基于FPGA和USB接口的多通道数据采集系统

针对实现多通道测距雷达信号的数字化采集的目的．设计了一种基于FPGA和USB接口的多通道数据采集系统。该系统采用在FPGA芯片中构建多个数字逻辑模块的方法,实现对AD芯片模数转换过程的控制。并利用IP核在FPGA中构建存储器,对采样得到的数据进行缓存,最后通过USB2．0接口芯片将缓存中的采样数据及时传输至上位机。通过...     

基于FPGA的多通道采集传输模块的设计

由于多通道体制的声纳具有高信噪比和高精度等特性,它已经成为当前声纳的主流。因此,多通道信号的实时、高效采集尤为关键。本文提出了一种基于FPGA的多通道声纳采集模块,它利用FPGA产生AD芯片的控制信号,并将采集到的串行数据转换为并行数据,最后将采集到的数据传至信号预处理模块。该设计具有高精度、低噪的特点,可同时对多路信号进行AD采集、处理和传输,采集数据有效位数达12bit,采样频率可达240Ksps。     

基于PXI总线的航空串行总线专用通讯模块研制

ARINC429在航空航天等领域应用广泛,RS 232是常用的计算机与外部设备接口。作为某军事领域电子系统测试平台的一部分,设计了基于PXI总线的ARINC429和RS 232的专用通讯模块。以DSP和FPGA联合作为控制器,实现通讯模块的PXI接口,基于专用的协议芯片DEI1016实现ARINC429通讯,由FPGA为协议芯片提供时序和数据的缓存FIFO,并在FPGA中集成了RS 232协议编解码。测试表明,该通讯模块能实时可靠灵活地收发数据,实现对被测电子系统多路ARINC429和RS 232总线的测试。     

话音和数据在远距离光纤通信系统中的传输

设计了一种基于FPGA的用于传输话音和RS232串口数据的远距离光纤通信系统.该系统分别由话音信号处理电路、RS232接口电路、光电信号处理模块和FPGA控制电路组成.系统具有传输话音清晰、数据传输误码小、传输距离远以及安装方便等特点.     

基于m序列的半导体激光测距技术研究与仿真

针对传统脉冲式半导体激光测距机在中远程测距的应用中,回波信噪比过低而难以检测目标信号的问题,提出了一种基于m序列的小型化半导体激光测距方案,以单周期m序列作为激光发射波形,对微弱低信噪比回波信号采用相参积累及匹配滤波相结合的数字信号处理方法。通过仿真及计算,证明本方案可以提高回波信噪比,并有效地从微弱回波信号中提取出目标信号,进而提高激光测距机的测距能力。     

通用型多通道高速数据采集记录仪

目前数据采集记录仪体积较大,采样频率低,记录通道少,记忆空间易受干扰而多变。本系统以Xilinx的Virtex-5系列现场可编程门阵列(FPGA)芯片XC5VLX30作为核心控制单元;采用ADI公司的高速AD进行模数转换;外围采用多片并口存储器作为存储单元,延长记录时间。本系统能够采样16通道以上、精确度8位模拟信号,采样速率能达500 Mbps以上,并把采样数据无线传输给上位机进行处理。     

基于多波束风场位移测量法的高速数据采集和处理系统设计

为实现对风场的实时监控,多波束风场位移测量系统对数据采集系统提出了很高的要求。针对实际需求,设计了实现高速数据缓存和传输控制的FPGA芯片,主要包括PLL时钟管理模块、前级FIFO缓冲模块、后级双口RAM存储模块以及FIFO和RAM的读写控制模块等,很好地完成了数据的缓存和异步读取,并且极大简化了A/D芯片接口电路结构和印制电路板设计的复杂性。在开发环境QuartusⅡ6.1中对设计的各个模块分别进行了综合和仿真,仿真结果表明各模块均达到了设计要求。风场位移测量系统成功地对实地风场进行了测量,结果表明高速数据采集系统能够有效地检测出风场中不同距离处的散射回波信号,并据此计算出风速以及风向。     

基于单片机技术的数据采集系统的设计

介绍了基于单片机技术的数据采集系统的硬件设计和软件设计.该系统以AT89C51单片机为核心,TLC2543作为A/D转换器, 通过RS232通信接口,实现单片机与PC机间的采集数据的传输.该系统分为数据采集传输和数据显示两大模块,数据采集通过单片机控制TLC2543芯片实现A/D转换,并通过RS232实现单片机和PC机间采集数据的传输.数据显示模块,通过在Visual Basic开发环境下,运用VB提供的通信控件MSCOMM来实现上位机对采集数据的收集和显示.     

基于回波信号插值重建的峰值判别技术

在脉冲式激光测距技术中,测量距离和目标反射特性变化等因素会引起微弱回波信号的峰值判别误差,造成激光飞行时间的测量误差,峰值判别误差是影响激光测距精度的主要因素之一.针对激光测距中微弱回波信号不规则引起的峰值判断精度低的难题,采用FPGA控制采样电路对回波信号进行高频采样,通过软件对采样数据进行插值重建,根据重建图形判断出回波信号的峰值点位置作为计数停止点,有效提高了回波信号峰值判别精度.实验证明:采用该项技术的激光测距机能够达到0.1 m测距精度.     

基于高速相关采样的锁模激光回波实时检测

针对锁模激光器微弱回波信号探测的需求,提出了一种基于高速相关采样和在线实时并行累加处理算法相结合的方法,对传统的模拟取样积分方法进行了改进,可实现无参考信号条件下的实时数字累加检测。设计并实现了一套基于该方法的锁模激光器微弱回波信号检测原型系统,使用12 bit@900 MSPS模拟-数字转换芯片（ADC） ADS5409对经光电转换之后的锁模激光回波信号进行波形采样,并利用现场可编程逻辑门阵列（FPGA）芯片Kintex-7实现对ADC的控制及在线数据处理。系统测试结果表明,对于重复频率为8 MHz、平均功率为0.04 nW的锁模激光回波信号,通过在FPGA内进行16 000次脉冲波形精确累加,可实现信号的有效检出,且从波形采集完毕到输出检测结果的延时小于100 ns,达到了高度的实时性。经900次重复实验,检测效率达到100%,且无虚警情况发生。     

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.     

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.     

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.     

Study of waveguide coupling efficiency in hybrid silicon lasers

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.     

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.     

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.