一种中频数字化接收机中的数字信号处理技术

数字化接收机的硬件结构和功能相对独立,这样就可以基于相对通用的硬件平台,通过软件编程对中频频率、系统频带、调制方式等进行设置,最终实现灵活的多功能、多体制通信接收机.通过对软件升级可以不断扩展和完善接收机的功能.本文系统阐述了中频数字化接收机中的数字信号处理技术.首先从模拟通道人手,介绍了超外差式模拟通道组织方案.接下来重点论述了带通采样理论、数字下变频技术、基带数字解调技术、自动增益控制(AGC)原理.     

一种中频数字化接收机中的数字信号处理技术

数字化接收机的硬件结构和功能相对独立,这样就可以基于相对通用的硬件平台,通过软件编程对中频频率、系统频带、调制方式等进行设置,最终实现灵活的多功能、多体制通信接收机。通过对软件升级可以不断扩展和完善接收机的功能。本文系统阐述了中频数字化接收机中的数字信号处理技术。首先从模拟通道入手,介绍了超外差式模拟通道组织方案。接下来重点论述了带通采样理论、数字下变频技术、基带数字解调技术、自动增益控制（AGC）原理。     

数字下变频器HSP50214B在中频数字接收机中的应用

数字下变频器(DDC)对侦察接收机的软件化设计至关重要,给出中频数字接收机数字下变频电路实例,实现了数字侦察接收机对多种调制样式信号的高性能处理.展示了数字下变频器HSP50214B在中频数字接收机中的灵活应用.     

适用于DBF的多通道中频宽带数字接收机设计

介绍了一种适用于DBF的8通道中频宽带数字接收机的设计方案。首先介绍了主要芯片的设计选择和设计原理,并就DBF多通道中频宽带数字接收机的关键指标进行了试验测试,给出测试数据。结果证明了该方案很好地解决了多通道接收机的幅相一致性和稳定性问题。     

HSP50216在数字中频接收机中的应用

对于数字下变频器HSP50216的功能进行了介绍，对于数字中频接收机的基本组成和利用HSP50216进行数字中频接收机设计的方法进行了研究，并且利用它构建了4通道全数字的中频接收机系统。     

多通道数字接收机的设计与实现

为了解决传统模拟中频接收机相位分辨率低等缺点,提出一种基于软件无线电的中频数字接收机技术。针对雷达信号的特点提出了脉宽匹配滤波器的设计方法。采用基于多相滤波的正交变换理论,以及基于脉宽匹配的数字滤波器方法完成了一种五通道中频数字接收机的设计。接收机利用五路高速A/D变换器对输入的模拟信号进行采样,然后将采样数据送入FPGA进行处理,最终完成了每两路信号相位差的提取。实验结果表明系统具有成本低、精度高、结构简单等特点,而且具有一定的工程应用价值。     

机场天气雷达双通道数字中频处理系统的实现

机场天气雷达要求能够从复杂的天气环境中识别不同的天气状况以保障航空飞行安全,其接收机大动态以及抗噪性能设计对雷达至关重要。在分析模数转换器（ADC）对雷达中频接收机动态范围制约的基础上,根据中频带通采样和数字下变频的原理,实现了基于现场可编程门阵列的双通道ADC采样数字中频处理系统,并给出了系统的设计原理、方法以及测试结果。通过对双通道ADC采样的数字中频处理系统的实现,能够很好地提高天气雷达接收机的动态范围,并应用于机场多普勒天气雷达数字中频接收机。     

一种多模式合成孔径雷达数字接收机

针对一种多模式极化合成孔径雷达（SAR）,给出了中频数字接收机工作参数选择,混频滤波方法,实现了三种带宽信号的数字正交解调。通过分析同相、正交通道误差对正交解调性能的影响,确定了滤波器最佳设计准则。最后给出了基于FPGA的实现结构,仿真试验结果表明中频数字接收机性能比一般模拟接收机有显著提高。     

通信接收机测试、信号处理仿真系统

现代通信领域,一般采用中频输出经高速A/D采样和数字下变频后直接进行数字信号处理.通信接收机测试、信号处理仿真系统可分别对通信接收前端和信号处理进行测试,直接采集接收机中频模拟输出信号,并使用相应接收机测试软件及系统评估接收机的性能,如:接收机动态范围、增益曲线、幅频与相频、通道间相位一致性等.通信接收机测试系统组成如图1所示,实际采集的数据用于信号处理算法仿真,将数据送至信号处理机,测试信号处理机性能,从而加快通信系统研发和调试进程.     

扩频系统多通道相位差测量技术

论述了扩频无线电信号侦收和测向等应用领域中,在多通道天线和接收机后端采用数字处理手段,在低信噪比下实现多通道相位差精确提取的方法.阐述了多通道相位差提取的基本工程模型、中频信号采样处理方法、普通ASK调制信号的相位差提取方法,以及BPSK调制的扩频信号的相位差提取方法,给出了基于MATLAB7.0.1平台的仿真图形和结果.该技术已在工程中成功实现.     

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.     

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.     

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.     

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.     

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