运动阵列非重叠孔径扩展算法

现有线阵列被动合成阵列算法无法满足非连续信号和非均匀线阵列的处理需要,难以被直接用来提高运动线阵列对时域重叠脉冲信号的空间分辨能力.针对这一问题,本文提出一种能够同时满足对非连续信号和非均匀线阵列处理需求的运动阵列非重叠孔径扩展算法.该算法首先通过二维MUSIC算法估计运动阵列的“相位校正因子”,进而完成阵列孔径扩展实现对多个时域重叠信号的高分辨方向估计.通过仿真研究可知:小孔径运动阵列利用本算法在不牺牲方向估计精度的条件下,可以有效提高对多信号的分辨能力,且具有较好的低信噪比适应能力.     

水下声呐探测系统信息支持下的直接攻潜作战仿真

在水下声呐系统目标指示条件下,进行直接鱼雷攻潜是1种创新型战法.针对直接空投鱼雷攻潜作战问题,将水声环境信息引入鱼雷目标识别过程,建立了更为逼真的模拟法效能评估模型.仿真分析了目标定位精度,投雷参数、鱼雷搜索参数等各关键因素对攻潜作战效果的影响,提出了在水下声呐基阵目标指示直接攻潜作战时,应重点关注的若干问题.     

Source localization using a non-cocentered orthogonal loop and dipole （NCOLD） array

A uniform array of scalar-sensors with intersensor spacings over a large aperture size generally offers enhanced resolution and source localization accuracy,but it may also lead to cyclic ambiguity.By exploiting the polarization information of impinging waves,an electromagnetic vector-sensor array outperforms the unpolarized scalar-sensor array in resolving this cyclic ambiguity.However,the electromagnetic vector-sensor array usually consists of cocentered orthogonal loops and dipoles（COLD）,which is easily subjected to mutual coupling across these cocentered dipoles/loops.As a result,the source localization performance of the COLD array may substantially degrade rather than being improved.This paper proposes a new source localization method with a non-cocentered orthogonal loop and dipole（NCOLD）array.The NCOLD array contains only one dipole or loop on each array grid,and the intersensor spacings are larger than a half-wavelength.Therefore,unlike the COLD array,these well separated dipoles/loops minimize the mutual coupling effects and extend the spatial aperture as well.With the NCOLD array,the proposed method can effciently exploit the polarization information to offer high localization precision.     

Coherent optical array receiver for PPM signals under atmospheric turbulence

Adaptive combining of experimentally obtained heterodyned pulse position modulated (PPM) signals with pulse-to-pulse coherence, in the presence of simulated spatial distortions resembling atmospheric turbulence, is demonstrated. The adaptively combined PPM signals are phased up via an least-mean-square algorithm suitably optimized to operate with PPM in the presence of additive shot noise. A convergence analysis of the algorithm is presented, and results with both computer simulated and experimentally obtained PPM signals are analyzed.     

STUDY ON FLAP SIDE-EDGE NOISE BASED ON THE FLY-OVER MEASUREMENTS WITH A PLANAR MICROPHONE ARRAY

After the significant progress that has beenachieved in engine noise reduction in the last twodecades,the airframe noise of civil transportshas now become a major concern for noise certi-fication and environmental considerations.Con-sequently,aircraft manufacturers and researchcenters have been working on airframe noisewith the objectives of developing reliable noiseprediction schemes and reducing aerodynamicnoise generation at the source in recentyears[1～ 2 ] .　　 Of all the airframe noise …     

一种基于FPGA的航空发动机独立超转保护系统

针对航空发动机超转故障,提出一种基于现场可编程逻辑门阵列(FPGA)的独立超转保护系统.介绍了系统的总体设计方案、超转判断方法及故障诊断方式.该系统采用双双余度结构,通过线性分类器和时间窗内加权表决判断方法,提高超转保护功能可靠性.通过3层级机内自测试(BIT)监视静默失效,满足适航要求.硬件在回路仿真平台试验结果表明:该系统超转判断准确可靠,并能在连续判断超转后进入锁定保护状态,有效避免超转事故的发生.目前,研究成果已应用于某型发动机全权限数字控制(FADEC)系统中.      

Joint calibration algorithm for gain-phase and mutual coupling errors in uniform linear array

The effect of gain-phase perturbations and mutual coupling significantly degrades the performance of digital array radar (DAR). This paper investigates array calibration problems in the scenario where the true locations of auxiliary sources deviate from nominal values but the angle intervals are known. A practical algorithm is proposed to jointly calibrate gain-phase errors and mutual coupling errors. Firstly, a simplified model of the distortion matrix is developed based on its special structure in uniform linear array (ULA). Then the model is employed to derive the precise locations of the auxiliary sources by one-dimension search. Finally, the least-squares estimation of the distortion matrix is obtained. The algorithm has the potential of achieving considerable improvement in calibration accuracy due to the reduction of unknown parameters. In addition, the algorithm is feasible for practical applications, since it requires only one auxiliary source with the help of rotation platforms. Simulation results demonstrate the validity, robustness and high per-formance of the proposed algorithm. Experiments were carried out using an S-band DAR test-bed. The results of measured data show that the proposed algorithm is practical and effective in appli-cation.     

航天用反作用飞轮旋转变压器位置检测算法

目前,航天用反作用飞轮大多采用霍尔传感器或光电码盘进行测速。但是,霍尔传感器在反作用飞轮低速运行时精度相对较低,光电编码器的环境适应性相对较弱。基于此,提出了一种使用旋转变压器检测反作用飞轮转子位置的方法。但如果在现有飞轮控制电路中额外使用旋转变压器专用解码芯片,会导致成本大大提高,故提出了使用控制电路中的FPGA进行解码的方法。首先,介绍了旋转变压器的工作原理,通过求解反三角函数获得转子位置。其次,介绍了传统坐标旋转数字计算机(Coordinate Rotation Digital Computer,CORDIC)算法。最后,针对传统CORDIC算法无法求解完整平面角度值问题,提出了一种改进型CORDIC算法求解转子位置,并给出了一种能够减少硬件使用资源的全流水线CORDIC阵列结构。通过Modelsim仿真,证明了所提出的方法具有占用资源较少、延迟低、测量精度较高等优点,在反作用飞轮测速应用中具有良好前景。     

基于模式空间变换的圆阵无源测向算法研究

建立了均匀圆阵测向系统模型，在其基础上利用模式空间变换方法将均匀圆阵转化为虚拟均匀线阵，使得ESPRIT算法得以应用，从而实现二维无源测向。为验证算法的可行性及可靠性，搭建了七元均匀圆阵实测系统。实验结果表明，该算法所用时间较短，且测向结果较为稳定，可应用于均匀圆阵无源测向系统。     

基于3DES算法的SRAM工艺FPGA加密设计

本文提出了一种基于3DES算法的SRAM工艺FPGA加密设计方法,并详细描述了3DES加密算法的模型以及其硬件设计过程,最后给出3DES加密算法的硬件实现仿真时序图以及在FPGA中的实现结果.