基于可配置DSP的VoIP语音编解码器设计

VoIP是利用IP网络实现语音通信的一种先进的通信方法,语音压缩编解码技术是VoIP的关键技术之一,是VoIP网关及IP话机中的重要组成部分.叙述了以可配置VLIW结构的DSP来实现VoIP语音压缩编解码器的设计过程,其中包括VoIP编解码器的相关算法设计和DSP核配置生成,最后进行了FPGA验证,表明设计的VoIP语音压缩编解码器的性能完全能满足VoIP中实时、高效的全双工语音通信应用的需求.     

基于TMS320F2812的多通道实时语音编解码

介绍了自适应多码率语音编解码算法及其基于TMS320F2812定点DSP芯片的实现方案。利用TMS320F2812芯片集成的多路ADC和PWM,对方案进行了多通道的扩展。分析了在DSP芯片上实现实时语音编解码及多通道扩展的关键技术。最后分析了此多通道实时语音编解码方案所需的存储空间和计算复杂度。     

基于XDAIS标准G.729A算法的VoIP语音网关设计

针对VoIP交换机语音网关的需求,实现了基于XDAIS标准的G.729A算法。结合TI DSP处理器C55x的特点对算法进行优化,实现单片TMS320VC5510中12路语音编解码,在此基础上完成了支持96路话音的VoIP语音网关的设计,并已成功应用到多种型号的军用语音交换机中。     

低成本远程语音监控系统的设计

介绍了一种运用DSP(数字信号处理器)控制的基于以太网传输的低成本高音质语音监控系统,该系统主要由语音采集模块和语音传输模块组成.语音采集模块由TI公司的16位高速DSP芯片TMS320VC5402和语音处理芯片MC14LC5480组成,语音传输模块由DSP控制以太网控制器8019通过双绞线连接到远端PC来完成,能在远端PC上控制监控的启停及现场回放.文中给出了硬件设计结构和软件设计流程.     

ITU-T G.729算法及其实时实现

在介绍G.729编解码算法原理和TMS320C541定点DSP芯片的基础上,详细讨论了G.729编解码算法在TMS320C541上实时实现的关键技术。实验结果表明,单片TMS320C541能够实时实现G.729语音编解码算法。     

Filter Graph技术在语音处理系统中的应用

随着Internet的普及和VoIP技术的发展,语音媒体流的处理显得越来越重要.因此,如何将语音流媒体的处理变得简单而高效逐渐成为人们研究的重点问题.本文以ISDN媒体网关为例,探讨如何使用Fiter Graph技术构建语音处理模块,完成复杂多变的语音信号的处理.在本人开发的ISDN语音媒体网关中,应用Filter Graph技术,使我们在短期内实现了抖动消除、语音压扩、RTP打包等复杂的功能,而且编制的语音媒体处理软件易于维护和升级.     

基于DSP的语音录放系统的设计

以数字信号处理器(DSP)TMS320VC5402为核心处理器,设计了一个语音录放系统。该系统采用的数字编解码模块是由TLC320AD50芯片完成的,采用音频线,通过DSP内部的多通道缓冲串口(MCBSP)将电脑中的音频信号送到DSP中,DSP再将音频信号进行处理,通过TLC320AD50输出。最后,音频信号从耳机或外置喇叭传出。     

多媒体通信中的语音编码及其DSP实现

介绍了各种语音编码方法、讨论了多媒体通信中的语音编码，详细介绍了G．729的编解码方法及如何用DSP芯片来实现语音编码。     

基于ARM和DSP的VoIP网关的设计与实现

文章介绍了基于ARM和DSP的VoIP网关的软硬件设计.其中硬件主要由基于ARM内核的微处理器S3C44B0子系统和基于LSI403LP芯片的DSP子系统以及电话接口模块构成.软件设计主要负责控制SIP核心协议栈oSIP、RTP/RTCP核心协议栈ccRTP的正常运转,控制外围DSP芯片工作.测试证明,文章所设计的VoIP网关能够实现网关的主要功能,具有成本低廉、应用灵活、可扩展性好的特点.     

可堆叠VoIP语音板卡的固件程序设计

本文提出了基于口可堆叠式的VoIP通信应用系统的系统架构,重点介绍了面向IP可堆叠式的VoIP语音板卡的固件程序设计.每块VoIP语音板卡支持8路语音,通过自定义的通信协议可使不同的VoIP语音板卡独立地通过IP互联,实现基于IP可堆叠.自定义通信协议实现了VoIP语音板卡中芯片内部通道之间、VoIP语音板卡上芯片之间、不同VoIP语音板卡之间,以及VoIP语音板卡与管理PC间的通信.VoIP语音板卡控制软件以内核模块方式运行,并在内核模块方式下由VINETIC-2CPE语音芯片中断服务程序激活回调函数,提高了实时性.     

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