随机二相码调相PD引信的距离旁瓣抑制

随机二相码调相ＰＤ（脉冲多普勒）引信，是一种较为新颖的噪声调制引信体制。因距离旁瓣的存在会使该体制引信产生概率性的距离模糊，首先分析了其独特的距离旁瓣特性，然后分析了相关器组法进行距离旁瓣抑制的机理和性能，并提出了以限制码的最大游程加惯性积累电路来抑制的方法。分析表明，两者都能对距离旁瓣进行有效的抑制，而后者更适合于引信电路的特点。     

RAM技术在隐身飞行器薄型翼设计中的应用

雷达吸波材料（ＲＡＭ） 技术是隐身技术中的重要技术之一，并且在隐身武器，尤其是隐身飞行器系统设计中得到广泛应用。本文首先简要阐述了雷达吸波材料吸波的基本原理，然后以隐身导弹薄型弹翼的低雷达散射截面（ＲＣＳ） 设计为例，探讨了涂覆型雷达吸波材料涂覆方案的设计思想和方法，最后给出一部分隐身飞行器薄型翼面低ＲＣＳ设计的样例。     

合成孔径雷达系统通道带宽优化设计方法研究

针对合成孔径雷达(SAR)图像质量指标与系统通道带宽的关系,对通道带宽进行优化设计。以Butterworth带通滤波器为例模拟SAR系统通道特性,利用驻定相位原理推导了滤波器引入的相位误差的表达式。引入通道带宽系数的概念,对相位误差进行勒让德正交展开,得到相位误差均方差与带宽系数和时间带宽积之间的定量关系式,进而确定带宽系数与图像质量指标之间的定量关系。在此基础上,提出SAR系统通道带宽优化设计方法,给出了带宽系数的下限,为SAR系统工程带宽设计提供了理论基础。     

星载合成孔径雷达的辐射校准

星载合成孔径雷达（ＳＡＲ）的辐射校准用于从ＳＡＲ图像演绎出雷达后向散射系数σ°。着重从端到端系统的角度阐述辐射校准原理；详细介绍内部校准和外部校准过程，并给出若干实例；还对校准误差源进行了较深入的讨论。     

对合成孔径雷达的移频干扰研究

从分析脉冲压缩信号时延和频移的耦合特性出发，推导了移频干扰对采用脉冲压缩信号体制的合成孔径雷达（SAR）的干扰输出形式，研究表明移频干扰的移频量与合成孔径雷达方位向处理的多普勒带宽无关，但只能形成点目标或线目标干扰。为此，提出了两种改进的移频干扰新样式——随机移频干扰和步进移频干扰。改进的移频干扰样式能够形成一个干扰区域，克服了固定移频干扰不能掩护分布目标的不足。理论分析和仿真表明，改进的移频干扰样式可掩护分布目标，由于可获得一维和二维信号处理增益，干扰效果优于噪声干扰。     

一种检测ＳＡＲ图像边缘的方法

传统算法不能很好地解决合成孔径雷达（ＳＡＲ）图像边缘检测问题，为此提出了一种改进方法：将Ｈaralick曲面拟合法和改进的广义模糊算子（ＧＦＯ）两种算法相结合，分别独立求出ＳＡＲ图像边缘，然后将分别求出的图像边缘合并，得出最终边缘，用实际ＳＡＲ图像对该算法进行检验，验证了该算法的有效性。     

相控阵雷达扫描波位和扫描时间的设计与优化

详细讨论了在相控阵雷达设计中扫描波位如何确定的问题。扫描波位的确定原则是使雷达系统既满足一定的检测概率和作用距离，又能在最短的时间内扫描整个空域。这就必须在波位驻留时间和平均增益损失等因素之间进行折衷。为了进一步节省扫描时间，还对如何利用数字波束形成（ Ｄ Ｂ Ｆ） 技术实现优化进行了探讨。     

ESA’s process for the identification and assessment of high-risk conjunction events

ESA’s Space Debris Office provides an operational service for the assessment of collision risks of ESA satellites. Currently, the ENVISAT and ERS-2 missions in low Earth orbits are covered by this service. If an upcoming high-risk conjunction event is predicted based on analysis of Two-Line Element (TLE) data from the US Space Surveillance Network, then independent tracking data of the potential high-risk conjunction object are acquired to improve the knowledge of its orbit. This improved knowledge and the associated small error covariances derived from the orbit determination process scale down the position error ellipsoid at the conjunction epoch. Hence, for the same miss-distance, in most cases an avoidance manoeuvre can be suppressed with an acceptable residual risk.     

An optimal selection of probability distribution functions for unsupervised land cover classification of PALSAR-2 data

Different types of classification techniques are available in the literature for the classification of Synthetic Aperture Radar (SAR) data into various land cover classes. Various SAR images are available for land cover classification such as ALOS PALSAR (PALSAR-1, PALSAR-2), RADARSAT and ENVISAT. In this paper, we have attempted to explore probability distribution function (pdf) based land cover classification using PALSAR-2 data. Over 20 different statistical distribution functions are analyzed for different classes based on statistical parameters. Probability distribution functions are selected based on Chi-squared goodness of fit test for each individual class. A decision tree based classifier is developed for classification based on the selected pdf functions and its statistical parameters. The proposed classification approach has an accuracy of 83.93%.     

Fast coating analysis and modeling for RCS reduction of aircraft

In order to fast analyze the aircraft Radar Cross Section(RCS) and accurately reduce it with Radar Absorbing Materials(RAM), a comprehensive analysis method based on Higher-Order Method of Moments(HOMOM), termed Locally Coating Method(LCM), is proposed in this paper. There are two steps to fast analyze coatings for RCS reduction in this method: analyze the RCS of various parts before coating the aircraft; model a coating over the aircraft and analyze the wave absorbing effect of it. The aircraft RCS is calculated as a whole but analyzed in various parts by LCM, and thus the RCS contribution of different parts can be compared without disturbing the current continuity. A model expansion algorithm is also presented in LCM to model absorption coatings on specified aircraft parts for later stage RCS calculation of the coated aircraft.