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对于大型的二维相扫雷达天线阵列,数字波束形成通常在子阵上完成,以减少数字接收机的数量并降低成本。基于子阵级数字波束形成,文中提出了一种改进的自适应信号处理架构,在低成本的情况下,同时抑制多个主副瓣干扰,并保持对目标的单脉冲测角精度。首先,每个子阵内部形成非自适应的波束并转化为数字输出;再利用行和列波束的分维特性,在子阵级形成自适应波束,进行干扰抑制处理;最后,分别将各个行或列波束合成为全阵列的俯仰或方位和差波束,用于目标的单脉冲测角。与传统的四通道抗主瓣干扰相比,该方法在合成和差波束前,基于子阵级数字波束完成自适应干扰的抑制。因此,充分利用了有限的自由度,挖掘了子阵级数字阵列抗同时多个主副瓣干扰的能力。还结合相控阵雷达实例,给出了仿真结果,验证了该方法的有效性。总的来说,所提出的阵列信号处理架构,在降低系统复杂度和成本的同时,大大提高了雷达系统的抗干扰能力。 相似文献
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在传统的数字波束形成雷达系统中,为了抑制主瓣干扰,并保持对目标单脉冲角度估计的精度,需要同时形成四个波束。对于大型的雷达天线阵列,数字波束形成通常在子阵上完成。但是对于非矩形天线阵结构,传统的自适应波束形成架构不再适用,单脉冲角度估计的精度会大幅降低。文中针对非矩形平面阵列,提出一种新的自适应波束形成方法。首先,需要对四个接收波束的输出做线性补偿,该补偿因子可通过阵列流形精确计算获得;其次,进行自适应主瓣干扰对消处理;再进行二维数字单脉冲测角。文中在理论推导的基础上,结合相控阵雷达阵列实例给出仿真结果,验证了该方法的有效性。 相似文献
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当存在主瓣干扰的情况下,采用常规的自适应波束形成技术会使单脉冲曲线严重失真,从而导致无法对感兴趣的目标正常测角及跟踪。为了在抑制主瓣干扰的同时能基本保持自适应单脉冲比曲线不失真,提出了一种基于多点约束的自适应单脉冲测角方法,该方法采用约束自适应波束形成技术,即在自适应抑制干扰的同时选取多个约束点对用于测角的单脉冲比进行约束,从而大大提高了存在主瓣干扰下单脉冲测角的性能。计算机仿真实验证明了该方法的有效性。 相似文献
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当今电子战中,常使用组合干扰战术,同时抗多个主副瓣干扰成为雷达系统面临的巨大挑战。矩形相控阵可以合成四个通道波束,并利用差波束对消和波束内的一个主瓣干扰,保持对目标的探测性能和测角精度。全数字化的相控阵可采用行列自适应波束合成,充分利用数字阵的自由度,同时抑制多个主副瓣干扰,提升了雷达同时抗干扰的能力。为进一步提高雷达的抗干扰和目标探测性能,文中提出一种新的两级架构,首先采用高增益的辅助窄波束消除主瓣干扰;然后,自适应合成和差波束并做单脉冲测角。该方法将干扰对目标探测性能的影响降到了最小。 相似文献
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常规自适应单脉冲方法在主瓣干扰下会引起自适应波束形成性能恶化并导致其单脉冲比曲线严重失真,影响被动雷达的测角精度与跟踪性能。针对此问题,提出了一种适用于平面阵的基于协方差矩阵双层重构的稳健自适应单脉冲测角方法。首先,利用Capon功率谱通过稀疏重构法初步估计出干扰加噪声协方差矩阵,通过干扰导向矢量估计完成对协方差矩阵的优化校正以提高自适应波束形成性能;然后,基于线性约束最小方差(Linearly Constrained Minimum Variance, LCMV)准则对方位角和俯仰角进行联合线性约束以避免单脉冲比曲线在主瓣干扰下严重失真;最后,根据自适应单脉冲比值求出目标与波束指向之间的偏转角以实现目标测角。与常规方法相比,所提方法在干扰抑制能力与测角精度上都有显著提升。 相似文献
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Michael Reilly 《半导体技术》2004,29(12)
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. 相似文献
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Thomas M.Trexler 《半导体技术》2004,29(5)
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. 相似文献
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The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation. 相似文献
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The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high. 相似文献
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Today, micro-system technology and the development of new MEMS (Micro-Electro-Mechanical Systems) are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible. 相似文献
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Qi-jiang Ran Pei-de Han Yu-jun Quan Li-peng Gao Fan-ping Zeng Chun-hua Zhao 《光电子快报》2008,4(4):239-242
This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel's. 相似文献
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Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers
A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it. 相似文献
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A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working. 相似文献
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It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output(MIMO) communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory. 相似文献
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《中国通信》2014,(7)
正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks 相似文献