MPSK信号循环谱检测与码元速率估计改进算法

利用循环谱理论对MPSK信号进行检测和参数估计,分析了其循环谱包络特征;在有限数据下,为实现更低信噪比情况下MPSK信号的检测与码元速率估计,提出一种改进算法。该算法基于数据分段处理和重叠保留,通过在非零循环频率上一维谱峰搜索实现信号检测与码元速率估计,能够有效地抑制噪声的影响,避免多维搜索,计算量小。分析了算法性能,给出了算法实现的具体步骤,并进行了计算机仿真。仿真结果证明了所提算法的有效性。     

基于余弦窗变换的MPSK和QAM信号的码速率估计

电子对抗的实际应用中为了完成信号的分类、解调任务，需要精确估计截获信号的码速率。针对数字通信中常见的MPSK、QAM信号，提出了一种基于余弦窗变换的码速率估计新算法。利用余弦窗变换确定信号相位跳变位置，进而利用谱分析精确估计码速率。理论分析证明了算法的有效性。仿真试验表明，当信噪比大于5dB时算法是有效的，且优于采用小波变换的方法。     

基于谱相关的直扩信号载频及伪码速率估计技术

将谱相关理论应用到直接序列扩频信号的关键参数估计中，针对BPSK调制的直扩信号，分析了其谱相关密度函数的特征，提出了基于集平均的谱相关估计算法。该算法在非零循环频率上搜索特征谱线，从而在较低信噪比下完成对直扩信号载频和PN码速率的估计。最后通过仿真验证了该算法的性能。     

谱相关理论用于直接序列扩谱信号的检测与估计

本文论述了谱相关理论在直接序列扩谱信号的检测与估计中的应用，提出了利用谱相关函数法与集平均算法相结合的方法来实现对低信噪比直接序列扩谱信号的检测及其载频与伪码速率的估计，并利用相关处理方法来估计的伪码周期，信息码序列及伪码序列，通过计算机模拟证实了该方法的有效性。     

时分数据调制偏移载波信号的多参数盲估计

针对时分数据调制二进制偏移载波(TDDM-BOC)信号副载波速率、伪码速率以及载频等参数盲估计问题,该文提出一种基于频域累积的循环自相关算法。首先在接收端对TDDM-BOC信号求循环自相关函数,再在频域累积,通过检测不同切片上的谱峰间隔,可以同时估计以上多个参数。仿真实验证明了改进型的循环自相关算法能在低信噪比下达到较为精确的估计性能,这为我国北斗导航接收机的研发提供了一定的理论参考。     

多径环境下的直扩信号伪码周期估计

针对低信噪比条件下多径直接序列扩频(直扩)信号伪码周期估计的难题,拓展了先前提出的单径环境下基于信号功率谱二次处理的方法,提出了在低信噪比条件下多径环境中直扩信号的伪码周期估计的二次谱算法.该算法首先对多径直扩信号求取功率谱,然后将所得到的功率谱作为一输入信号求其第二次功率谱,所得二次功率谱将在伪码周期整数倍处出现代表信号存在的尖峰脉冲,通过对这些尖峰脉冲闻的距离进行检测就可以获得多径直扩信号伪码周期参数的检测估计.理论分析和计算机仿真结果表明:该算法可以有效地估计出多径环境下直扩信号的伪码周期,且估计性能和多径环境密切相关.     

MPSK信号载频盲估计

研究了相位编码信号（MPSK）的载频盲估计算法。在没有接收信号先验知识的情况下，首先对MPSK信号载频进行粗估计，然后进行相关运算把信号，接着估计码速率，得到载频和码速率的估计值，就把载频估计问题转化为频偏估计问题。利用基带MPSK信号的相位函数是分段线性函数且每一段直线的斜率均正比于频偏的性质，对接收信号的相位函数进行处理，把分段直线变成一条直线，最后运用最小二乘拟合法得到直线的斜率从而得到频偏估计。仿真表明本算法在没有先验知识的情况下可以对MPSK信号载频进行精确估计。     

一种多MPSK信号符号速率盲估计算法

针对多个多阶相移键控信号(MPSK)符号速率快速高精度估计问题,在分析MPSK信号特征和连续小波原理的基础上,提出了一种基于小波变换的多MPSK符号速率盲估计算法,利用固定尺度的小波变换将多个信号的相位跳变信息映射为其小波变换的幅度跳变信息,进而完成对符号速率的盲估计。仿真结果表明,算法具有多信号处理能力,对载频估计误差不敏感,在低信噪比下具有良好的测量性能以及一定的实时处理能力。     

基于循环自相关集平均的DS信号参数盲估计

在循环平稳理论基础上,以DS/BPSK信号为例,分析其循环自相关函数特征,提出一种基于循环自相关集平均的参数盲估计算法。该算法在非零循环频率上搜索特征谱线,从而在较低信噪比下完成对直扩信号载频和PN码速率的估计。通过算法仿真,证明该算法能够有效提高参数估计的信噪比容限。     

一种基于特定Duffing振子的MPSK信号调制识别算法

该文利用混沌振子对噪声处理的优势,提出一种在低信噪比条件下基于混沌理论的调制识别方案,给出了对MPSK信号进行调制识别的原理与方法,并设计了新的Duffing振子模型用以提升识别效果。该算法仅仅利用载波频率的先验信息,无需对相偏、码速率、噪声功率等参数进行估计。仿真实验表明信噪比在-5 dB时,3种MPSK信号的正确识别概率在95%以上,证明了该文算法的有效性。     

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.     

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.     

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.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

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.     

Call for Papers

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