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随着对地观测技术的快速发展,遥感卫星空间分辨力的不断提高,星地链路传输的信息量越来越大,码速率越来越高,数据传输频段已经由传统的X频段扩展到Ka频段,以满足海量遥感数据传输的需求。但Ka频段低轨遥感卫星波束非常窄,遥感卫星地面接收系统需要具备良好的跟踪性能,才能实现系统稳定的捕获跟踪,保证接收数据的质量。文中通过对跟踪方式和跟踪精确度方面进行分析和论证,优化捕获跟踪流程,实现对低轨遥感卫星Ka频段的捕获跟踪。文中提出利用S频段跟踪引导Ka频段跟踪的方式,高低仰角采用不同的优化流程设计,结合高分辨力对地观测系统重大专项的先期研究内容和某地面接收站进行了设计验证,结果表明,可实现低轨遥感卫星Ka频段的捕获跟踪,待时机成熟,可进行工程应用。 相似文献
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跟踪与数据中继卫星系统搭建了中低轨航天器及其地面站通信的桥梁,实现了信息的实时传输,并提高了突发事件的应对能力。为对跟踪与数据中继卫星系统(TDRSS)调度业务的质量以及效率进行有效评估,在STK功能和接口的基础上,提出了基于STK通信组件(STKX)的跟踪与中继卫星实时场景仿真及其原型系统实现的技术方法,设计并实现了中继卫星针对中继业务的运行可视化系统。仿真结果表明,基于STKX的仿真平台能够满足中继卫星地面终端对中继任务的实时任务监控以及业务调度评估需求。 相似文献
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新一代高效卫星导航信号研究 总被引:1,自引:0,他引:1
本文介绍了以连续相位载波形式构建导航卫星信号,将测距码的随机性承载在相位变化率上,在具备很高的频谱利用率的同时,更利于锁相环结构捕获与跟踪信号。使下一代GNSS具备多频段和多频点灵活部署能力,并可实现导航数据与其他信息的高速率数据传输。 相似文献
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针对深远海和陆基间高速率实时数据通信需求,完成了一种应用于低轨卫星的高集成度、低成本、低功耗L频段中继通信载荷的设计和实现。该中继通信载荷将通信天线、射频前端、信号处理单元、电源变换单元和接口单元等集成化设计。接收前端采用有源相控阵天线设计,发射前端设计了GaN功率放大器以提高接收单元獹/T值和发射单元等效全向辐射功率(Effective Isotropic Radiated Power,EIRP)。信号处理单元集成了零中频接收结构和直接射频调制结构,可完成反向链路8Mb/s载荷数据接收解调及前向链路数据处理转发的功能。载荷单机和装星后的环境模拟测试以及星地通信回路模拟测试结果表明,装星载荷可实现L频段卫星通信。整机质量为12.87 kg,在工作温度-25℃~+55℃范围内,发射端功率放大器输出大于30 W时,最大功耗为91.2 W(3.04 A/30 V)。 相似文献
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中低轨航天器中继终端常采用自动跟踪技术,完成对数据中继卫星的捕获跟踪,建立高速数据中继传输链路。文章针对中继终端应用需求,给出了一种典型的单通道单脉冲接收设备主要性能设计,通过MAT-LAB/Simulink软件仿真验证证明设计可行。 相似文献
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中继通信无人机天线自动跟踪平台设计 总被引:1,自引:0,他引:1
为了进一步扩展微小型无人机中继通信的覆盖范围,提高通信带宽和通信质量,设计研制了基于信号接收强度(RSSI)盲估计跟踪的天线自动跟踪平台,通过实时获取通信接收机的RSSI实现地面定向天线对中继无人机的动态跟踪。采用卡尔曼滤波算法对提取的RSSI信号进行优化处理;利用矩形扫描方式提高初始捕获速度;利用单天线步进式“十字”跟踪方法完成天线动态跟踪。设计了自动跟踪平台的软硬件并进行了测试,结果表明:设计的跟踪平台具有较好的跟踪速度与跟踪精度,能满足无人机对定向天线自跟踪的需要。 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 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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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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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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GU Min-fen LIANG Zhong-cheng WANG Ren-zhou DONG Xiang-mei ZHANG Pei-ming CHEN Jia-bi 《光电子快报》2008,4(2):150-152
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. 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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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. 相似文献
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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. 相似文献
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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. 相似文献