基于FEKO的天线罩瞄准误差分析

文中采用FEKO软件对天线罩的瞄准误差进行了仿真分析.直接对真实带罩天线进行仿真,计算量过于巨大,通常工作站难以支持,因此采用等效源方法进行仿真.仿真步骤如下:首先仿真天线口面附近的等效近场;然后将等效近场作为激励源放入天线罩模型中,计算带罩天线远场差方向图;对比带罩与无罩远场差方向图零点位置的变化得出天线罩的瞄准误差.仿真结果与实测结果吻合很好,验证了仿真方法的准确性.     

天线罩三维瞄准线误差曲线的测试方法

介绍了一种在单一万向支架轴线的天线罩测试系统中,用极切角的方法测试出瞄准线误差曲线来推算出各个复合偏航和方位、俯仰角之间的三维瞄准线误差曲线的方法,并进行了实例验证此方法是有效的。用这方法测得的三维天线罩瞄准线误差曲线来分析天线罩对导弹控制回路的影响及导弹的稳定性和脱靶量是非常必要的。     

主被动复合天线罩瞄准线误差分析

在主被动复合的制导体制中，主动导引头和被动导引头分别采用幅度比较单脉冲系统和相位比较单脉冲系统情况下，天线罩所引起的瞄准线误差有一定的区别。从二种单脉冲天线的工作体制出发，分别分析了天线罩产生瞄准线误差的机理。采用这种天线罩瞄准线误差的分析方法，能评价主被动复合体制天线罩的电气性能。     

寻的导弹制导系统天线罩/导引头数学模型分析

本文从系统设计的角度描述了寻的导弹雷达导引头天线罩瞄准误差的数学模型;结合导引头分系统的数学模型,分析了天线罩瞄准误差对系统制导精度的影响及其引出的有害反馈——导弹姿态角速度耦合效应,基于系统的简化方框图及其线性描述,讨论了瞄准误差本身的取值范围和与系统几个主要参数之间的关系。最后简略地介绍了补偿天线罩瞄准误差的两种可能途径。     

一种改进的天线罩瞄准线误差计算方法

基于对带罩天线的辐射方向图数据进行处理,提出了一种改进的天线罩瞄准线误差计算方法。该方法以单脉冲天线差方向图在电轴附近的对称性为理论基础,借助等电平平均法计算天线辐射方向图的零值位置,获取天线罩瞄准线误差,降低了测试场地对天线方向图的影响,有效提高了天线罩瞄准线误差的测试准确度。     

近程导弹瞄准线转动角速度预测模型及误差分析

近程导弹采用预测瞄准线开环控制，瞄准线的预测精度直接决定导弹的命中精度。为研究瞄准线转动角速度预测误差对导弹制导精度的影响，根据捷联惯导系统坐标变换原理，建立了近程导弹瞄准线转动角速度的预测模型和预测误差模型；仿真分析了各项误差源对预测误差和命中精度的影响；提出了惯性器件的精度搭配和精度要求。研究成果为全面研究近程导弹误差模型和采取减小、补偿误差措施提供理论依据。     

天线罩误差斜率对导弹性能的影响与计量

在介绍导引头天线罩误差斜率对导弹系统稳定性和脱靶量的影响,以及根据天线罩瞄准误差测量数据计算误差斜率的公式和方法的基础上,讨论了天线罩误差斜率计量结果的不确定度,对天线罩误差斜率数据的可信度作出评估。     

提高无线电寻的制导系统精度的几个途径

本文通过分析制导系统的一些基本关系,综述了提高系统精度的可能途径。其中有减小天线罩的瞄准线误差的方法,选择飞行控制系统的要点,提高导引头随动系统稳定性的方法,改善控制对象——导弹的性能等。可供寻的制导系统的设计人员参考。     

低误差斜率导弹天线罩的设计与制造

采用常规设计的导弹天线罩一般有着较大的瞄准误差斜率,难以满足先进的导弹系统要求.在天线罩的研制实践中,开发了一套误差斜率修磨调整技术,可以显著降低天线罩的瞄准误差斜率.叙述了这种技术的原理与使用步骤,重点介绍了为减小天线罩误差斜率所完成的一系列研究工作和取得的成果.     

