JSJ精密水准仪经纬仪综合检验仪原理及误差分析

介绍了一种最新研制的在室内检定高精度水准仪经纬仪的计量标准仪器,并分析了该仪器设计原理及误差来源。     

飞船在大气层外飞行段的主要参数对轨道的影响

飞船返回地球时再入速度很大,过大的过载和气动加热率尤其对载人飞船带来安全性问题。如果利用航天器在大气层外及其边缘处多次再入运动,可降低速度、耗散热量。文章主要分析了载人飞船在大气层外多次再入飞行时的各主要参数对飞船轨道和轨道终点的影响。在分析过程中,首先建立了飞船在大气层外飞行的数学模型,进而通过大量的数值仿真得到一条基准轨道,在此基础上分别改变轨道起始点参数（倾角、偏航角和飞行速度）的初始值,分析轨道的特性及轨道的终点误差。最后根据起始点参数值和对应的轨道终点误差值的关系,得到了飞船在大气层外飞行时的起始参数对飞行轨道及轨道终点影响的敏感度,从而为工程上轨道的设计提供一个有效的参考依据。     

全谐波误差分离技术

全谐波误差分离技术是一种新的误差分离技术。它是在对多步法误差分离技术测量精确度进行理论分析和实验验证的研究基础上提出的。它可以分离开主轴系统误差和工件圆度误差在1～500Hz内的全部谐波误差,进行数字滤波和降低分度指示台分度精度的要求。全谐波误差分离技术可以方便地应用于精密主轴或工件圆度误差的测量,测量精度可由10~(-9)m级提高到10~(-10)m级。     

一种高精度天线转台的实时补偿方法

天线转台是天线罩电性能测试系统的重要组成部分,对精度要求很高.由于磁栅传感器磁栅特性和安装等原因,其精度往往达不到厂家标称精度,需要进行补偿以满足系统要求.本文详细分析了造成磁栅测量精度达不到标称精度的原因,并针对主要原因提出了一种软件实时补偿算法,详细论述了补偿原理,通过测量转台绝对定位精度,验证了该实时补偿算法具有...     

Graph-tree-based software control flow checking for COTS processors on pico-satellites

 This paper proposes a generic high-performance and low-time-overhead software control flow checking solution, graph-tree-based control flow checking (GTCFC) for space-borne commercial- off-the-shelf (COTS) processors. A graph tree data structure with a topology similar to common trees is introduced to transform the control flow graphs of target programs. This together with design of IDs and signatures of its vertices and edges allows for an easy check of legality of actual branching during target program execution. As a result, the algorithm not only is capable of detecting all single and multiple branching errors with low latency and time overheads along with a linear-complexity space overhead, but also remains generic among arbitrary instruction sets and independent of any specific hardware. Tests of the algorithm using a COTS-processor-based onboard computer (OBC) of in-service ZDPS-1A pico-satellite products show that GTCFC can detect over 90% of the randomly injected and all-pattern-covering branching errors for different types of target programs, with performance and overheads consistent with the theoretical analysis; and beats well-established preeminent control flow checking algorithms in these dimensions. Furthermore, it is validated that GTCGC not only can be accommodated in pico-satellites conveniently with still sufficient system margins left, but also has the ability to minimize the risk of control flow errors being undetected in their space missions. Therefore, due to its effectiveness, efficiency, and compatibility, the GTCFC solution is ready for applications on COTS processors on pico-satellites in their real space missions.     

基于FPGA的数据链路误码仪设计

本文对数据链路通信系统中的误码仪进行分析设计,给出了误码率的定义,剖析了误码仪的工作原理,并分别对发射端和接收端两部分进行了描述,介绍了两种典型误码仪的工作方法,其中详细描述了阈值检测法的原理和工作模式。文中实现了发射端和接收端的FPGA设计,给出FPGA设计结论,并最终表述了在数据链路上的应用情况。     

基于希尔伯特-黄变换的雷达数据误差修正处理技术

由于雷达跟踪测量数据总存在误差,而目前采用的误差处理算法修正效果并不理想,为了有效估计数据中的未知误差,提高数据处理的精度,提出了一种基于希尔伯特-黄算法的雷达误差残差诊断方法,利用得到的内蕴模态函数拟合出误差残差的特征,准确分离出设备的误差信息。通过对某雷达的实测数据分析证明该方法较其他方法对解决该类问题更为有效,且在事后高精度数据处理中具有较好的实用性。     

交会椭圆轨道目标Hill制导误差分析

在交会椭圆轨道目标阶段,Hill制导受各种误差因素的影响。介绍了椭圆轨道目标Hill 制导的误差因素,并着重研究了导航误差和控制误差对终端位置的影响,给出了误差的基本 表达式。与交会圆轨道目标情况进行比较,分析了初始真近点角对导航误差引起的终端位置 偏差的影响。在此基础上给出了一种修正算法,理论上证明了修正算法能显著提高终端位置 的精度。通过Monte\|Carlo方法的仿真结果表明,合理改变初始真近点角能减小导航误差引 起的终端位置偏差,并且修正算法能更有效提高制导精度。
     

基于频谱分析判定接收机错锁的方法研究

目前判定接收机错锁仅仅凭借经验,导致目标捕获时间长。本文基于模拟调相信号相干解调输出信号的谱线特征,提出一种新的简单判定接收机错锁的方法。采用该方法方便地实现了频率引导的闭环控制,提高了接收机的自动化程度。     

Accuracy assessment of single and double difference models for the single epoch GPS compass

The single epoch GPS compass is an important field of study, since it is a valuable technique for the orientation estimation of vehicles and it can guarantee a total independence from carrier phase slips in practical applications. To achieve highly accurate angular estimates, the unknown integer ambiguities of the carrier phase observables need to be resolved. Past researches focus on the ambiguity resolution for single epoch; however, accuracy is another significant problem for many challenging applications. In this contribution, the accuracy is evaluated for the non-common clock scheme of the receivers and the common clock scheme of the receivers, respectively. We focus on three scenarios for either scheme: single difference model vs. double difference model, single frequency model vs. multiple frequency model and optimal linear combinations vs. traditional triple-frequency least squares. We deduce the short baseline precision for a number of different available models and analyze the difference in accuracy for those models. Compared with the single or double difference model of the non-common clock scheme, the single difference model of the common clock scheme can greatly reduce the vertical component error of baseline vector, which results in higher elevation accuracy. The least squares estimator can also reduce the error of fixed baseline vector with the aid of the multi-frequency observation, thereby improving the attitude accuracy. In essence, the “accuracy improvement” is attributed to the difference in accuracy for different models, not a real improvement for any specific model. If all noise levels of GPS triple frequency carrier phase are assumed the same in unit of cycles, it can be proved that the optimal linear combination approach is equivalent to the traditional triple-frequency least squares, no matter which scheme is utilized. Both simulations and actual experiments have been performed to verify the correctness of theoretical analysis.