激光陀螺捷联惯导系统的圆锥运动误差激励方法研究

捷联惯导系统的精度受到自身各种误差因素的影响,针对陀螺的标度因数误差和非正交安装角误差,提出了一种以圆锥运动激发姿态误差来进行快速标定的方法.通过理论分析得出,在短时间内,由于标度因数误差和非正交安装角误差的存在,圆锥运动将激发出随时间线性增大的姿态解算误差.将解算得到的姿态误差与陀螺数据联立,可以反解得到标度因数误差和非正交安装角的值.通过仿真验证,安装角误差能达到1"以内,标度因数误差能达到5 ppm以内.     

液晶光谱偏振系统选偏器方位误差研究

为了分析液晶光谱偏振系统的方位误差并降低测量误差,提出了选偏器方位误差的分析方法。该方法基于Stokes矢量及Mueller矩阵,将偏振角的方位误差转化为Stokes矢量传递误差,推导了误差的协方差矩阵,分析了权重系数与延迟相位的变化关系,并对不同偏振态入射光条件下的品质因数变化进行了计算仿真。方位误差依赖于入射光Stokes参数与延迟相位,不同偏振态的入射光品质因数随延迟相位成抛物线变化。当延迟相位位于[60°,120°]区间内,选偏器的方位误差较小,测量误差较小适宜测量。通过对液晶偏振光谱系统配准误差的研究,获得误差来源,为进一步提高系统测量精度奠定了理论基础。     

阵列天线通道误差对波束性能的影响分析

针对阵列天线通道间的误差影响波束性能的问题,分析了通道间误差的来源,并通过波束形成原理说明了通道间误差如何对波束性能造成影响。给出了幅度误差和相位误差多种组合场景作用下波束方向图的仿真结果,并分析了通道误差对波束宽度、旁瓣电平和增益等主要指标的影响。给出了波束形成过程中对通道误差控制范围的建议。     

Optimal codes for correcting single errors and detecting adjacenterrors

Optimal codes that correct single errors and detect double errors within nibbles of power of two length are presented. For each n, a code of length n with the largest possible dimension which corrects single errors and detects double adjacent errors is presented. The problem of constructing optimal codes which correct single errors and detect double adjacent errors within nibbles of length l is discussed     

随机误差对模块化阵列天线副瓣的影响

推导了相位误差、单元位置误差和子阵位置误差的取值范围与模块化阵列天线副瓣累积概率的关系,以及单元位置误差、子阵位置误差与整体位置误差的关系.通过实例说明,激励幅相误差、单元位置误差和子阵位置误差,对实现超低副瓣都是至关重要的.     

大规模MIMO时分双工系统的基站天线互易校准算法

对于采用大规模MIMO技术的时分双工系统,基站天线的互易误差会破坏上下行基带信道互易特性,大幅降低系统下行传输性能。考虑到大规模MIMO技术所带来的基站天线间的耦合效应,该文设计了基于总体最小二乘估计的基站天线互易校准算法,以实现对基站的天线互易误差的补偿。该算法以增加计算复杂度为代价,以及通过增加信道测量样本,克服了上下行信道估计误差对现有天线互易误差校准算法的影响。同时,该文通过瑞利商迭代求解降低了该算法的复杂度。若忽略用户天线互易误差,计算机仿真结果表明,该算法相对于现有的基站天线互易误差校正算法,具有1.8 dB左右的性能增益。若考虑用户天线互易误差,该算法相对于已有的算法,具有随信道估计误差方差减小而增大的增益。     

随机误差对环形阵的旁瓣之影响

分析了随机误差（非统计独立的）对环形阵旁瓣之影响。分别考虑了振幅误差和相位误差两种情形。证明了随机误差可引起旁瓣电平的升高。对于独立的随机误差之情形，还可得到简单的公式。     

MTPT 方法估计机载SAR 残余运动的两个影响因素

由于导航系统测量精度的限制,载机的位置经常存在厘米级的误差,该误差称为残余运动误差。对于机载超高分辨SAR 系统或机载重轨干涉SAR,必须估计并补偿该残余运动误差。MTPT 方法可以估计单幅SAR 图像中的残余运动误差,但是速度和斜距的误差会影响该方法的精度。该文在详细分析速度和斜距误差对MTPT 方法进行残余运动估计的影响的基础上,利用仿真和实测SAR 数据验证了这一点。同时还指出,MTPT 方法虽然可以估计速度和斜距误差,但是它们的精度敏感于相位测量误差;在利用MTPT 方法进行估计之前必须先利用其它更为准确的方法消除平台的速度误差和目标的斜距误差。      

Monte Carlo法在平板裂缝天线辐射缝导纳误差分析中的应用

采用MonteCarlo法分析了平板裂缝天线辐射缝的导纳误差。建立辐射缝导纳误差的概率模型,将波导和裂缝的结构参数误差看作在某误差范围内服从正态分布的随机变量。对这些变量进行抽样计算,得到各个结构参数误差对谐振频率和谐振电导的影响,其中缝隙长度和偏置的误差对谐振电导和谐振频率的影响较大,波导窄边和壁厚误差产生的影响较小。根据计算结果调整各结构参数的误差范围,使它们对谐振频率和谐振电导的影响程度接近,在此基础上分析了同时存在这些误差项时对谐振频率和谐振电导的影响,由此提出满足导纳提取精度要求的加工误差指标。最后用Ansoft HFSS软件仿真验证了该方法的正确性。     

有效值高精度测量量化误差估计与数值模拟

针对电力系统有效值测量存在的不同步误差及量化误差问题,分析了卷积窗加权算法克服不同步误差的优势,推导出基于加权算法下量化相对误差关于采样频率和量化位数的解析式,最后对结论进行数值模拟加以证明。     

