一种中频数字化正交解调算法分析

对雷达中频接收如何解调出具有回波信号中的同相（I）、正交（Q）分量做了分析,到目前为止,获取数字I/Q分量的算法很多,常见的有低通滤波法和Hilbert法（希尔伯特法）等,现详细的阐述了低通滤波法及其改进实现方法,并给出仿真结果。     

Outage analysis of opportunistic‐based hybrid decode‐amplify‐forward relaying in polar code environment

Outage analysis plays a vital role in wireless systems to determine reliable transmission and effective communication. Incremental hybrid decode‐amplify‐forward (IHDAF) relay offers a way of meeting the challenges of capacity and coverage improvement with great potential in cooperative communication networks. Therefore, opportunistic incremental hybrid relaying must be integrated with coding schemes to achieve full diversity. In this paper, the outage behavior of polar coded and distributed coded cooperative relaying schemes is analyzed. Simulation results show that opportunistic incremental HDAF using polar code offers an outage capacity of 17 b/s/Hz for 4 × 4 multiantenna and 45 b/s/Hz in 8 × 8 multiantenna systems with an outage of 10^?8 and 10^?13, respectively. Moreover, the polar coded opportunistic IHDAF system in 8 × 8 MIMO achieves 2 and 6 dB higher gains compared with amplify‐and‐forward (AF) and decode‐and‐forward (DF) relaying schemes. The closed‐form expression for outage probability has been derived through Marcum‐Q approximations and processed through Monte Carlo simulations.     

采用振荡-放大结构的声光调Q Nd:YAG激光器及光纤传输聚焦系统

研究了一种氪灯抽运的双Nd:YAG棒和声光调制器构成一级振荡加一级放大的声光调QNd:YAG激光器.动态激光平均输出功率最大达到169W,在重复频率1kHz时,测得脉宽70ns,峰值功率达到594kW.用芯径0.6mm的全石英光纤传输激光,并设计了一套聚焦光学系统,实现了大幅面的激光雕刻工作.     

SEP calculations for coherent M‐ary FSK in different fading channels with MRC diversity

In this paper, the authors derive symbol error probability (SEP) expressions for coherent M‐ary frequency shift keying (MFSK) modulation schemes in multipath fading channels. The multipath or small‐scale fading process is assumed to be slow and frequency non‐selective. In addition, the channel is also subjected to the usual degradation caused by the additive white Gaussian noise (AWGN). Different small‐scale fading statistics such as Rayleigh, Rician (Nakagami‐n), Hoyt (Nakagami‐q), and Nakagami‐m have been considered to portray diverse wireless environments. Further, to mitigate fading effects through space diversity, the receiver front‐end is assumed to be equipped with multiple antennas. Independent and identically distributed (IID) as well as uncorrelated signal replicas received through all these antennas are combined with a linear combiner before successive demodulation. As the detection is coherent in nature and thus involves phase estimation, optimum phase‐coherent combining algorithms, such as predetection maximal ratio combining (MRC), may be used without any added complexity to the receiver. In the current text, utilizing the alternate expressions for integer powers (1≤n≤4) of Gaussian Q function, SEP values of coherent MFSK are obtained through moment generating function (MGF) approach for all the fading models (with or without MRC diversity) described above. The derived end expressions are composed of finite range integrals, which can be numerically computed with ease, dispenses with the need of individual expressions for different M, and gives exact values up to M=5. When the constellation size becomes bigger (M≥6), the same SEP expressions provide a quite realistic approximation, much tighter than the bounds found in previous literatures. Error probabilities are graphically displayed for each fading model with different values of constellation size M, diversity order L, and for corresponding fading parameters (K, q, or m). To validate the proposed approximation method extensive Monte‐Carlo simulations were also performed, which show a close match with the analytical results deduced in the paper. Both these theoretical and simulation results offer valuable insight to assess the efficacy of relatively less studied coherent MFSK in the context of the optimum modulation choice in wireless communication. Copyright © 2010 John Wiley & Sons, Ltd.     

