基于实测地形的米波雷达测高方法

基于二次雷达高度信息对地形参数进行优化的合成导向矢量算法对米波雷达测高具有较高的精度,但在没有二次雷达信息的情况下,测高精度较低。鉴于此,本文提出了一种基于实测地形的测高方法,首先对目标方位的地形起伏进行遍历,通过球面模型计算得到对应的反射点距离,将其与真实反射点距离差值最小的位置作为真实的反射点位置,然后将其距离和地形高度用于合成导向矢量算法测高,文中并给出了减小运算时间的优化算法流程,实测数据验证了该方法的有效性。     

基于DDS技术的三坐标雷达目标模拟器

针对一种三坐标雷达故障检测和在线模拟训练需求,文中设计一款雷达目标模拟器。该目标模拟器基于直接数字频率合成技术,采用数字信号处理器+现场可编程阵列+直接数字频率合成硬件架构,通过软件配置生成一组和、差模拟中频回波信号,可模拟特定方位、俯仰以及距离的雷达目标回波。采用该目标模拟器进行系统联试,结果表明该模拟器控制简单、运行稳定,便于扩展。     

基于MapX实现雷达信号模拟器中态势图显示功能

为了在雷达信号模拟器中显示目标及其所在平台的位置信息,结合地理信息系统控件MapX,分析了雷达信号模拟器中如何实现地图显示及平台动态运动等功能,并给出了计算目标距离和角度的方法,能够较好地满足系统的功能要求,使显示效果更逼真。     

用于防撞的三维毫米波雷达设计

受波束调度灵活性、接收通道数目限制,目前分集相控毫米波防撞雷达主要采用距离/方位二维扫描.由于缺乏目标高度信息,若雷达前方出现不影响载体通行的高/低目标,容易造成防撞雷达的障碍误报.针对这一问题,本文提出基于MIMO和分集相控雷达结合的天线排布和信号处理方法,实现对场景的三维检测.与二维防撞雷达相比,该方法在不增加雷达接收通道数且几乎不增加雷达尺寸的前提下能有效实现方位和俯仰的联合测角.与二维稀布接收阵雷达相比,本文设计雷达不会产生方位栅瓣,适合复杂背景下的多目标检测.     

微机程控通用雷达目标模拟器

雷达目标模拟器是一种用来产生模拟的目标回波信号的装置,在雷达设备的研究、维护和使用等领域广泛的用途。本文介绍一种通用雷达目标模拟器,这种目标模拟器由微机进行控制,可以用程序设定信号的特性,从而可以产生具有复杂特性的目标回波信号,例如具有多个运动目标、有一定的杂波背景等等。而且,这种目标模拟器可以与不同型号雷达的方位和定时脉冲实现同步, 生相应的雷达回波信号,因而具有广泛的用途。     

三座标战术对空监视雷达

本文是一篇评论几种类型的能提供目标高度和距离、方位的三座标战术对空监视雷达的文章。这些雷达包括采用叠接波束、频扫或相扫以获得仰角覆盖且采用机扫以获得360°方位覆盖的各种雷达。机载雷达和机载武器系统处于近距离时需要三座标雷达。这些近程系统和性能局限的飞机导致对目标高度精度的严格要求。显然,为了引导战斗机去截击敌机,必须同时提供高度信息和距离、方位信息。     

一种新颖的多目标模拟器

介绍了一种多目标模拟器及其特点,利用该模拟器可以模拟几十个方位、俯仰、距离都不同的目标,阐述一种新颖的多目标模拟器与雷达系统的工作过程,最后给出模拟器与雷达系统的信号流及模拟器角度控制器的组成框图。     

雷达导引头DBS回波信号模拟器设计

半实物仿真是雷达导引头研制过程中性能评估及验证的有效手段,为实现在实验室内对雷达导引头DBS成像算法的评估验证,设计一种基于FPGA和DSP硬件实现的DBS回波信号模拟器,实现了目标方位上回波信号的模拟。模拟器的数据采集结果经DBS成像处理后,与理论仿真结果进行对比分析,验证了所设计雷达导引头DBS回波信号模拟器的正确性。该模拟器已成功应用于导引头研制阶段DBS成像算法的评估验证。     

试析雷达信号处理系统的关键技术

雷达主要通过发射电磁波对目标进行照射并接收其回波,由此获得目标至电磁波发射点的距离、距离变化率(径向速度)、方位、高度等信息,雷达的信号处理系统是雷达系统的最重要的组成部分,主要由发射机、发射天线、接收机、接收天线几个部分组成,发射机的功能是产生某一所需功率电平的射频波形,天线的基本功能是将射频能量从雷达传输线耦合到传播介质中或由传播介质耦合给传输线。接收机的主要功能是接收微弱的目标信号,并将信号放大到可以使用的电平,显示器的基本功能和用途是将目标信息传递给用户。本文主要对雷达信号处理系统的关键技术进行简要分析,希望能为相关的研究提供部分参考价值。     

雷达目标三维成像算法研究

逆合成孔径雷达三维成像技术可有效揭示雷达目标散射源的空间分布;相比于传统的距离向和方位向二维成像,三维成像又增加了俯仰向的分辨能力,可以识别雷达目标高度方向的散射源分布情况。从雷达目标回波信号分析出发,探讨了三维成像的基本公式及算法。距离向分辨采用传统的FFT(快速傅里叶变换)实现,方位向和俯仰向分辨运用卷积反投影算法实现。讨论了两种实现方位向和俯仰向成像的投影插值算法,即二维投影插值法和直接投影法,与传统的二维投影插值算法比较,直接投影法具有计算速度快和计算精度高的优点。     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

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正Communications—VLSI Researches and industries of telecommunications have been growing rapidly in the last 20 years and will keep their high growing pace in the next decade.The involved researches and developments cover mobile communications,highway and last-mile broadband communication,domain specific communications,and emerging D2D M2M communications.Radio communication steps into its