一种天线罩瞄准线误差测试的动态寻零方法

瞄准线误差的测试是评价天线罩电气性能必不可少的环节.文中提出了一种自动电轴跟踪的快速寻零方法.通过自动控制发射天线在扫描架上水平移动,跟踪接收天线在天线罩影响下的波束指向偏转,并记录移动距离.利用文中提出的方法对天线罩瞄准线误差进行测试,结果显示,天线的扫描范围减小了77％,测试时间仅为传统方法的0.36倍.可以看出,文中提出的动态寻零方法可有效缩短发射天线的扫描范围,提高测试速度.     

Stability of the Third Generation Intensifier under Illumination

The stability under illumination of transmission-mode GaAs photocathode sealed in the third generation intensifier is investigated by use of spectral response testing instruments. The variations of spectral response with the illumination times under weak and intense illumination are compared. The variations of photoemission performance parameters are also characterized. The results show that during initial several weak illuminations photocathode behaves no evident decay and a maximum sensitivity is achieved, while under intense illumination the sensitivity of photocathode begin to decrease largely at the first illumination. The calculated performance parameters show that the variation of surface escape probability with illumination times is a direct cause of instability of photocathode. It is also found that under intense illumination peak wavelength is moved towards short-wave and peak response is decreased, which shows that the ability of long-wave response of photocathode is decreased.     

Passive Acoustic Radar for Detecting Supersonic Cruise Missile

A Passive Acoustic Radar is presented as a necessary complement to electromagnetic wave radar, which will be expected to be an effective means for detecting cruise missiles. Acoustic characteristics of supersonic flying projectiles with diverse shapes are expounded via experiment. It is pointed out that simulation experiment could be implemented using bullet or shell instead of cruise missile. Based on theoretical analysis and experiment, the ““acoustic fingerprint““ character of cruise missile is illustrated to identify it in a strong noise environment. After establishing a locating mathematical model, the technique of acoustic embattling is utilized to resolve a problem of confirming the time of early-warning, considering the fact that velocity of sound is much slower than that of light. Thereby, a whole system of passive acoustic radar for detecting supersonic cruise missile is formed.     

Super-resolution Restoration of Remote-sensing Images

A novel image restoration scheme, which is super-resolution image restoration algorithm Poisson-maximum-afterword-probability based on Markvo constraint （MPMAP） combined with evaluating image detail parameter D, has been proposed. The advantage of super-resolution algorithm MPMAP incorporated with parameter D lies in the fact that superresolution algorithm MPMAP model is discrete, which is in accordance with remote-sensing imaging model, and the algorithm MPMAP is proved applicable to linear and non-linear imaging models with a unique solution when noise is not severe. According to simulation experiments for practical images, super-resolution algorithm MPMAP can retain image details better than most of traditional restoration methods; at the same time, the proposed parameter D can help to identify real point spread function （PSF） value of degradation process. Processing result of practical remote-sensing images by MPMAP combined with parameter D are given, it illustrates that MPMAP restoration scheme combined PSF estimation has a better restoration result than that of Photoshop processing, based on the same original images. It is proved that the proposed scheme is helpful to offset the lack of resolution of the original remote-sensing images and has its extensive application foreground.     

Design and Simulation of TF and TA Controller for Missile

A nonlinear terrain following(TF) and terrain avoidance(TA) controller is proposed for missile control systems. Based on classical TF algorithm (adaptive angle method), a new method for TF controller is proposed by using angle of attack. A method of obtaining terrain outline data from digital elevation map (DEM) for TF control is discussed in order to save store space. A TA algorithm is proposed by using bank-to-turn technique. The block control model, which is suitable for backstepping design, is given for nonlinear model of missile. Making full use of the characteristics of the system and combining block control principle and backstepping technique, a robust controller design method is proposed. Uncertainties in every sub-block are allowed, and can be canceled by using the idea of nonlinear damping. It is proved that the state tracking errors are converged to a neighborhood of the origin exponentially. Finally, nonlinear six-degree-of-freedom simulation results for the missile model are presented to demonstrate the effectiveness of the proposed control law.     