旋转波片法测量电光调Q射频波导CO2激光器的内部参数

提出了一种测量电光调 Q射频波导 CO2 激光器内部参数的新方法 ,采用此方法可测量出激光器的小信号增益系数、内部损耗、饱和光强等内部参数 ,并可推广应用到其他种类激光器内部参数的测量。     

基于MMA7260Q的矿震监测系统设计

给出了一种基于三轴加速度传感器MMA7260Q的矿震监测系统设计。该系统由安装在矿井内各巷道和工作面的测量节点和上位机组成,各测量节点和上位机之间通过CAN总线连接,测量节点实现了对矿震信息的现场采集、显示和越限报警,同时通过CAN总线传送到上位机上实现远程监视、同步越限报警和矿震位置定位等功能,适用于矿井发生矿震事故时快速报警和引导撤离。     

光移动回程小蜂窝面临的挑战及解决方案

随着移动宽带服务需求不断增加,需要运营商提供更多的无线接入网络功能。LTE和小蜂窝可提供解决无限覆盖和容量的方案。然而,回程技术在CAPEX方面昂贵,运营成本及传统的解决方案无法提供必要的结合能力和成本效率。文中定义了一个Q带点对多点的回程架构,重点介绍了在构建移动回程和无线接入网络框架中提出的萨拉班德结构,其是一种具有成本效益的网络结构,可提供多千兆能结合在Q带传输一个点对多点毫米波传输技术。此外,文中除了给出网络结构的定义外,还描述了节点的密钥类型,包括萨拉班德具体结构。     

W频段二次谐波I/Q调制混频器的设计

基于自主研发GaAs肖特基二极管（SBD）设计了一款工作于W频段的二次谐波混频器,实现了对射频（RF）信号的I/Q调制。建立了二极管模型,利用电路结构走线长度控制信号流,实现了宽频带内的射频信号混频,并基于此通过HFSS和ADS联合仿真,完成了W频段二次谐波混频器设计。测试结果显示,采用45 GHz信号作为本振信号源,射频80~89 GHz与91~100 GHz的频带范围内变频损耗低于17 dB,最低变频损耗为12 dB;1 dB压缩功率大于11 dBm。仿真结果显示,80~89 GHz与91~100 GHz的镜频抑制效果明显,最好频点镜像抑制达到20 dB。相比于W频段GaAs pHEMT（赝晶型高电子迁移率晶体管）混频器,所设计的GaAs肖特基二极管混频器在较低变频损耗的情况下,具有工艺简单、易实现、高线性度、宽带匹配、高镜像抑制等优点,芯片尺寸仅为1 mm×1 mm。该款W频段混频器达到了目前国内较高水平。     

Multilayer resonators and a bandpass filter fabricated from a novel low-temperature co-fired ceramic

The main objective of this study was to make components from a novel low-loss, low-temperature Co-fired ceramic (LTCC) dielectric, which was also compatible with a high-conductivity silver paste. The multilayer-component fabrication procedure is presented together with a composition for a tape-casting slurry, choice of conductor paste, and LTCC process parameters. A good Q factor, >100 at 2 GHz, using the novel material system has been achieved for λ/2 resonators operating in the frequency range 1.7–3.7 GHz. An excellent frequency response for a 2 GHz bandpass filter has also been achieved; the insertion losses in the passband were less than −2 dB (bandwidth 60 MHz) and the attenuation more than 25 dB in the stopband located 190 MHz higher.     

一种基于统计的多智能体Q学习算法

针对非确定马尔可夫环境下的多智能体系统,提出了一种新的基于统计的多智能体Q学习算法,该算法将统计学习与增强学习有机结合,有效地解决了智能体环境部分感知、信息不确定以及其他智能体行为策略学习的问题,经RoboCup仿真实验证明该算法具有较强的自适应能力和学习效率。