一种新型的FSK解调系统设计

二进制FSK是数字通信中应用较广的一种调制方式.传统的解调方法在抗噪声性能和运算复杂度之间存在矛盾.文中针对2FSK解调中这个问题,在分析传统方法的基础上提出了一种改进的正交差分解调算法和基于滑动积分的联合定时算法.仿真表明,提出的解调算法具有更好的灵活性,定时算法在性能和实现复杂度上取得了较好的折衷,解调性能良好.     

电磁兼容技术在汽车嵌总线中的应用

用电磁兼容的设计理论分析了汽车中电子设备受电磁干扰的现象及危害性,对汽车嵌总线系统的PCB 板、总线进行了电磁兼容设计,并提出新的滤波电路及连接方法,能解决汽车嵌总线系统的抗干扰问题,达到良好的效果。     

嵌入式linux的底层I2C驱动开发

近年来,ARM linux应用范围越来越普遍,对Linux底层驱动的软硬件开发也成为硬件工程师们开发设备需要重点关注的问题。I2C总线的控制现阶段已经在嵌入式控制系统中应用越来越普及。尽管I2C的硬件体系结构不是特别复杂,然而I2C体系结构在Linux系统中的实现却特别复杂。在Linux下面编写I2C驱动最常使用的方法包括将I2C设备作为一个普通的字符设备来处理以及通过Linux I2C驱动体系结构来实现两种形式。     

基于STM32的航空通信总线切换器设计

ARINC429是目前最常用的一种航空通信总线,它具有简单有效,性能可靠等特性。利用ARINC429总线,飞控系统同各机载设备进行通信,但不同设备上并非都采用ARINC429接口,如卫星接收机采用RS 422总线,且飞控系统ARINC429接口有限。为解决这一问题,提出了基于STM32的航空通信总线切换器设计,方案选取了意法半导体的STM32微控制器,具有高度一体化,低功耗,处理速度快,方便调试与后续开发等优点。     

GaAs光电阴极多信息量测试系统设计

为了优化GaAs光电阴极制备工艺,设计了一个用于GaAs光电阴极制备过程监控的多信息量测试系统.系统采用了先进的现场总线技术,可在线测试阴极加热净化过程中真空度随温度的变化曲线,阴极激活过程中光电流、真空度、Cs源和O源电流的变化曲线,以及阴极激活后的光谱响应曲线.光电流测试精度可达1 nA,光谱响应曲线测量范围在400～1 000 nm.利用该系统对阴极制备过程进行了监测,并给出了测试结果.     

Study on Wusan Granule Anti-tumor Related Target Gene Screened by cDNA Microarray

Wusan Granule, the Ⅲ new drug, is composed of such traditional Chinese medicines as Radix Polygorri Multiflori Praeparata, Radix Noginseng and the like. In 2001, State Drug Administration of China approved clinical trial for Wusan Granule. Wusan Granule possesses the superiority of safety and effectiveness. Its main functions are to supplement Qi and nourish Yin, and to dissipate mass. The animal experiment showing the recipe for Wusan Granule can not only suppress Lewis lung carcinom…     

Resonant excitation of microwave acoustic modes in n-GaAs film

Resonant excitation of coupled space charge-acoustic waves in thin n-GaAs film is theoretically investigated. Possible mechanisms of electroacoustic coupling are piezoeffect and deformation potential. The film is placed onto a substrate i-GaAs without an acoustic contact. The film includes two-dimensional electron gas with a high negative differential conductivity. A possibility of resonant excitation of acoustic modes of the film at the first and the second harmonic of input microwave signal has been demonstrated.     

应用PSice模拟混沌动力学系统的方法

通过具体实例,论 述用PSice求解微分方程的方法,讨论如何用PSpice模拟混沌动力学系统中的有趣的周期分叉现象。     

Coding Schemes Incorporating Soft-Decision DPSK over HF Rayleigh Fading Channels

A soft-decision 8-DPSK modulation format is introducedin a concatenated coding scheme and the performance of the resultingsystem is evaluated over a slow Rayleigh fading HF ionospheric link inthe presence of Additive White Gaussian noise (AWGN). Well-known UngerboeckTCM techniques are used as inner codes and a Reed–Solomon blockcode as outer code. The coded/modulated signal is differentially encodedbefore transmission to combat random phase changes caused by the channel.Soft-decision demodulator's output is used as an input to a modifiedViterbi decoder that calculates the Euclidean distances of the receivedsignal from an 8-PSK constellation adapted to the signal's amplitudevariations. Block interleaving techniques are necessary to randomise longbursts of errors caused by the fading channel. Simulation results showthat significant coding gains are achieved with a minor bandwidth expansionover uncoded, diversity or other coded systems. Finally, theinteresting effects of interleaving on the performance of the proposedsystems are analysed.     

基于CAN总线的码头岸电监控系统实时性分析

随着我国"节能减排"的势在必行,船舶靠港期间使用码头岸电以及岸电供给的智能监控已经成为当前的趋势,并正在大力推广。CAN总线在智能监控领域具有广阔的应用前景,在大型网络监控系统中,监控系统的实时性具有重要的意义。文章分析了CAN总线的实时性问题,针对CAN协议提出了仿真模型,实验测出延时数据,总结比较了当前几种基于TTCAN的算法优化问题。对于开发大型网络监控系统具有一定的现实参考意义。