交叉极化干扰对阵列雷达测角影响研究

为研究复杂电子对抗环境下雷达性能受干扰情况,本文研究了交叉极化干扰对极化融合单脉冲阵列雷达测角性能的影响。首先,阐述了阵列雷达极化融合单脉冲测角方法。然后,理论分析了交叉极化干扰对极化融合单脉冲阵列雷达测角性能的影响,从数学上证明了该干扰方法可带来极化融合测角的误差项,导致测角精度下降。最后,提出了采用辛格函数导数的变体函数对子阵交叉极化方向图进行模拟,并在此基础上对极化阵列雷达的测角性能进行了交叉极化干扰仿真,得到了测角精度随交叉极化干扰强度变化曲线和测角性能下降率与目标回波极化比的关系。研究表明,交叉极化干扰会导致阵列雷达测角性能下降,交叉极化干扰分量与目标回波共极化分量相近时对测角影响较大,并且,目标回波的极化比越小,即目标的交叉极化分量越小,雷达受干扰越明显,测角性能下降越大,性能降低10%左右。     

相干两点源对比相单脉冲测角的干扰机理分析

相干两点源干扰是对单脉冲角跟踪系统的重要干扰手段之一,许多文献都详细分析并推导了相干两点源对比幅单脉冲系统的干扰角度增益公式,但对比相单脉冲系统的干扰机理分析还未见分析,有必要对该问题展开深入分析。文中在已有的基础上,分析了对比相单脉冲测角的干扰机理,得出了与比幅单脉冲一致的干扰角度增益公式,完善了相干两点源对单脉冲测角的干扰机理的理论。     

被动单脉冲导引头数字测向

在比幅比相被动雷达导引头测向的基础上,提出了一种单脉冲的数字化测向技术,该方法把比幅和比相测向数据在频域处理,具有抗干扰能力强,精确度高,对多个同时到达的信号测角的特点,最后对微波接收电路幅相不一致的特点提出了一种校准方法。     

采用小波预处理器提高单脉冲雷达测角精度

简要介绍了小波多分辨分析的主要理论，对单脉冲雷达角闪烁误差进行了归纳分析，对未来单脉冲伺服系统中如何应用小波预处理器提高其角度测量精度进行了理论上的探讨。     

末制导雷达抗拖曳式干扰的方法研究

针对现有末制导雷达容易受到拖曳式干扰问题,提出一种基于目标和干扰的极化特性差异的干扰抑制方法。建立弹载单脉冲雷达的全极化接收信号模型,给出干扰极化参数的估计方法,并利用极化滤波对干扰进行抑制,最终实现单脉冲测角。在此基础上,分析目标的极化特性对干扰抑制性能的影响。理论分析和仿真结果表明,在极化域能够有效地抑制拖曳式干扰。     

多线性约束结合自适应单脉冲测角方法

传统单脉冲算法是针对空域高斯白噪声背景下单目标的一种有效测角算法。文章针对色噪声背景加强旁瓣干扰条件下,自适应空域滤波抑制干扰的同时,主波束内鉴角曲线畸变引入新的角度估计误差的问题,研究了多约束线性结合自适应单脉冲测角方法,该方法适用于阵元级和子阵级自适应空域滤波,仿真结果表明,该方法能有效地改善自适应空域滤波时主波束内鉴角曲线畸变。     

基于非圆信号对阵列干扰下的最佳阵元数研究

针对理想情况下,空间谱估计算法的测向性能随阵元数目增加而提高,然而实际工程中存在通道不一致和互耦等干扰,使阵元数目与测向精度不再成正比问题,提出一种研究最佳阵元数的方法。在阵列干扰条件下,利用非圆信号的伪协方差矩阵不为零特性,基于空间谱估计算法,以测角精度和测向成功概率为指标,分别在均匀线阵和均匀圆阵下研究最佳阵元数目。通过仿真分析得出,研究不同阵列形式下的不同目标个数的最佳阵元数目,对抗干扰至关重要。     

单脉冲雷达导引头抗噪声干扰性能分析与验证

噪声干扰是雷达导引头需要对付的主要干扰形式之一。在压制式噪声干扰下,导引头由主动工作模式转为向干扰源寻的(HOJ)的被动工作模式,单脉冲雷达导引头可以从噪声干扰中提取出角跟踪误差信号,保持对目标稳定跟踪。但是在强噪声干扰下,导引头接收机处于饱和状态,失调角及测角方差恶化,从而使其不再具有任何利用价值,必须采取措施加以解决。     

闪烁干扰对导弹的干扰效果分析

分析给出实验条件下双机闪烁干扰的干扰效果并得出该条件下的导弹分辨角.在最大可用过载下对导弹的极限侧边界进行了仿真,通过极限弹道计算出闪烁干扰和恒功率非相干干扰下的导弹攻击区域;并在假定导弹制导误差服从瑞利分布条件下,对两种干扰条件下单发导弹的毁伤概率进行对比评估,说明了闪烁干扰的优势所在.     

新型无源探测系统中的超分辨测向算法研究

本文在分析了超分辨测向原理的基础上,提出了将超分辨测向方法应用于新型无源探测系统.根据系统要求,采用6单元线阵,建立了线阵空间谱估计超分辨测向的数学模型及算法流程,针对系统中的关键技术指标进行了计算机仿真验证,并取得了较好结果.为超分辨测向算法用于新型无源探测系统的可行性提供了工程技术参考.     

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.     

Expert Systems Aimed at General Design of Projectiles

Expert systems aimed at the general design of projectiles can implement a series of intelligent designs, such as the design of HE shell, the scheme expounded and proved, the emulation analysis and calculation, etc. Aiming at the product design feature, the expert system adopts the object-oriented knowledge representation and all kinds of inference control engines to describe and reason the relevant knowledge regarding the product through the microcomputer. It embodies the foundation of emulation analysis and simulated manufacturing of the shell. It makes use of the method that knowledge expression is combined with condition of inference to carry out the overall design and emulation and reference.The paper gives the ways through which the functions can be achieved, gives the modularization of reference and the design methods of systematization, puts forward the method of knowledge expression and working interface, and supplies a platform for similar products of the shell category that can be quickly designed.     

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.