Rank detector preprocessor for glint reduction in a tracking radar

A rank detector is used to detect instantaneous received power fades in a tracking radar. On detection of a fade, censorship of the angular position measurement is implemented in a Kalman tracking filter. It is shown that this technique can typically give a 15% angular tracking improvement on highly dynamic targets     

On analytical evaluation of glint error reduction for frequency-hopping radars

Analytical techniques are presented for evaluating the glint error reduction of frequency-agile tracking radars employing discrete frequency-hopping (FH). The techniques can be used to compare the tracking accuracies obtained with different procedures for frequency selection. The cases of random, cyclic, and hybrid FH are worked out in detail. An illustration using a simple alpha-beta tracking filter indicates that the preferred type of frequency selection usually depends on the filter gains used in a specific application.<>     

Feedback median filter for robust preprocessing of glint noise

Glint noise may arise in a target tracking system. The non-Gaussian behavior of glint noise can severely degrade the tracking performance. Measurement preprocessing at the front-end of the tracker is an effective method to reduce glint noise. The preprocessor proposed by Hewer, Martin, and Zeh (1987), which used the computationally intensive M-estimator, may not be suitable for practical implementation. An alternative method employing the median filter is studied here. The median filter is well known for its simplicity and robustness. However, the efficiency of the median filter can be seriously degraded if input samples are not identically distributed. This is what we may encounter in the tracking problem. A feedback median filter is then proposed to overcome this impediment without substantially increasing complexity. Simulations show that the new preprocessor can greatly improve tracking performance in the glint noise environment.     

未来海上空战对舰载战斗机的发展需求

针对未来海上空战的特点,通过美俄两国主要的舰载战斗机的对比分析,提出了几点对未来航母舰载战斗机的发展需求。     

EM Transient Protection Requirements for Avionics LRUs

Avionics and electronic equipment installed in aircraft and air breathing missiles are required to operate without upset or damage when subjected to EM environments caused by lightning, NEMP, and Intrasystems transients. To simplify the design effort required to protect electronic equipment and minimize overlapping transient requirements and qualification tests, unified test requirements and procedures are needed. The goal of these unified test procedures would be to insure a known susceptibility level for each newly designed electronic Line Replaceable Unit (LRU). Ten avionics equipments in current Air Force inventory were tested for the purpose of developing unified procedure test methods. Operating LRUs were subjected to transients using common mode cable current (CMCC), groung potentials and chatteriing relay cable injection methods. Based on observed test results and review of current test requirements, test methods and test levels for unified test procedures for power-on transient tests of avionics equipment have been formulated.     

浅析机载软件工具鉴定要求

随着大量工具应用于机载软件的开发,工具鉴定的问题日益突出。本文介绍了机载软件工具鉴定的原因和目的,并基于机载软件工具的分类介绍了工具鉴定的前提和准则以及工具鉴定的数据要求,最后提出了工具鉴定过程中需要关注和解决的问题。     

国际上教练机的装备需求浅析

空军规模的大小对教练机装备的数量、类型、功能需求各有不同。本文通过对世界部分国家的空中力量、教练机装备以及飞行员训练情况进行梳理,分析不同规模下的空军对教练机的装备需求、发展需要,并从中得出几点发展思考。     

民机材料适航要求与标准化需求

介绍了民机材料适航性要求及国内材料适航方面的差距,分析了航空材料标准现状和民机研制对材料标准化的需求,提出了今后民机材料标准化的工作重点。     

Pointing and Stability Requirements for Earth Orbital Experiments

Experiments for manned and unmanned space facilities of the next decade will impose stringent requirements for accurately pointing and/or maintaining stability of the space platforms over extended periods. Potential experiment programs identified to date in various NASA-and contractor-sponsored studies have been reviewed in order to define critical values and ranges for the following pointing/stability parameters: 1) pointing accuracy, 2) line-of-sight stability, 3) angular rate, and/or 4) acceleration level. The most stringent requirements were found to be in the research categories of: stellar and solar astronomy, earth observations, space physics, communications and navigation, and space biology.     

