半导体激光器高速驱动源

本文介绍满足ＤＦＢ激光器高速特性测试要求的一种半导体激光器高速驱动源的设计要点、测试结果和使用情况。     

多道脉冲幅度分析器改进研究

分析了多道脉冲幅度分析器忙时间的形成特点,设计出来一套能减小系统忙时间的方案,从而大大地减少由于忙时间造成的脉冲漏计数。同时分析了改进后系统和实际测量时存在误差的主要因素;该方案具有实现有成本小,方便灵活等优点。     

Broadcasting by satellites

As a result of recent advances in signal processing technology and standards for video compression systems there has been a dramatic increase in interest in commercial applications. This paper reviews the current broadcasting situation from a number of viewpoints relevant to the future development of the available technologies. After a review of the context, which includes alternative new broadcasting technologies as well as alternative media capable of competing with satellite, digital technology is given a wide ranging assessment with particular attention paid to the direct broadcasting to the home by satellite application currently receiving considerable attention world-wide. The possible system architectures and subsystem design features are highlighted with the European Baseline Satellite Broadcasting specification developed by the European Digital Video Broadcasting Project gaining special attention. For completeness a brief review of the digital audio broadcasting system (DAB) is also given. In addition to the applications for direct broadcasting, applications in the professional domain for distributing television signals from studios to terrestrial transmitters, satellite up-link sites or cable heads or for satellite news gathering (SNG) are examined. Features of existing commercially available hardware to support these services are described briefly.     

利用激光脉冲飞行时间测量货车车厢体积

介绍了利用激光脉冲飞行时间测距技术测量货车车厢体积的技术方案。通过该方法,可以准确地把2~6轴货车的车厢体积从货车体积中分离出来并计算得到。通过所采用的三阶高度矩算法此算法来源于数字图像处理边缘检测中的三阶灰度矩,对于各种车轴的货车,都可以精确地去除车头和车底货架并计算出车厢体积,而且针对台阶状的6轴车,台阶点的位置和车厢体积也能准确地获得。此外,所介绍的货车截面数据翻摺拼合技术激光扫描测距仪的数量可以减少到2台。该测试方式已应用到货车厢体积测量的实际工程中,通过大量实际货车数据验证,它能很好地计算出货车厢的体积。     

LFM-BC脉压雷达信号处理系统的仿真

运用数字信号处理理论和Matlab软件研究了具有线性调频-二相编码（LFM-BC）信号体制脉冲压缩雷达的信号处理仿真,提出了一个仿真模型,该模型能够仿真雷达信号、系统噪声与杂波和LFM-BC脉压雷达系统中信号的动态处理过程,具有很好的多普勒性能。     

一个新的IEC61000-4-2标准ESD电流解析表达式

分析了两个ESD标准电流波形表达式,并提出一个新的基于脉冲函数来描述ESD标准电流的解析表达式,该表达式符合最新的标准IEC61000-4-2,在零时刻的电流及其微分部为0,且波形与实际测量波形基本吻合。     

Downlink multiple access schemes for transmitted reference pulse cluster UWB systems

Transmitted reference pulse cluster (TRPC) signaling was recently proposed for low data rate ultra‐wideband communications. Compared with the conventional transmitted reference (TR), TRPC has a more compact and uniform spacing for the reference and data pulses and therefore solves the implementation problem posed by the long delay line requirement in the conventional TR. In this paper, downlink multiple access issue is further investigated for TRPC systems. According to the TRPC signaling structure, both code division multiple access (CDMA) and time division multiple access (TDMA) methods are discussed. Theoretical analysis and simulation results show that TDMA outperforms CDMA in both bit error rate performance and throughput. Copyright © 2010 John Wiley & Sons, Ltd.     

Side-lobeless far-field spectrum of a short pulse from a circular aperture with Gaussian form of transmittance

The spectrum change of a Gaussian pulse in the far field is studied with the Fresnel diffraction integral when it is incident on an aperture with Gaussian form transmittance. It is found that the side-lobes of the diffracted spectral intensity, which exist in a normal circular aperture with unit transmittance, can be eliminated completely under such a condition. Also, the red shift and blue shift of the spectral intensity maximum of the incident pulse are presented.     

一种适应复杂电磁环境的重频跟踪方法

针对现代电子战日益复杂的电磁环境以及不断涌现的新体制雷达,本文采用脉冲预测的方法对指定的雷达信号进行重频跟踪。由于脉冲预测的特征规律与目标雷达重复周期精确一致,重频跟踪器解决了如何在复杂电磁环境下进行实时信号跟踪的问题,并且能够适应多种不同体制的雷达信号。     

All-digital controlled boost DC–DC converter with all-digital DLL-based calibration

Traditional digital controls mostly use digital–analog converters to convert input and output voltages into digital coding to achieve control. This paper proposes the use of two digital ramps with two different frequencies to replace a digital–analog converter. This approach can produce seven bit resolution for the DPMW signal. In addition, we use an all-digital DLL phase correction concept to further enhance the resolution of the DPWM signal by an additional three bits, resulting in 10-bit DPWM signal resolution. The proposed circuit uses 0.35 μm CMOS processes, with a core area of 0.987 mm², a system switching frequency of 500 KHz, an input voltage range of 3.3–4.2 V, and an output voltage range of 5 V. Output voltage measurement accuracy reaches 99%, while the system reaches efficiency of 91% with output loads of up to 500 mA.