民航地空数据链中D8PSK信号解调算法研究

甚高频数据链模式2(VDL M2)是下一代民航地空数据链,已在国际民航领域得到应用,其物理层信号采用D8PSK调制模式。面对未来民机装备国产化的需要,地空数据链中D8PSK信号解调算法的研究势在必行。文中以国际民航组织(ICAO)发布的文件为依据,分析了D8PSK信号的特征,研究了信号的解调算法并进行了仿真实现。通过仿真模拟ICAO规定的噪声环境,对比不同解调方法的抗噪性能,明确适用于民航地空通信的D8PSK解调算法。     

TD-SCDMA网络中3G-324M协议栈的研究与实现

本文简要介绍了3G-324M协议栈的主要内容。详细说明了3G-324M协议栈中H．223协议模块以及H．245协议模块的实现方法。描述了MONA（Media Oriented Negotiation Acceleration Procedure）协议的过程。     

K-M模型下的兔血管对Ar~+激光的散射与吸收特性

本文测量了兔动脉和静脉对 Ar+ 激光的反射和透射传输特性。实验采用两积分球系统及波长为476 .5 nm的 Ar+激光器 ,并根据测量数据采用 Kubelka- Munk模型分析了兔动脉和静脉组织对该波长激光的吸收系数、散射系数及总光强 I(x)及前向散射通量 i(x)和后向散射通量 j(x)随厚度的变化情况。结果表明 ,兔动脉和静脉的漫反射率和透射率有明显差别 ;动脉对激光的吸收系数明显较静脉的要小 ;而动脉对激光的散射系数却明显较静脉的要大 ;在动脉和静脉组织中 I(x)及 i(x)和 j(x)随厚度的变化也有明显的区别     

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.     

3G移动可视电话系统设计

介绍了3G移动可视电话的设计架构模式,基于Window CE操作系统,结合VTApp、3G-324M协议栈、音视频设备驱动、RIL和双端口RAM等相关模块,实现了可视电话这一复杂的多媒体应用系统的运行,描述了相关模块的工作原理与设计思路,并通过对呼出流程图加以介绍的方式,对可视电话系统的运行流程加以阐述。     

IGBT驱动模块M57962AL的应用研究

IGBT专用驱动模块M57962AL适于驱动大功率器件，可根据其内部的自保护功能对其应用电路进行安全可靠设计。该模块采用双电源驱动，有过流过压检测电路和保证IGBT可靠通断电路。总之，能够安全地驱动开关、变频器中的大功率IGBT。     

LTE 230MHz技术频谱效率分析

LTE 230MHz电力无线专网是解决电网末端"最后一公里"的主要解决方案。目前230MHz电力无线通信系统有LTE-G 230MHz和IoT-G 230MHz两种技术体制,两种技术的帧结构存在明显差异,文章拟对两种技术体制的频谱效率进行分析。     

激光修补技术在修复薄膜图形缺陷上的应用——薄膜图形缺陷激光修补机

阐述了应用激光修补技术在玻璃基板上去除金属及其化合物薄膜和在玻璃基板上沉积金属薄膜的图形缺陷修补原理与方法;简述了影响薄膜图形缺陷修补质量与效率的关键技术;简单介绍了薄膜图形缺陷激光修补机的系统构成及其技术与性能指标.     

MPEG-DASH与HLS流传输技术的比较分析

选取了具有代表性的HLS企业解决方案,论述新一代流媒体传输标准MPEG-DASH与HLS两种技术的实现原理,比较了两种方案在业务体验、系统效率等方面的技术特性,并从产业链发展与系统演进的角度,分析了运营商部署MPEG-DASH视频业务的可行性和应用前景.     

泛在传感器网络的发展和分析

阐述了未来泛在网络从人与人通信向物与物通信的发展前景,介绍了当前传感器网络行业的应用和典型技术特点,并对传感器网络与电信网融合、形成泛在传感器网络发展过程的阶段和问题进行了分析。