DF4型机车操纵台改造探讨

从铁路行车安全及便利于乘务员操纵机车的角度出发,结合人的习惯性动作,利用人的视觉特征,对DF4型机车操纵台提出尝试性改造探讨,得到了一般性结论。     

DDR2 SDRAM控制器的设计与实现

本文介绍了DDR2 SDRAM的基本特征,并给出了一种DDR2 SDRAM控制器的设计方法,详述了其基本结构和设计思想,并使用Altera公司的FPGA器件Stratix EP2S30F672C3进行了实现和验证,同时给出了设计与实现中应注意的若干问题.     

MSK信号的Turbo同步

Turbo码的提出使系统的性能对同步参数变得极为敏感。文章利用Turbo同步的方法来对Turbo系统进行迭代参数估计,并用插值的方法来减少译码复杂度,最后针对MSK信号给出同步算法。仿真结果表明,在少量增加译码复杂度的情况下,Turbo同步能够使系统获得与严格同步近似的性能。     

投影机用UHP灯性能及寿命延长措施

超高压汞灯(UHP)是液晶投影仪和液晶背投电视的光源,具有光效高、寿命长、光谱好和接近理想的点光源等特点,在DLP,LCD,LCOS等各种液晶投影显示系统中应用广泛。从安全使用的角度介绍了UHP灯芯和灯碗结构特点和设计要求,对UHP灯光谱特征以及延长UHP灯使用寿命的关键措施进行了讨论,并强调了合理的电气工作条件的重要性。     

Characterization and modeling of quantum cascade lasers based on aphoton-assisted tunneling transition

A detailed characterization and modeling of long-wavelength (λ~10 μm) quantum cascade (QC) lasers based on a photon-assisted tunneling transition are presented. In particular, the influence of the finite lifetime of the lower state of the laser transition on the current-voltage and threshold current versus temperature characteristics have been studied both theoretically and experimentally. It is shown that, for our structure, the value of the lower state lifetime can be extracted from the voltage-current curve; the value we found was 2.6 ps. In addition, this model allows to understand the abrupt degradation of the performance of the device for T>150 K. Low temperature (T=10 K) threshold current densities of 1.1 kA/cm² and a tuning range of 85 cm^-1 in pulsed mode are reported. In continuous-wave mode, the emission linewidth of a free-running laser was determined to be 3.9 MHz     

FINE:Future Internet iNnovation Environment

This article introduces FINE(Future Internet iNnovation Environment) project,which is supported by National High-tech R&D Program( 863 Program) of China.     

数字射频存储器在脉冲多普勒雷达噪声干扰中的应用

采用数字射频存储器(DRFM)技术的噪声干扰机,具有瞄频精度高、噪声带宽窄、干扰功率利用率高的特点,可对脉冲多普勒(PD)雷达实施有效干扰。介绍了DRFM干扰机的组成和工作原理。并分析了瞄频误差和寄生信号的产生以及它们对干扰噪声的影响。     

基于SA605和AD9850的接收电路设计及应用

介绍了Philips公司通信专用器件SA605的基本功能及特性,并基于SA605,与当前飞速发展的DDS技术相结合,设计了一种简洁实用的RF信号接收方案.该方案可用于空间信号检测仪接收端.详细阐述了电路实现中的若干问题及其解决方法.     

Performance and Modeling of the MWIR HgCdTe Electron Avalanche Photodiode

The operation of the mid-wave infrared (MWIR) HgCdTe cylindrical electron injection avalanche photodiode (e-APD) is described. The measured gain and excess noise factor are related to the collection region fill factor. A two-dimensional diffusion model calculates the time-dependent response and steady-state pixel point spread function for cylindrical diodes, and predicts bandwidths near 1 GHz for small geometries. A 2 μm diameter spot scan system was developed for point spread function and crosstalk measurements at 80 K. An electron diffusion length of 13.4 μm was extracted from spot scan data. Bandwidth data are shown that indicate bandwidths in excess of 300 MHz for small unit cells geometries. Dark current data, at high gain levels, indicate an effective gain normalized dark density count as low as 1000 counts/μs/cm² at an APD gain of 444. A junction doping profile was determined from capacitance–voltage data. Spectral response data shows a gain-independent characteristic.     

黑龙江移动信令监测系统结构及应用

介绍黑龙江移动公司7号信令集中监测系统的总体结构,及该系统在实际工作中的应用经验.