Tracking and data acquisition for space exploration

The tracking and data acquisition systems provide the key link between the remote spacecraft and the scientific experimenter on the ground. The operation of the space experiment takes place through the links of command, telemetry and tracking. The evolution from the early very simple spacecraft missions toward more complex and sophisticated missions has been paralleled by a similar evolution in the tracking and data acquisition systems. The early Minitrack interferometer tracking system still carries the major tracking workload for space missions; however greater tracking accuracy requirements for more recent missions, such as the Orbiting Geophysical Observatory and the Apollo mission, have brought about the development of unified tracking and data acquisition systems which utilize hybrid pseudo-random code/sidetone ranging techniques. The data acquisition has evolved from analog telemetry systems to the present day heavy use of PCM digital telemetry. Likewise the command systems have evolved from early simple on/off command systems into PCM digital command data systems. The trend is toward greater real time control of more complex functions on board the spacecraft. Newer spacecraft are incorporating computer-type systems in the spacecraft which require programming and memory load through the ground command link. The most attractive concept for the next generation network for tracking and data acquisition is a network consisting of synchronous-orbit Tracking and Data Relay Satellites for covering launches and low-orbit earth satellites plus a few selected ground stations for supporting spacecraft in high earth orbit and lunar orbit.     

无人机系统的卫星中继数据链

针对大中型无人机系统实现远程测控与信息传输的技术需求,在参考国外＂捕食者＂、＂全球鹰＂等先进无人机系统技术体制和实现方案的基础上,提出了利用商业或军用通信卫星作为空中中继平台,建立无人机卫星中继数据链,实现我国远程无人机系统的超视距遥控、遥测和侦察信息实时传输的解决方案,这对延伸无人机系统的作用距离、提高作战效能具有重要意义。文中分析了无人机系统卫星中继数据链的技术体制,提出了工程应用中的关键技术,对具体的工程实现具有一定的指导意义。     

The 1553 Advanced Communication Engine (1553-ACE)

The next-generation 1553 terminals will address the concerns of reducing the size, power, and cost and adding features required to off-load the system designer. The 1553-ACE series programmable terminal and the BUS-61580 ACE terminal are described. The various features incorporated especially the programmable options which make this series terminal so flexible are discussed. The ACE series has an advanced set of registers, internal 4 K words of shared RAM, dual encoder/decoders, and three-state buffers for address and data I/Os in one monolithic. It has selective I/O features, such as buffered DMA, or a shared RAM interface, with or without zero wait states to support a variety of microprocessors. Additional programmable features incorporated are RT circular data stacks programmed by individual subaddress, internal RAM command illegalization, and advanced bus controller and bus monitor options for bus snooping or for selective monitoring. The electrical, mechanical, and special competitive features of the 1553 ACE-series are highlighted. The military screening and mechanical specifications and other product options are covered     

测控应答机下行调制度问题的技术分析

针对应答机采用不同的接收信号功率控制方式，对下行测距调制度、残留遥控调制度以及转发噪声调制度的情况进行了理论分析，得到了各种情况下的调制度数学模型，可供读者在航天工程的测控链路设计及应答机设计时参考。     

弹地人在回路末制导时延补偿改进模型

基于弹地通信链路的人在回路制导导弹利用惯性导航系统短时导航精度高的特点,对导弹末制导中导引指令的时间延迟提出了两种补偿模型及改进方法。通过Simulink仿真,得出距离和导引量与目标横向误差的关系及其方法改进后精度的提高幅度,并进行了分析。仿真结果验证了该方法的有效性。     

Countermeasures of command and control (C2) capabilities in a hostile environment

For a military airborne platform to survive in a hostile battlefield environment, the rapid detection and geo-location of an enemy (or terrorist) gunner is highly desirable. One approach is to develop an electronic countermeasure system against the gunner's command and communication (C2) capabilities, specifically the usage of modern wireless phones. Such a countermeasure system conducts a quick detection and geo-location of the targeted (hostile) mobile wireless subscriber, allows the airborne platform to make appropriate decisions: 1) to divert and avoid potential military conflicts; 2) to cue artillery supports and prepare for attack; or 3) to relay the coordinates of the potential threat to his own command and control units. In this paper, we discuss the technical approach of the countermeasure system, especially in two design areas: 1) detection and tracking of enemy C2 signals; and 2) geo-location of a targeted communication link.     

