脉冲调制信号分析与测量方法

本文主要介绍用频谱分析仪对脉冲调制信号脉冲频谱载波功率进行直接测量后转换成峰值功率的方法,并系统地分析了窄带和宽带状态下脉冲调制信号频谱及功率测量的差别。这对雷达信号应用时的脉冲功率测量具有实用性。     

频谱分析仪高级操作进阶

频谱分析仪作为频域信号分析仪器,除了常规的测量信号幅度,频率占用特性应用外还被用于相位噪声测量,信道功率,邻道功率测量,带宽占用测量,杂散发射检测、三阶互调以及EMC测试等高级应用,这些应用都是基于频谱分析仪基本功能的扩展,对信号进行特定的分析。     

频谱仪在卫星通信系统中的应用探讨

频谱分析仪广泛应用于微波技术领域,是在频域内对信号的电平、功率、频率等参数进行测量并显示的仪器,文章从频谱分析仪的原理出发探讨了其作为测试仪器在卫星通信中的应用.     

射频信号相位噪声测量不确定度分析

在雷达信号测量中,对连续波信号我们一般用扫频式频谱分析仪对信号频率、功率、谐波分量及相位噪声进行表征。本文着重研究了在利用扫频式频谱仪测量信号相位噪声时,信号谐波分量与相位噪声测量不确定度之间的关系,并通过实验着重验证了三次谐波分量将恶化待测基频信号相位噪声的测试精度。     

频谱分析仪——频域测量的最重要工具

频谱分析仪是频域测量的最有效和性能最高的仪器,它测量信号的幅值随频率的变化,这就涉及功率、频率、谐波和噪声。为了测量的方便,频谱分析仪还提供与扫频同步的信号输出,既是测试器也是激励源。随着近年通信和网络的迅速发展,频谱分     

扫频式频谱分析仪测量雷达发射功率误差分析

针对雷达功率测量问题,提出了运用频谱分析仪测量发射功率的方法并对该方法进行了误差分析。首先分析了频域测量发射功率的原理性误差,推导出了理论误差系数并进行了仿真分析,然后通过分析扫频式频谱分析仪的工作原理,列出了影响频谱分析仪实际测量精度的硬件要素,研究了硬件实现中的误差系数,最后得出了该方法测量功率所得结果与实际功率的关系表达式。     

网络无线侦察接收机软件系统的设计和实现

为兼容无线电监测网传输协议(RMTP),实时监测无线电信号并测量其频率、带宽等技术参数,无线侦察接收机软件系统通过网络接收硬件采集的无线电信号,使用经典功率谱估计方法对其进行频谱分析.系统用户界面采用跨平台GUI库CodeBlocks+wxWidgets进行开发,使用二维图形库wxMathPlot开发画图模块,将测量和分析的结果以频谱图的方式展现给用户.分析了系统的基本架构,wxWidgets库的使用方法,经典功率谱估计算法,重点讨论了如何解决网络传输过程中可能遇到的"粘包"问题.     

基于AR模型的载频测量

从现代谱估计出发,利用Yule_Walker方程构造信号的AR模型,从中提取信号的调制载波频率信息。信号的功率谱表示了信号能量的分布。用谱估计法估计出载波频率后,依据频谱对所测频率进行修正,可有效提高载波频率的测量精度。     

一种新的频谱测量方法──实时式频谱分析

一种新的频谱测量方法──实时式频谱分析山东聊城无委监测站杜汐频谱测量即在频域内测量信号的频率分量，以获得信号的多种参数。频率测量的基础是傅里叶变换，它可将一个随时间变化的信号变换成与该信号相关联的频率的函数，因而任意一个时变信号可以分解成不同频率、不...     

常用电磁干扰电平的换算

常用电磁干扰电平的换算张志中近年来，频谱分析仪在电磁干扰测量中使用已很广泛，而频率合成信号发生器在电磁抗扰测量中使用也很广泛。频谱分析仪常用功率电平来显示被测信号的强度，也有用电压电平来显示被测信号大小的。频率合成信号发生器常用功率电平来显示所产生的...     

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.     

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.     

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.     

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.     

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.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.