地下低频通信系统语音基带信号的设计

对于矿井等特殊场合,有在地面与地下或者地下多点之间进行无线语音通信的广泛需求,这对地下事故救援、协同作业等有重要意义。为适应地下通信低频率载波对高压缩率数字语音信号的要求,文中设计了一种语音通信设备。设备以麦克风、扬声器作为语音收发端,通过CSP1027对语音信号进行A/D、D/A转换,选用AMBE-1000实现对量化的语音数据进行编码和解码,使用MCU进行系统初始化和语音的传输。实验证明,压缩的波特率低至2400bps时仍可以完成话质清晰、可靠的语音通信,适合作为地下低频通信的语音处理子系统。     

一种基于FPGA的信道多级AGC控制方法

通信系统接收机的信号接收单元一般采用自动增益控制（AGC）,文章针对通信系统接收机设计需具备大动态接收范围的发展需求,提出了一种基于FPGA的信道多级AGC控制方法。该方法主要由大信号抑制控制单元、开环AGC控制单元和闭环AGC控制单元串联组成多级控制系统,实现对通信系统接收机信道大动态范围信号强度的有效AGC控制。试验验证表明：该控制方法实现了对接收机接收信号高控制精度和快速反应时间的可靠控制。该控制方法,具有防止大信号失真、输出信号电压稳定、响应速度快、大动态范围和抗干扰性能较好等优点。     

基于AMBE2000的新型无线同播系统

在无线多通道语音通信中,距离长短使各接收机接收信号的时间不一,同步输出需要精确的延时。介绍一种新型的基于AMBE2000和AD73311的高质量语音同步通信系统的设计与实现。该系统能够在2.0～2.4kb/s的低比特速率产生高话音质量,实现最小步长为1us的输出延时,达到多路同步传输效果。因此,该系统可以广泛应用于软件无线电,多模式电台及多路广播等场合。     

一种电话语音信号光纤接收机的设计

随着FTTH技术的广泛应用,在接入网中进行语音信号的光纤传输越来越普遍。在对PCM（Pulse-code modulation）语音传输系统进行论证的基础上,详细讲述了一种基于PCM的电话语音信号光纤接收机的设计,也指出了最佳接收机的设计要点。该文给出了外接扬声器时的语音输出电路的设计方案。     

基于以太网的串行数字语音通信系统

针对当前广播对讲系统通信带宽受限、音质效果一般和扩展性差等问题,在对现有广播对讲系统进行分析比较的基础上,设计一种基于以太网的串行数字语音通信系统。阐述了系统的结构及软硬件设计,采用内嵌ARM内核的以太网控制器W7500P作为主控芯片,W5500和主控芯片构成双网络接口结构,同时使用语音编解码芯片VS1063实现模拟语音信号与数字音频信号的转换以及MP3格式数字音频信号的编解码功能,从而在保证语音质量的前提下降低语音信号对通信带宽的要求,以实现语音信号的高效传输。该系统连接简单、布线方便、成本低廉。实验测试表明,系统的语音质量、实时性和可靠性均符合现场使用的要求。     

基于DSP的音频信号压缩通信系统的设计与实现

针对数据采集系统中语音传输受传输距离、成本等方面限制的问题,设计了一种低成本的语音信号压缩实时通信系统。采用模块化的方法进行硬件设计,通过将精简的TCP/IP协议移植到以太网控制芯片中来实现局域网通信,在DSP上优化实现了G.723.1语音编码算法,编码后的语音数据通过socket传送到PC端,PC端接收解码并实时播放。实验结果表明在语音质量略有退化的情况下,算法复杂度降低了,系统实现了语音信号远距离的实时传输。     

基于嵌入式的远程通信信号发生器的设计

设计远程通信信号发生器实现通信信号的采集、滤波、检波、放大、调制与接收,提出基于嵌入式技术的远程通信信号发生器设计方案。信号发生器主要包括了通信基阵模块、收发转换电路模块、通信信号滤波及检波电路模块、信号放大处理模块、信号调制解调模块以及接收机设计等。采用嵌入式控制器PXI-8155对通信信号发生器的各模块进行串口、并口及GPIB接口的总线设计,实现远程通信信号发生器的嵌入式集成总线优化设计。对信号发生器进行通信信号传输处理分析,实验结果表明,该远程通信信号发生器能有效提高信号的稳定准确传输能力,降低通信信号传输的误比特率。     

基于CNN的雷达嵌入式通信接收技术研究

雷达嵌入式通信(Radar-embedded Communication, REC)是一种在雷达后向散射回波中嵌入通信信号的新型隐蔽通信手段。为了进一步提高REC系统中通信接收机的接收性能,提出了一种基于卷积神经网络(Convolutional Neural Networks, CNN)的REC合作接收机结构——CNN接收机,给出了CNN接收机的设计原理及详细结构,并对CNN接收机的接收性能进行了仿真和分析。结果表明,相较于传统REC合作接收机,CNN接收机具有更优的接收性能,REC系统可以使用功率更低的通信信号来保证相同的通信可靠性,以此来增加抗截获性能。     

语音信号增强系统设计与仿真

在信号处理中语音增强是一个重要分支,针对语音信号不得不在噪声和干扰环境下通信的现状,采用自适应滤波算法设计了语音信号噪声和干扰抑制系统,首先对LMS算法进行了推导,并且对噪声和干扰环境下的自适应滤波器性能进行了仿真分析,仿真结果表明:该设计抑制干扰和噪声的性能较好,对语音信号的增强明显,为该系统在硬件上实现提供了理论基础。     

通信机音频放大器

本电路边缘陡削的语音滤波器、集成功率放大器和电源等三部分组成,可为8Ω扬声器提供1.2W 输出功率。在接收机受到干扰而使音频输出信号产生严重失真时,它可以提高话音信号的可懂度,适合用作通信机和远距离接收机的外接音频放大器。如图1所示,电位器 P1是本放大器的灵敏度调节器。当输入端接到接收机的耳机或外接扬声器插座等强信号输出端时,可以调节 P1适当降低本放大器的灵敏度。因此,本放大器可直接用于通信接收机而无需对接收机作任何改     

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.     

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     

Call for Papers—Feature Topic,Vol.12,No.7,2015

正Information Centric Networking Information-Centric Networking(ICN) is an emerging direction in Future Internet architecture research,gaining significant tractions among academia and industry.Aiming to replace the conventional host-to-host communication model by a data-centric model,ICN treats data content as the first