Control and stabilization of nonlinear uncertain elastic roboticarm

An approach is presented to the control of an uncertain nonlinear flexible robot arm (PUMA-type) with three rotational joints. The third link is assumed to be elastic. A torquer control law, which is a function of the trajectory error, is derived for controlling the joint angles. The knowledge of the system dynamics is not required for the derivation of the controller. This controller includes a reference model to generate command joint angle trajectories, and a dynamic system in the feedback path which requires only joint angle and rate for feedback. The torquer controller asymptotically decouples the elastic dynamics into two subsystems, representing the transverse vibration of the elastic link in two orthogonal planes. For the damping of the elastic vibration, a force control law using modal velocity feedback is synthesized. Simulation results are presented to show that the combination of the torque and force control law accomplishes reference joint angle trajectory tracking and elastic mode stabilization despite the uncertainty in the system     

绝对式恒光源24位光电轴角编码器在光电经纬仪上的应用

为满足某型光电经纬仪的使用要求,设计了某绝对式恒光源 24位光电轴角编码器分系统。该编码器采用 16位绝对式光学码盘,码盘刻划有粗码道、通圈码道、中精码道和精码道。精码道的线对数为 16 384(14位)。方位和高低编码器的处理电路设计在一块电路板上,采用一片 DSP为主机,6个读数头输出 64路码盘光电信号分别经放大整形、A/D转换输入至 DSP。DSP完成数据采集、细分、译码、校正等处理,把轴的转角变换成 24位自然二进制角度代码输出和上传。使用情况表明:该编码器的光机结构布局合理、性能稳定,电路板和元器件少、操作简单、测角精度高,满足某型光电经纬仪对于编码器系统的要求,具有较高的实用价值。     

临近空间飞行器测控与信息传输系统频段选择

 临近空间飞行器是高性能信息化武器平台,测控（TT&;C）与信息传输系统是其信息保障的核心,而选择合理、可行的频段是展开系统设计的前提和基础。频段选择影响到整个技术方案的制定,是一个需综合考虑、影响深远并具有战略意义的关键问题,从国际电联（ITU）国际标准、高速数传、接收信噪比（SNR）、“三抗”、超视距中继、黑障、雨衰以及设备研制成熟度8个方面全面、细致论证了近空间平台测控系统的频段选择问题,最终得出在视距链路中以Ka频段为宜,在超视距链路中以Ku/Ka双频段为宜的结论。     

飞机操纵系统优化设计软件开发与运动仿真

飞机发动机操纵系统和舵面操纵系统通常采用连杆机构传递运动。本文介绍了飞机操纵系统的通用优化设计软件———ACSODS软件。本软件可根据传动系统的设计要求,对传动系统的各参数进行优化设计,同时生成系统运动的动态仿真图,因此,可以大大缩短传动系统的设计周期和设计费用。软件操作简便,界面友好,有较好的人机对话式的交互功能,并具有直观形象的设计特点,为设计者提供了一个高效、实用的设计平台。通过与实际系统的比较,设计结果完全能满足系统的要求。     

针对机载应用的H.264编码器评估方法

本文针对机载图像实时压缩的应用需求,讨论了一种H.264编码器性能的评估方法.该方法以典型的机载视频画面为测试序列,对编码器设定一组恒定QP值进行编码,将压缩后码流比特率与标准算法对比,评判编码器性能的优劣.通过对三种不同编码器的测试对比,证明了该评估方法的有效性.     

舰艇编队网络化反导作战指挥体系研究

网络中心作战条件下,传统作战指挥体系已经无法满足作战指挥需要,文章从指挥体制和指挥方式两方面探讨了适应舰艇编队网络中心作战模式的新型指挥体系;基于网络中心作战模式下舰艇编队作战指挥特点,分析了传统指挥体制和指挥方式的不足,提出一种由动态网络型指挥体制和动态分权式指挥方式构成的新指挥体系,并分析了其在指挥可靠性、整体性和时效性方面的优势。     