Design and Analysis of Test Schemes of Static Postponing Time on Shrapnels Used to Riot Control

The test scheme of static postponing time given in our actual national military test standard on shrapnels used to control riot is a nine-point test scheme on the combined action of three kinds of temperatures and three kinds of pressures,the consumed ammunitions are more excessive. Statistic analysis and tentative checkout about a lot of test data are done,feasibility gists are put forward for optimizing of the test design scheme. The optimizing design and data analysis of test scheme of the item are done by managing uniformity design theory, two scientific and reasonable six-point test schemes are confirmed. The feasibility and reliability of the optimizing design schemes put forward above are proved ulteriorly by test validating. The gained schemes not only have good design uniformity and little ammunition wastage and meet the test demand, but also have better forecast ability for the result data of other points using the mathematic models from the actual test points.     

Design of Non-fragile Satisfactory Estimator for Linear Continuous Perturbed Stochastic Systems

The design problem of non-fragile estimator is addressed for a class of perturbed linear continuous systems. The perturbations occur on the plant and estimator parameters. The estimator designed should force the error system to achieve the desired decay rate and force the steady error variance less than the specified upper bound irrdevancy of the admissible plant perturbations and estimator perturbations. Consistency problem of the decay rate with the variance upper bound is first considered via linear matrix inequality （LMI） approach. The solution of the estimator parameter under specifications to be consistent is then discussed. The consistency condition of specifications and estimator parameter solution are transformed to feasible or minimum problems subject to a set of LMI respectively. The method is illustrated by a numerical example.     

An Improved Scene-based Nonuniformity Correction Algorithm for Infrared Focal Plane Arrays Using Neural Networks

The improved scene-based adaptive nonuniformity correction （NUC） algorithms using a neural network （NNT） approach for infrared image sequences are presented and analyzed. The retlna-like neural networks using steepest descent model was the first proposed infrared focal plane arrays （IRFPA） nonuniformity compensation method, which can perform parameter estimation of the sensors over time on a frame by frame basis. To increase the strength and the robustness of the NNT algorithm and to avoid the presence of ghosting artifacts, some optimization techniques, including momentum term, regularization factor and adaptive learning rate, were executed in the parameter learning process. In this paper, the local median filtering result of Xij （ n ） is proposed as an alternative value of desired network output of neuron Xij （ n ）, denoted as Tij （ n ）, which is the local spatial average of Xij （ n ） in traditional NNT methods. Noticeably, the NUC algorithm is inter-frame adaptive in nature and does not rely on any statistical assumptions on the scene data in the image sequence. Applications of this algorithm to the simulated video sequences and real infrared data taken with PV320 show that the correction results of image sequence are better than that of using original NNT approach, especially for the short-time image sequences （several hundred frames） subjected to the dense impulse noises with a number of dead or saturated pixels.     

Piecewise Filter of Infrared Image Based on Moment Theory

The disadvantages of IR images mostly include high noise, blurry edge and so on. The characteristics make the existent smoothing methods ineffective in preserving edge, To solve this problem, a piecewise moment filter （PMF） is put forward. By using moment and piecewise linear theory, the filter can preserve edge. Based on the statistical model of random noise, a related-coefficient method is presented to estimate the variance of noise. The edge region and model are then detected by the estimated variance. The expectation of first-order derivatives is used in getting the reliable offset of edge. At last, a fast moment filter of double-stair edge model is used to gain the piecewise smoothing results and reduce the calculation. The experimental result shows that the new method has a better capability than other methods in suppressing noise and preserving edge.     

Bistatic Sonar Localization Based on Best Linear Unbiased Estimation

A best linear unbiased estimation （BLUE） algorithm for bistatic sonar localization is proposed. The Cramer-Rao bound for bistatic Sonar and the geometrical dilution of precision （GDOP） in different conditions are given. The simulation results show that the location accuracy of BLUE algorithm is higher than the weighted least square method.     

Research on Gear-broken Fault Diagnosis in a Tank Gearbox

A fault diagnosis method of working position gear in a tank gearbox is put forward based on simulating the fault of working position gear in an actual tank, extracting the envelope of vibration signal by Hilbert transformation amplitude demodulation method, and zooming the low-frequency band to envelope signal.