【作者】 杨宇晓；

【导师】 宋茂忠；

【作者基本信息】 南京航空航天大学 ， 通信与信息系统， 2008， 硕士

【摘要】 微小卫星通信系统作为实现星地通信的唯一方式,是卫星最基本、最重要的系统之一,本文首先针对微小卫星体积小、重量轻、功耗低的设计要求和卫星飞行任务对通信系统的功能需求,给出了完整的通信系统设计方案。为满足星上CCD相机拍摄的图像数据下传,和配合地面测控网实现测距、测速功能的需要,本文分别设计了两种通信体制下的帧结构方案:其一是根据国际空间数据系统咨询委员会(CCSDS)标准,设计的通信机体制下的虚拟信道数据单元(VCDU)数据帧结构;其二是根据我国国家军用标准规定,设计的统一S波段应答机体制下的PCM遥测帧结构。[0]为了便于对微小卫星通信子系统进行测试,设计实现了通信链路仿真测试平台,并完成了两部分的软件硬件调试工作。该平台由测试信号源和接收端测试解码器组成,测试信号源用于仿真下行链路数据采编器,对信道和数据传感部分进行测试;测试解码器用于仿真下行链路数据解码器。所设计的测试信号源基于PC104嵌入式计算机平台,利用可定制的A/D扩展板和串口扩展板,实现对传感器数据和图像数据的采集及接收,在软件实现上将两种数据的装帧编码设置为两个任务,只有传感器数据装帧任务不执行时,才进行图像数据的装帧处理,并最终对外输出统一的VCDU数据流。下行链路数据解码器利用DM642开发板的丰富外围接口,完成了下行数据流的串口接收,并在CCS环境下实现对数据的帧同步及解码处理,同时结合TI公司推出的NDK软件开发包配置完成了DSP端的TCP/IP协议栈,实现与计算机间的网络通信。更多还原

【Abstract】 Being the only way to achieve the satellite-earth communication, micro-sattellite communication system is one of the most fundamental and important part of the satellite. This thesis, first of all, has proposed a complete design of communication system, according to the demand of miro-sattellite: small-volume, lightness, and low-power, and satisfied the need the function of communication system for satellite-flying tasks.For satisfying the down-loading of image data shot by CCD camera and achieving the function of distance and velocity measurement cooperating with ground supervision system, this thesis designed two kinds of frame construction affiliated by two types of communication system: the one is Virtual Channel Data Unit (VCDU) data frame construction affiliated by communicating system designed in terms of The Consultative Committee for Space Data Systems (CCSDS); the other is Pulse Code Modulation (PCM) telemeter frame construction affiliated by Unite S Band (USB) transponder system, according to the nation’s military standard.Emulated test platform, consisted of testing singal source and receiver, for testing the communication system of micro-sattellite. Testing singal source is used for emulating the down-link data coder; testing channel and data sensor .Testing decoder is used for emulating the down-link data decoder. Testing data source based on PC104 embedded computer platform, aimed at collecting and receiving the sensor data and image data by using customizable A/D expanded board and serial interface expanded board. In order to assure the real-time sensor data intactly, there are two tasks to framing code for sensor data and image data. During working period, so long as sensor data didn’t executed the framing work, the framing process of image data is advancing and finally unity VCDU data stream is exported. Down-link data decoder, by using the abundant outer interface of DM642, has achieved the receipt of down data steam. Under the circumstances of Code Composer Studio (CCS), we have finished the synchronous frame and decoding process for various types of data. Besides, we have installed TCP/IP on DSP, combining NDK published by TI, for the purpose of network communication.更多还原