基于等效时间采样原理的高速数据采集系统研究

高速数据采集技术日益成为宽带模拟信号数字化和数据处理系统中的关键技术。数据采集速度的提高对ADC等器件速度和系统结构提出了很高的要求,从而增加了系统实现难度。该文介绍的基于等效时间采样原理的高速数据采集系统,实现了用低速ADC对周期性宽带信号的高速采集。     

利用多通道、低速率采样信号重构完整宽带信号的稳健方法

对宽带信号直接采样要求模数转换器具有高采样速率,这将导致采样精度降低并且难以实现。采用将宽带模拟信号进行多通道、低速率采样的思路,提出一种利用自适应波束形成技术恢复信号完整带宽的新方法。该方法可以同时实现低采样速率与高精度,而且对通道延迟及其他误差稳健。仿真数据的处理结果验证了该方法的有效性。     

宽带直扩信号的随机解调压缩采样方法

为了有效解决扩频测控通信系统宽带化带来的高速采样压力和高数据率问题,提出了基于压缩感知的直扩信号随机解调压缩采样方法。通过对模拟信号压缩采样原理进行研究,深入分析和推导随机解调采样原理及其数学模型,提出了基于压缩感知的直扩信号采集系统构架,并对压缩比取值影响因素进行了分析;给出了随机解调压缩采样系统硬件实现方案,并对其可行性进行了分析;最后对所提出的直扩信号压缩采样方法的性能进行了仿真分析。仿真结果表明,压缩采样系统可以实现直扩信号的压缩采样处理,并能够高精度重构原信号,但重构信号的解调门限会随压缩比增大而相应提高,这是采样率降低所需付出的代价。压缩采样为宽带直扩测控通信系统提供了一种高效的模数转换和同步解调处理思路。     

基于TMS320VC5410和TLV1571的数据采集系统

为提高信号采集系统采样速度,增强系统可靠性,降低系统功耗,设计了一种基于TMS320VC5410和TLV1571的高速信号采集系统.通过TLV1571对模拟信号进行采样,然后经A/D转换后变换为数字信号,DSP通过定时中断每隔一段时间就读取一次采样数据并对数据进行处理.然后介绍这个系统的硬件电路各主要器件选择的原因、连接方法,实现方法及系统调试过程中应该注意的事项.实验结果表明这个系统完全能够满足采样速度在1.25 Mb/s信号的采集处理工作.在1.25 Mb/s的采样速度及10住采样精度条件下可以同时实现8路模拟信号的采样工作.     

MWC欠采样方法中伪随机序列的改进

最近提出的调制宽带转换器(MWC)采样方法,针对稀疏宽带模拟信号可以实现低于奈奎斯特率的不失真采样,为稀疏宽带信号采样率高的问题提供了一种欠采样方案。文中针对MWC系统在实现过程中伪随机符号序列不易精确实现的问题,提出了一种易于实现的0/1伪随机序列,简化了MWC的实现方法。通过数值仿真对MWC系统重构性能进行了检验。实验结果表明,MWC系统采用所提出的伪随机序列时仍然可以实现低于奈奎斯特率的采样,并能高概率地精确重构原信号。     

全新的高稳定穿墙雷达接收机前端设计

在穿墙雷达(TWR)接收超宽带(UWB)回波信号的过程中,高速信号采集是其中的关键所在。首先基于传统等效采样方法,改进了其采样模式,能极大地提高等效采样的实时性,并减小精密延时电路的延时时间范围。其次利用跟踪保持芯片设计了一种新型等效采样接收机前端实现方案,不仅能降低等效采样技术对取样脉冲的要求,而且能充分发挥跟踪保持芯片高重复频率、高稳定和高度集成的优势。通过分析和仿真论证,实现了10GHz的等效采样频率,理论分析与仿真测试结果一致性良好。这种高度集成、简单高效的电路在超宽带穿墙雷达接收机中具有很好的应用前景。     

MWC欠采样方法中伪随机序列的改进

最近提出的调制宽带转换器（MWC）采样方法,针对稀疏宽带模拟信号可以实现低于奈奎斯特率的不失真采样,为稀疏宽带信号采样率高的问题提供了一种欠采样方案.文中针对MWC系统在实现过程中伪随机符号序列不易精确实现的问题,提出了一种易于实现的0/1伪随机序列,简化了MWC的实现方法.通过数值仿真对MWC系统重构性能进行了检验.实验结果表明,MWC系统采用所提出的伪随机序列时仍然可以实现低于奈奎斯特率的采样,并能高概率地精确重构原信号.     

调制混合滤波器组的宽带模拟信号采样研究

对于超宽带模拟信号,很难用单个模拟数字转换器（ADC）直接进行采样。该文提出了一种新的并行调制混合滤波器组结构用于实现超宽带模拟信号的采样,首先,将每一路宽带模拟输入信号进行余弦调制,并用相同的低通模拟滤波器均匀分割输入信号的带宽;然后,采用相同的ADC将子带信号数字化;各路子带信号通过上采样器后用数字综合滤波器综合得到原宽带模拟输入信号的数字重构。综合滤波器采用总体最小二乘准则下的特征值滤波器设计方法得到。本文所提出的系统结构不需要使用高速的采样保持电路,降低了系统实现的难度,并且设计的系统具有与其它混合滤波器组相近的重构性能。仿真结果表明了本方法的有效性。      

基于时频点集特征提取方法的宽带频谱感知

提出了一种基于调制宽带转换系统(MWC)和信号时频点集特征提取的宽带频谱感知方法。首先,利用MWC实现宽带模拟信号的低速率数字采样,对采样序列进行频谱重构得到各子带信号,同时宽带信道被划分为互不重叠的子带;其次,对各子带信号进行时频聚集性分析,提取时频点集特征,完成各子带信号检测,定义宽带感知向量以确定宽带频谱的具体占用情况,实现宽带频谱感知;最后进行仿真实验,结果表明了时频点集特征提取方法的可行性,以及其对噪声的不敏感特性,验证了该宽带频谱感知方法的有效性。     

矢量信号分析中高性能模拟信号采集系统的研究

现代通信涉及大量先进技术，需要有与电子通信相关的测量仪器，以捕获和分析宽带、实时矢量信号。中频数字化技术是实现通信过程的先进手段之一。针对矢量信号分析仪中对中频模拟信号采集系统高性能的要求，文中对系统各部分设计进行简要分析，应用ADS与诺顿等效变换对系统前端模拟抗混叠带通滤波器进行设计、优化与仿真；根据有大动态范围与优良信噪比的高速ADC的工作要求，对应选用的采样时钟信号各项指标进行推导计算，并提出一种应用自适应技术提高高速ADC分辨率的方法。     

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.     

An improved parallel thinning algorithm with two subiterations

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.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

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.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

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.     

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.     

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.     

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.     

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.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

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.     

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.