Towards Analyzing and Synthesizing Protocols

The production of error-free protocols or complex process interactions is essential to reliable communications. This paper presents techniques for both the detection of errors in protocols and for prevention of errors in their design. The methods have been used successfully to detect and correct errors in existing protocols. A technique based on a reachability analysis is described which detects errors m a design. This "perturbation technique" has been implemented and has successfully detected inconsistencies or errors in existing protocol designs including both X.21 and X.25. The types of errors handled are state deadlocks, unspecified receptions, nonexecutable interactions, and state smbiguities. These errors are discussed and their effects considered. An interactive design technique is then described that prevents design errors. The technique is based on a set of production rules which guarantee that complete reception capability is provided in the interacting processes. These rules have been implemented in the form of a tracking algorithm that prevents a designer from creating unspecified receptions and nonexecutable interactions and monitors for the presence of state deadlocks and ambiguities.     

Computation of the average power pattern of a reflector antennawith random surface errors and misalignment errors

To specify manufacturing tolerances of a reflector antenna, various errors such as random surface errors and misalignment errors must be considered at one time because superposition of the effects of those errors may not hold. Based on the Rahmat-Samii's formulation (1983), a method for computing efficiently the average power pattern of a reflector antenna with those errors is presented. Simulation results show that superposition of the effects of errors does not generally hold and demonstrate how those errors degrade the peak-gain and sidelobe levels     

An error-correcting system for mobile radio data transmission

An error-correcting system for mobile radio data transmission with improved reliability and simple implementation is presented here. The new rate one-half code absolutely corrects two errors within 12 consecutive bits, while the (15, 7, 2) Bose-Chaudhuri-Hocquenquem (BCH) code corrects two errors within 15 bits and Hagelbarger's code corrects two errors within 14 bits. Error propagation in the feedback majority logic decoder is discussed, and it is proved empirically that the new code does not propagate infinite errors. In order to correct burst errors, a 12-column interleaving is proposed for fading channels.     

工艺公差对聚合物竖直耦合型微环谐振器性能的影响

本文根据波导耦合模理论,分析了工艺公差对聚合物竖直耦合型微环谐振器性能的影响。分析结果表明,工艺公差将引起谐振器传输光谱的漂移和光谱形状的改变。为了实现谐振器正常的滤波功能,我们对微环谐振器工艺公差的累积和补偿效应进行了讨论。     

基于UKF地面雷达网的时空配准方法

为消除地面雷达的系统误差和时间误差,提出了基于Unscented卡尔曼滤波(UKF)的三维空间地面雷达网的时空配准方法。该方法将系统误差、时间误差与目标运动模型组合在一个动态模型中,并用UKF方法进行估计。Monte-Carlo仿真表明:该方法能同时有效地估计雷达的系统误差、时间误差,同时得到目标航迹。     

表面误差对双弯曲反射面天线副瓣的影响

天线反射面的表面误差会引起反射面天线的副瓣发生变化。为确定赋形波束双弯曲反射面天线反射面的表面误差与反射面天线副瓣最大值变化之间的关系,采用数理统计的方法,对受到随机表面误差影响的面电流积分,得到天线辐射场。随机表面误差用相关半径和Z向随机误差两个参量表示。根据随机表面误差求出其天线最大副瓣样本分布函数,较好地展现了表面误差引起的副瓣最大值变化,使得反射面天线表面误差引起的副瓣变化可预测,为天线反射面加工的精度要求提供了理论依据。     

观测站存在位置误差条件下基于MDS的多站时差定位算法

为了降低无源定位中观测站站址误差对定位精度产生的不良影响,论文提出了一种基于多维尺度分析的多站无源时差定位解析算法。算法建立了存在站址误差时关于目标位置的线性方程组,推导了方程误差与时差测量误差和站址误差之间的关系式,将误差的统计特性融入到新的加权矩阵之中,使用加权最小二乘方法对目标位置进行了求解。仿真实验表明,算法对于小测量误差具有无偏性,其定位精度能够达到克拉美罗下界,相对于Ho K C的解析算法具有更好的稳健性。      

Performance of ARQ protocols in nonindependent channel errors

The performance of automatic-repeat-request (ARQ) protocols which are affected by nonindependent channel errors is studied. The protocols are the three basic ARQ protocols: stop-and-wait, go-back-N, and selective-repeat. Two types of nonindependent channel errors are considered: the kth-order Markovian errors and the gap errors. Both throughput efficiency and packet delay are obtained. The validity of analysis is verified by computer simulations. One key discovery is that when channel errors are dependent, selective-repeat ARQ achieves the same throughput efficiency as that in independent channel errors     

Diagnosis and correction of multiple logic design errors in digitalcircuits

This paper presents a technique to correct multiple logic design errors in a gate-level netlist. A number of methods have been proposed for correcting single logic design errors. However, the extension of these methods to more than one error is still very limited. We direct our attention to circuits with a low multiplicity of errors. By assuming different error dependency scenarios, multiple errors are corrected by repeatedly applying a single error search and correction algorithm. Experimental results on correcting double-design errors and triple-design errors on ISCAS and MCNC benchmark circuits are included     

Behaviour of power-factor meters under non-sinusoidal current and voltage

Different types of analogue and digital power-factor meters used for low frequencies are studied. Their errors are calculated when the current or voltage waveform is distorted. It is shown that large errors appear under these working conditions. A new measuring instrument is proposed. It has very small errors, even under highly distorted waveforms, having low-pass filters at the inputs to prevent errors generated by high frequency harmonics.