基于DSP和FPGA的视频编码器协同设计与算法优化实现

采用DSP和FPGA协同技术设计实现了一个高性能的MPEG-4视频编码器。FPGA模块完成视频采集、YUV分离、数据I/O等功能,而使用DSP专一进行视频压缩编码。针对DSP片内资源特点设计了片内存储器数据分配方案,并根据该方案优化了MPEG-4视频压缩的数据流模式。提出了基于宏块空间复杂度的宏块类型判断算法,有效地降低了视频压缩算法的计算复杂度。测试结果表明,采用MPEG-4视频标准该视频编码器每秒能够压缩39.2帧CIF图像。     

快速获得感应同步器细分误差的方法

介绍一种获得感应同步器细分误差的快速数学方法。其优点是:快速、无需其它仪器、直接生成细分误差补偿数据。     

Execute Command in Space Communications

Two types of feedback systems for a command channel are described. a) Complex Feedback?where, for each command, an identification is relayed back over the feedback channel. b) Decision Feedback?where the feedback channel is used only to state whether the satellite recognized the transmission as a command word. For a), the decision as to whether a command was properly received at the satellite is made on the ground, while for b), the decision is made at the satellite, the only purpose of the feedback channel being to cause the ground station to retransmit the command word if the satellite did not recognize the initial transmission. The decision feedback system then amounts to a one-way channel, since the satellite makes a decision after the initial transmission as to whether or not a command word was sent. If the transmitted command word is interpreted as a command, whether correct or not, the ground station has no further control. The following theorem is proved rigorously: ``It is always possible to specify a decision feedback system which gives the same error performance as a given complex feedback system.'     

基于模块级流水和并行处理的CAVLC编码器实现

基于上下文的自适应变长编码(CAVLC)是高清视频压缩标准H.264的关键模块。CAVLC编码器设计的优劣直接影响系统实时性。本文设计的编码器整体采用模块级流水线架构,关键子模块内部采用并行处理,提高了实时性。设计在Xilinx公司的xc5vlx330t芯片上实现,综合后时钟频率可达222MHz。视频数据的实际测试显示,编码器可满足系统实时性需求。     

考虑多边界状态约束的飞翼布局无人机姿态控制

以大展弦比飞翼布局无人机为研究对象,针对强扰动环境下多边界状态约束时的飞行姿态控制问题,提出一种指令-控制律联合限制的全状态约束控制方法。该控制方法分别独立设计了指令边界限制器、过渡指令产生器和指令跟踪控制器3个部分。首先,基于无人机动力学特性设计的指令边界限制器,利用无人机的各个状态边界来限制姿态控制器的指令,实现了将非受控状态的约束问题转化为受控状态的约束问题;其次,基于"安排过渡过程"的思想并考虑约束限制环节,设计了过渡指令产生器,为无人机在线生成从当前姿态到期望跟踪姿态的过渡指令;最后,基于障碍Lyapunov函数和扩张状态观测器,设计了指令跟踪控制器,使无人机能够克服干扰且快速稳定地跟踪过渡指令。通过采用Lyapunov稳定性理论分析,该控制方法能够保证姿态跟踪误差收敛有界,且始终处于给定区间内部。仿真结果表明,该控制方法能够保证无人机飞行状态在不超出约束边界的同时,实现对姿态指令的准确跟踪。     

基于IK121和RESM的转台测角系统设计与应用

分析了光电编码器较圆感应同步器应用在高精度转台测角系统中的优势，并针对传统光电编码器测角系统的诸多限制，结合高精度转台高效率研制和便于安装调试需求，提出一种基于IK121计数卡和RESM编码器的高精度测角系统，并结合某型号转台进行了实物试验，结果表明该测角系统能实现转台高位置精度、高速率精度控制要求，并且安装使用维护方便。     

飞机引导控制指令研究

飞机引导控制指令的选择直接影响到飞行控制性能,对引导控制指令的种类和优劣进行研究具有重要意义。首先,以纵向为例,分析认为可选择的引导控制指令有俯仰角指令、法向过载指令和垂直速率指令;然后,在几个合理假设的基础上,采用理论分析方法对上述三种引导控制指令进行比较,所得结论如下:在抑制风对迎角、高度的干扰,以及抑制参数摄动对高度的干扰等方面,能力由高到低分别为过载指令、垂直速率指令和俯仰角指令。最后,通过仿真对上述结论进行了辅助验证。