layer is introduced onto inorganic oxide dielectrics from a dilute chlorosilane‐terminated polystyrene (PS) solution. As a result of this surface modification, hydrophilic‐oxide dielectrics gain hydrophobic, physicochemically stable properties. On such PS‐coupled SiO₂ or AlO_x dielectrics, various vacuum‐ and solution‐processable organic semiconductors can develop highly ordered crystalline structures that provide higher field‐effect mobilities (μ_FETs) than other surface‐modified systems, and negligible hysteresis in organic field‐effect transistors (OFETs). In particular, the use of PS‐coupled AlO_x nanodielectrics enables a solution‐processable triethylsilylethynyl anthradithiophene OFET to operate with μ_FET ～ 1.26 cm² V^?1 s^?1 at a gate voltage below –1 V. In addition, a complementary metal‐oxide semiconductor‐like organic inverter with a high voltage gain of approximately 32 was successfully fabricated on a PS‐coupled SiO₂ dielectric.     

某测试设备故障监测系统的设计

以某型测试设备为研究对象,钟对该设备的电路结构和工作特点,设计了该测试设备故障监测系统.系统的开发基于嵌入式PC104计算机系统及其系列功能模块,针对被测设备故障信息的特点,分别设计了开关量、电压量、时间量、频率量信号调理模块;设计中综合运用了光电隔离、多路信号采样复用、高精度定时、测频、计数等技术,实现了监测诊断系统微负载动态接入和对被测设备全程在线隔离测试.     

某测试设备故障监测系统的设计

以某型测试设备为研究对象,针对该设备的电路结构和工作特点,设计了该测试设备故障监测系统。系统的开发基于嵌入式PC104计算机系统及其系列功能模块,针对被测设备故障信息的特点,分别设计了开关量、电压量、时间量、频率量信号调理模块;设计中综合运用了光电隔离、多路信号采样复用、高精度定时、测频、计数等技术,实现了监测诊断系统微负载动态接入和对被测设备全程在线隔离测试。     

BC3192测试系统的开发及使用说明

基于微机的强大功能以及VXI总线开放灵活的特点，介绍BC3192测试系统的研制开发，同时给出其使用说明。     

北斗卫星导航系统发展现状与建设构想

北斗卫星导航系统当前处于从区域服务到全球服务承上启下的关键时期。简要回顾了北斗系统发展历程,系统地总结了北斗区域系统发展情况与技术特点,针对正在进行中的北斗全球系统建设任务,深入分析了目前面临的难点问题,探讨了北斗全球系统基本导航、定位报告和星基增强的整体服务规划构想,提出了对北斗全球系统总体设计的几点建议。     

全球星卫星移动通信系统及其发展现状

简述第三代移动通信和卫星移动通信关系和全球星卫星移动通信系统的特征。介绍全球星卫星移动通信系统的近期发展和应用前景     

A Satellite Radio Interface for IMT‐2000

This paper presents a new satellite radio interface, satellite code division multiple access (SAT‐CDMA), for the satellite component of IMT‐2000. The SAT‐CDMA was proposed by Korea and was based on wideband CDMA (WCDMA) for a high degree of commonality with the terrestrial component of IMT‐2000. Because a satellite link has a longer round trip delay and a higher Doppler shift than a terrestrial link, we developed new technologies that would make the satellite component especially efficient. We present the main features of the SAT‐CDMA radio interface by focusing on satellite‐specific schemes. We also demonstrate with extensive comparison results the performance of the main technologies in the SAT‐CDMA radio interface.