参量换能器收发电路设计

介绍了超声波参量换能器的工作原理,设计了一种声学参量换能器结构、超声波发射电路和声波接收电路。发射电路由正弦信号产生电路、功率放大电路和补偿电路等组成,声波接收电路由前置放大电路和带通滤波电路组成,并利用NI公司的6024E数据采集卡进行数据采集。理论分析表明,当原波信号为87 kHz时,利用该收发电路可以较好地实现参量阵差频信号的发射与接收。     

多探头双频超声波接收电路设计

该文创新设计了一种多个双频超声波探头的超声波接收电路,适用于海洋鱼类资源探测等需要用到多个超声波探头的场合。该接收电路由前级放大电路,开关切换电路,带通滤波电路和后级放大电路组成。DSPIC单片机负责控制,接收电路多对一分时切换。采用了收发隔离电路,使得超声波探头可以工作在收发一体的工作方式,有效的节约了电路和探头的成本。     

数字时分系统设计

提出了一个时分复用传输系统收发两端的结构原理图,介绍了核心器件DSP和 CPLD,设计了一个基于特殊帧结构的时分复用传输系统来传输视频信号、语音信号和数据信号.整个系统由发射、接收2块电路单元和光纤传输单元组成,阐述了系统的工作原理.     

基于ARM和CPLD的无线风速仪设计

分析了在平面三角形阵列中利用超声波时差法测量风速风向的基本原理,设计了基于ARM和CPLD微处理器的无线风速仪。给出了以LPC1768和EPM240T100C5芯片为核心的超声波无线风速仪的设计实现方法。重点阐述了超声波驱动电路、信号调理电路、无线收发模块以及系统软件的设计。实验结果表明,该系统可以精确测量风速与风向,且工作可靠稳定。     

JTS-4型超声波探伤仪

上海超声波仪器厂试制成功的JTS-4型超声波探伤仪是一种A型脉冲反射式超声波探伤仪,适用于金属工件无损探伤。该仪器采用矩形大屏幕大偏转角示波管。电路全部由晶体管和集成电路组成;采用积木式结构和插件装置。它可配用八种不同规格的探     

用于超声波测距的发射及接收电路设计

在具有超声波测距功能的仪器设备中,用于驱动超声波发射及接收的电路设计种类较多。从产品的成本及体积考虑,多数采用集收发于一体的超声波换能器,采用这种设计的产品,其款式和价格都具有一定的优势。但在电路设计方面需要更高的要求,在发射时发射电路不能破坏接收电路,接受电路也不能影响发射;在接收信号时,由于信号较弱,应尽量减少由发射电路所造成的对信号的损耗。我们所设计的电路如附图所示,试验效果良好。     

具有语音播报功能的超声波液位测量系统设计

超声波测距相比于其它测距方法,具有非接触、高精度、价格低、使用方便等优越性。针对实际应用的需要,设计了一种以单片机为主控芯片的具有语音实时播报和无线收发功能的超声波液位计系统。首先介绍了超声波测距原理,然后设计了系统硬件、系统方案及各个电路模块,包括发射电路、接收电路、语音播报电路、无线收发电路等,其次设计了系统软件程序。最后进行了系统测试。测试结果表明在加入温度补偿后测量精度可以达到0.8%,语音播报和无线收发稳定。     

测量总论

Y98-61452-282 9915798评估电机定子线圈适应三相短路绝缘能力的动态弯曲测试法=Dynamic bending tests:a method to evaluatethe ability of stator coil insulation to accommodate 3phase short circuits[会,英]/Christodoulou,A.＆ Wed-dleton.D.//1998 IEEE International Symposium onElectrical Insulation,Vol 1.—282～287(AG)9915799新颖的便携式数字化超声波探伤仪[刊]/王敬东//电子技术应用.—1999,25(5).—28～29(D)超声波探伤仪的数字化是超声波探伤发展的迫切需要。文中结合实际研制开发工作,介绍了数字化超声波探伤仪的软硬件设计方案、系统组成、功能特点,并对探伤信号的高速采集技术进行了分析.同时给出了适合应用的解决方案。参3     

超声波驻车暨倒车雷达系统研制

主要介绍超声波驻车暨倒车雷达的工作原理及其电路设计.系统由超声波有源传感器、PIC16F77单片机、车速信号和倒车档信号输入电路、超声波发射电路、超声波接收电路、显示和报警电路组成.该倒车雷达具有抗干扰性能好、反应速度快、性能价格比高等特点,完全满足于车辆对障碍物测距,现已经在某国内车厂实现了批量生产.     

一种小型高频无线收发系统的模块化设计

介绍了一种采用高集成度收/发芯片及编/解码芯片构成的高频无线收发系统的模块化设计方案.分析了设计高频无线收发模块的思路,采用最新的硬件编/解码电路实现了对载频信号的直接调制与解调,采用高标准、高品质的高频传输回路和编解码芯片,运用固定工作模式,使所有RF和IF均在电路中自动完成,大大简化了用于产生FM信号的控制逻辑,有效地提高了收发系统的集成度.     

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