数字集群中两种常用语音编码算法的比较

对数字集群系统中常用的两种语音编码算法从原理、性能、应用等各方面进行了一系列的分析、比较和讨论。     

Influence of Communication Modalities on Voters' Perceptions of Candidates During Presidential Primary Campaigns

This study examines the relative influence of six communication modalities on voters' perceptions of candidates during contested presidential primary campaigns with less well-known candidates. The investigation panels 113 Democratic and Independent voters of a primary state during the 1992 primary season. Prospective voters were contacted in the "distant phase," that is, before the campaign shifted its full attention to the voters of that state; and in the "localized phase," immediately following an intense campaign leading up to this state's primary election. Results indicate that interpersonal communication dominates all other communication modalities in influencing voters' perceptions of candidates during the distant phase of primaries, and its effect persists into the localized phase. In addition, televised spot advertising, and to a lesser degree, television news, exert the most impact on voters' perceptions during the localized phase of the primary campaign.     

Radio Communication in Tunnels

The attenuation constant of radio waves in tunnels was obtained experimentally and theoretically. According to this study, the tunnel is a transmission channel of high-pass type. It is found that the higher the frequency, the smaller the attenuation constant. The experimental values of attenuation constants are similar to the theoretical values of the the TE/sub 01/ and EH/sub 11/ and modes when the tunnel is regarded as a circular waveguide with the same cross-sectional area as the tunnel. Radio communication using the tunnel was proven to be fully possible in spite of the standing wave effects due to the interference of the propagation modes.     

无线电通信技术对广播电视卫星通信的影响

现阶段科技技术发展速度不断加快,无线电通信技术被广泛应用在各领域的生产、经营、建设、管理环节。在5G时代下,我国无线通信网络更为成熟,信号覆盖率进一步扩大,信号强度也得到了改善。无线电通信技术对广播电视卫星通信行业的发展奠定了技术基础,但也使得卫星通信的稳定性下降。针对此,文中首先分析了无线电通信技术的发展现状,提出了无线电通信技术对广播电视卫星通信技术的影响,探索广播电视卫星通信行业的发展路径,以期为相关工作人员提供理论性帮助。     

Commercial Radio as Communication

Most communication and culture producing institutions in the United States operate more for commercial than for any other motives. This essay examines commercial radio by comparing the day-to-day work routines in that institutional setting with the principles of a theoretical communication model. Commercial radio, of course, does not meet the standards of such a model. By this thought experiment, however, we can illuminate many peculiarities of the conduct of communication by commercial radio, learn more about the application of theoretical models to the evaluation of practicing institutions, and offer assessments of commercial radio that derive from communication theory, rather than from economics, law, politics, or business concerns.     

Radio Communication Scenarios in 5G-Railways

With the rapid development of railways,especially high-speed railways, there is an increasingly urgent demand for new wireless communication system for railways. Taking the mature 5G technology as an opportunity, 5G-railways(5G-R) have been widely regarded as a solution to meet the diversified demands of railway wireless communications.For the design, deployment and improvement of 5GR networks, radio communication scenario classification plays an important role, affecting channel modeling and sy...     

一种基于CR的无线通信侦察体系结构

在分析认知无线电思想的基础上,定义了基于认知无线电的无线通信侦察分析的概念,设计了一种基于认知无线电的无线通信侦察分析的体系结构,为无线通信侦察技术研究提供参考。     

脉冲无线电抗干扰技术

作为一种超宽带扩频信号,脉冲无线电具有优异的抗干扰能力。本文描述了一种利用现有的脉冲技术可以实现的调制方式并对它的抗干扰性能及系统容量进行了理论评估。     

无线电通信中的电磁兼容研究

无线电通信在现实生活中是一种比较普遍的通信方式,其传输速度较快,并且非常方便.但无线电通信同样也存在一些不足,容易受周围环境的干扰,极有可能因周围环境的变化而降低通信质量,如果问题严重,还会停止运行.结合这些问题,通过长期深入研究发现电磁兼容能够有效应对这一缺陷,同时提升运行水平,避免受周围环境所产生的各种影响,确保无...     

Turbo码在无线移动通信中的应用

首先分析了Turbo码的基本编、译码结构与原理，然后探讨了它在无线移动通信系统中的几个具体应用。     

综合业务无线个人通信系统

综合业务无线个人通信系统（ＩＳＲＰＣＳ）将与信息高速公路并存且会使其无限延伸。本文从ＩＳＲＰＣＳ业务需求出发，介绍了该系统设计应着重考虑的一些问题及传输体制，对无线介质可能采用的两种物理层，一种媒体入口控制和数据链作了较为详细的介绍。     

软件无线电技术在卫通终端中的应用

根据软件无线电技术的思想,提出了一种依托通用的可编程硬件平台,以各种软件模块实现不同标准信号通信的多速率、多模式的卫星通信终端的设计。详细讨论了该设备的软、硬件结构设计,并对所涉及的开放式的总线结构、宽带A/D、D/A转换技术、高速数字信号处理技术、功能软件模块化编程设计等关键技术进行了分析。     

多级无线接力系统

介绍了一种新颖的多级无线接力系统。该系统由一个中心站和多个用户站构成。用户站随机地分布在中心站周围。通过用户站的多级接力,中心站可以和每一个用户站进行通信。系统硬件简单,占用频率资源少,成本低。该系统可用作设备监控或信息传输。提出了一种媒介接入方法,并对其性能进行了分析,仿真结果表明了这种方法的有效性。     

水情无线数据网的抗干扰

本文阐述了水情无线数据网中互调干扰、阻塞干扰、邻频道干扰及灵敏度抑制等干扰的产生，提出了抗干扰措施，进而为今后通信网的组建起到建设性的作用。     

软件无线电及其在军事通信中的应用

软件无线电是一种基于可编程能力强的高速数字信号处理DSP，将通用化、模块化、标准化的硬件单元以总线方式连接起来，形成一个通用硬件平台，并利用软件加栽来定义和实现各种无线通信功能的开放式体系结构。软件无线电技术的基本思想是在射频端实现信号的数字化，通过可编程的DSP模块完成对数字信号的各种处理，其核心技术有多频段宽带天线、宽带A／D—D／A转换、高速DSP。在军事通信方面，软件无线电以其灵活性、互通性等特点必将引起各国军用无线电台的根本性变革。     

山区超短波无线电通信链路的设计

叙述了山区超短波无线电通信电路设计的有关技术问题，给出了山峰绕射模式的传输损耗计算方法、绕射位置判断的方法及计算程序流程图，最后通过实例说明此方法的计算精度。     

战术通信无线传播研究

首先简要描述了战术指挥系统通信组成,并对其中的主要通信手段性能和优缺点进行了概括。其次就战术通信站点选择涉及到的相关要素进行了分析,并对通信传输过程中的电波传输损耗做了重点介绍,最后以Egli电波传播模型为例,结合具体的参数,进行了给定条件下的VHF电台传输损耗预测计算。     

空地通信信道的统计特性研究

空地通信信道的主要统计特性包括多径衰落特性、多普勒功率谱和时延功率谱。将空地通信信道视为“双线模型”,推导了用信号平均接收功率和莱斯因子表示的接收信号包络的概率密度函数;假设接收端多径分量的到达角服从某范围内高斯分布,给出了接收信号的多普勒功率谱表达式及其示意图;考虑地球曲率对空地通信的影响,建立了信道的时延模型,并给出了接收信号的时延功率谱。