多子带频域超宽带合成雷达半实物仿真

宽带合成技术是实现距离向高分辨的一种有效手段,目前频域宽带合成方法拓展至超宽带合成,合成带宽受限,合成信号质量随子带数增加而恶化。针对这些问题,提出了一种适用于频率步进线性调频信号的多子带频域超宽带合成方法,采用预失真、子带间高精延时对齐、相位自适应调整等技术对影响信号合成质量的系统失真、延时误差、子带拼接处相位跳变改进,并搭建步进频雷达半实物仿真系统以验证所提方法的有效性及合成信号性能。实验结果表明,43个28 MHz带宽的子脉冲合成的超分辨距离向信号,带宽为1.035 7 GHz,时间分辨率高达0.872 0 ns,具有良好的点目标分辨性能,未来可应用于二维合成孔径雷达超分辨成像。     

卫星广播信号上重叠发射导航增强信号的方法

提出了一种在卫星广播信号上重叠发射卫星导航增强信号的方法,将差分校正数据经过扩频后发射出去,与卫星广播信号进行频谱重叠,一起经卫星转发。通过参数设计和性能仿真可知,差分增强信号对广播信号的接收解调影响很小,差分接收机可以通过串行干扰抵消的方法从混合信号中提取出差分增强信号,实现解扩与辅助测距,解扩得到的差分校正数据可直接用于差分定位。当混合功率比为26 dB时,捕获概率达99.99%,测距精度为10.67 m,表明了此方法的可行性。     

同步轨道卫星四站时差统计定轨精度分析

基于卫星通信信号的多站时差测轨是一种重要的新型无源测轨方法,分析其定轨精度对系统 应用具有重要意义。介绍了四站时 差测轨原理与系统组成,提出了基于四站时差测量数据的自校准统计定轨策略,采用计算机 仿真了同步轨道卫星的统计定轨精度。仿真结果表明：当无系统误差时,24 h观测数据统计定轨位置误差约为11 m,预报1周位置误差约100 m;当存在系统 误差时,可用自校准方法同步估计系统误差,系统误差估计精度约为4 m,位置误差约 为120 m,预报1周的位置误差约为200 m。     

最小能量框架的跟踪干扰识别和去噪算法

讨论了基于离散信号空间上的最小能量（小波）框架的跟踪干扰信号识别和去噪算法。利用一组框架对采用相位调制的接收信号进行分解,如果受到跟踪干扰,则未干扰区信号和干扰区信号的3个分解子信号将呈现明显不同的能量分布特征,据此提出了一种跟踪干扰信号识别和自适应阈值去噪算法。理论分析和仿真结果表明,识别算法具备低虚警率和漏警率性能,而去噪算法有效抑制了干扰信号能量,10-2 误包率时,BPSK+1/2 Turbo信号中1/16尾部信号受到干信比值10 dB的高斯噪声干扰后,去噪算法获得了约4 dB的增益;而QPSK+1/2 Turbo信号中1/8尾部信号受到干信比值10 dB的高斯噪声干扰后,去噪算法可以把误包率性能从1降低至约0.67的水平。     

低信噪比下突发通信的同步检测

针对低信噪比下突发通信系统的同步检测问题,提出了一种利用接收信号平均信噪比和瞬时信噪比设置动态检测门限的同步方法,实现了信号检测门限的设置与信号脉冲出现时刻噪声能量的自适应匹配,提高了低信噪比下同步检测概率。计算机仿真表明在同步序列长度为63时,信号的有效检测工作信噪比可以降低到-5 dB。该方法适合于低信噪比下运动平台间的突发通信系统。     

阵列导向矢量在智能天线自适应算法中的应用

分析了智能天线自适应算法的基本原理,针对常用算法运算量大和测向精度有限等问 题,在接收机的输出端引入阵列导向矢量信号,利用方向性因子和协方差矩阵的特殊性 质,通过多次迭代运算得出区间内的信干噪比曲线。通过对八元直线型智能天线阵列的HFSS 仿真实验表明,两组信干噪比曲线峰值均对应期望信号方向,峰值信干噪比大于30 dB ,算法抗干扰性能良好。八元阵列天线的最大增益约为18 dB,通带内驻波比小于15 , 反射系数小于-25 dB,天线系统波束搜索性能良好,而且可以实现远距离传输。     

A Novel Tri-Band Bandpass Filter Incorporating Stub Loaded Resonator and DGS Resonator

给出了一种采用枝节加载谐振器和缺陷地面结构实现的三通带滤波器。枝节加载谐振器采用 交趾耦合实现了工作于2.45 GHz和5.25 GHz的两个通带,利用缺陷地面结构实现了 工作于3.5 GHz的另一个通带,3个通带实现了独立设计。基于该方法,设制作了一个工 作于2.45 GHz、3.5 GHz和5.25 GHz 3个无线通信频段的三通带滤波器。实测 和仿真结果对比验证了设计方法的有效性。     

高灵敏度大带宽声光信道化接收机

针对目前雷达侦察接收机难以兼顾瞬时大带宽和高灵敏度性能的紧迫形势,深入研究了声光信道化接收技术。其充分利用声光调制和空间傅里叶变换所具有的大带宽、高速度及并行处理等技术优势,并结合多级自适应积分光电转换,实现复杂电磁环境下对目标信号的高效截获。实验证明,声光信道化接收系统具有捕获信号范围宽,自适应能力强,检测灵敏度高等特点,并能有效分离同时到达信号。经样机测试,系统瞬时工作带宽为1 GHz时,信号探测灵敏度仍可高达-95 dBm,在电子侦察领域具有很高的应用价值。     

一种简单多径信道下的调制识别方法

为解决简单多径条件下调制识别类型少、难以工作于低信噪比下的问题,提出了一种基于联合特征参数的调制识别方法。根据简单多径下不考虑多普勒效应影响这一条件,利用调制信号的延迟相关和瞬时自相关特性,并结合高阶累积量特征对幅移键控(ASK)、相移键控(PSK)、频移键控(FSK)共8种信号进行分类识别。仿真结果表明,在信噪比大于4 dB时,简单多径条件下的各类调制信号正确识别率接近100%。     

基于深度学习的跳频信号识别

针对跳频信号分选存在人工提取参数特征具有复杂性的问题,提出了一种基于深度学习的识别方法。首先对跳频信号进行短时傅里叶变换,得到二维的时频矩阵;接着提取信号的轮廓特征,构造三维矩阵作等高线图,并对等高线图进行预处理;最后把预处理后的等高线图输入到卷积神经网络中进行训练、测试,进而实现分类识别。仿真结果表明,在不需要复杂的人工提取参数特征的基础上,在分选率为100〖WT《Times New Roman》〗%〖WTBZ〗时,所提方法经裁剪处理下的信噪比为-15 dB,比支持向量机和传统K-Means聚类算法都低10 dB。实测数据的算法验证表明,所提方法能够将大疆精灵4Pro、hm无人机、司马航模X8HW以及大疆悟2这四类无人机正确分类。     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.