浅谈飞机复合材料结构的适航审定

随着国际上商用飞机复合材料结构用量的不断增加,复合材料结构适航审定的要求和方法也在日臻完善。本文作者以国际通用的咨询通告AC20-107A为基础,结合对复合材料结构进行适航审定的经验,介绍了针对材料性能、强度、阻燃、制造等方面常用的适航审定方法。     

Observability Requirements for Three-Dimensional Tracking via Angle Measurements

Observability requirements previously established for bearings-only tracking in two dimensions are extended to a class of three-dimensional estimation algorithms capable of processing any pairwise combination of azimuth bearing, conical bearing, and depth/elevation angle measurements. Although these algorithms are intrinsically nonlinear, it is shown that they can be analyzed in a linear framework without sacrificing mathematical rigor. A simplified observability criterion, applicable to both autonomous and nonautonomous linear systems, is presented and utilized to specify conditions on own-ship motion which are both necessary and sufficient for a unique tracking solution. Further analysis reveals that observability dependence on own-ship maneuvers for the three-dimensional algorithms considered here parallels the concomitant two-dimensional requirements. An interesting difference, however, is that under certain conditions, a unique tracking solution can be obtained in three dimensions for unaccelerated own-ship motion.     

Orbital and Attitude Prediction Accuracy Requirements for Satellites

This paper examines the criteria for selecting the orbital and attitude prediction accuracy requirements for communications satellites. The accuracy requirements have been analyzed in terms of the various space operations involved, e.g., satellite acquisition, guidance and control, communications, telemetry, and command. It is hoped that the findings of this investigation will prove useful in satellite mission planning and design, thereby facilitating a judicious choice of the various satellite and ground components of the related subsystems.     

民用运输类飞机的高原适航性分析

高原机场和航线运行的特点 民用运输机的高原机场和航线运营问题,在全球范围内只有少数几个地区会涉及到.这些典型的地区包括:南美、中亚和中国.而中国的青藏高原无疑是所有这些地区中环境最为恶劣的地区.     

智能制造环境下的数控系统发展需求

"智能"是"中国制造2025"的核心要素,数控系统是制造装备实现智能化的关键要素。论文首先提出机床的信息互通和开放式标准数据接口是实现机床智能化的前提,举例说明了STEP-NC在通用数据接口方面的优越性,概述了适用于数控系统的通讯总线特征;在此基础上,介绍了工艺大数据对生产加工的重要性和其对新一代数控系统的要求,针对制造业数据平台的需求,对大数据信息挖掘技术做了相关介绍。依托于以上两点,总结了智能化数控系统可具备的功能,依托于工艺大数据平台,重点分析了智能工艺规划和加工参数自整定的实现方案,以及智能数控对高速高精加工所提供的便利。     

对测量雷达的一些新需求与精细测量技术

新一代测量雷达在发展各种先进武器平台与航空航天及空间技术方面有广泛的应用前景。本文讨论对测量雷达的一些新的需求及相关技术,对雷达精细测量的需求与有关技术是本文讨论重点。     

企业信息编码标准化需求分析途径探析

分析了企业信息编码标准化工作的基本特点,针对制造企业探讨了3种比较典型的编码标准化需求分析途径.对于指导企业全面分析编码需求,构建实用、科学的信息编码标准体系具有重要意义.     

民机产品安全性要求剖析

首先分析了安全性的具体含义,然后通过对已在多种民用飞机上安装的某型自动驾驶仪系统所采用的安全措施的介绍,对民机产品安全性的具体要求进行剖析。     

机翼结构用复合材料的力学性能要求

本文试图从机翼结构的结构完整性要求和复合材料抗冲击性能与压缩设计许用值的关系出发,探讨适用于机翼结构的复合材料力学性能要求,以及对碳纤维和树脂性能的相应要求。     

通用飞机人为因素适航审定要求研究

介绍了国内外通用飞机人为因素发展情况,重点分析了CCAR 23部有关条款对人为因素评估的具体要求,给出了为满足人为因素适航要求提供适航验证符合性思路.     

某型飞机应急救生技术适航审定要求研究与探讨

介绍了美国联邦航空局和中国民航局关于通用飞机安装弹射座椅的适航技术要求;分析了飞机应急情况救生技术的现状及其发展趋势,以及安装弹射座椅的飞机现有的适航技术要求及规定;并对安装弹射座椅的特技类飞机适航审定提出了一种思路和建议。