Using on-channel repeater to improve reception in DTV broadcasting service area

The paper presents the results of a series of tests performed by the Communications Research Centre Canada (CRC), to investigate the possibility of improving reception, by using an on-channel repeater (OCR), in areas already covered by an 8-VSB digital television transmitter. The results are then compared with those obtained at the same test locations using DVB-T transmission at various bit rates to study the impact of OCR versus reduced bit rate transmission. The results should show under which conditions it might be possible to use an OCR, instead of reducing the bit rate, to improve reception in parts of the coverage area of a main transmitter.     

Analyzing the FCC's DTV spectral emission mask and potentialdegradation to adjacent channels due to antenna pattern differences

The FCC DTV spectral emission mask is analyzed with an NTSC subjective noise weighting function to determine the desired NTSC to undesired adjacent channel DTV signal ratio at the threshold of visibility of interference. Factors which alter the NTSC/DTV adjacent channel signal ratio at various receiving locations within the NTSC service are examined: (1) the azimuth patterns of the NTSC and DTV broadcast antennas; (2) the elevation patterns of the NTSC and DTV broadcast antennas; and (3) the centers of radiation of the NTSC and DTV broadcast antennas. These factors together with the NTSC/DTV authorized power ratio may make the DTV spillover spectrum exceed acceptable picture (and sound) interference levels even though compliance with the FCC DTV spectral emission mask is met. Spectral shaping solutions are examined by use of the NTSC subjective noise weighting     

关于CDMA直放站干扰的实例分析

干扰问题一直是移动通信网络优化的重点问题，随着新兴移动网络运营商的加盟，频谱资源日趋紧张，各种潜在干扰源正以惊人的速度不断产生。直放站作为无线网络覆盖的重要产品，主要应用于移动通信网络中。它在中继无线信号、延伸无线覆盖区、覆盖特殊地形、调配业务、消除盲区、优化网络方面起了很大作用，但同时对周围基站（特别是异构系统）产生了较多的干扰。如果直放站设置使用不合理，将对移动通信网络造成严重干扰。我们在近两年实际工作中对移动通信网的干扰排查结果表明，直放站所造成的干扰最多，影响最为严重。所以研究减少相关干扰的方法、采取相应措施十分必要。下面笔者结合实例对直放站干扰进行简要的分析。     

数字电视显示器产品测试统计分析

介绍了数字电视显示器标准颁布后开展的产品检测认证情况，对检测结果进行了统计分析，列举了检测中所发现的一些共性问题，提出了标准颁布实施后，企业应该重视的关键问题，供有关人员在贯彻标准中参考。     

数字电视条件接收系统中的安全性分析

概述了数字电视条件接收系统的基本原理，针对条件接收系统中几个主要环节的安全性问题逐一作了论述，对目前这一行业国内外厂商的发展状况作了一个简单的总结。     

Echo analysis of side-mounted DTV broadcast antenna azimuthpatterns

Azimuth pattern analysis of a side-mounted antenna is made keeping reflections separate from the main radiated signal. Each reflection is characterized by a reflection coefficient and path difference in wavelengths at a distant receiving summing point. At each azimuth, the reflections are expressed as echoes accompanying a modulated VSB data pulse. The corresponding receiver equalizer tap weights are determined from which the DTV receiver threshold impact is calculated. Measurements of a side-mounted antenna using an azimuth fly-around technique are compared to the calculated results for specific azimuth directions. It is concluded that the DTV performance degradation caused by close-in reflections from adjacent tower members may be predicted by calculation and that the degradation is small     

An analysis of interconnect delay minimization by low-voltage repeater insertion

The effect of voltage-scaling on interconnect delay minimization by CMOS-repeater insertion is analyzed. Analytical models are developed to calculate the optimum number of repeaters as function of CMOS supply voltage. The analytically obtained results are in good agreement with SPICE extracted results. Analysis shows that voltage-scaling decreases power dissipation and the optimum number of repeaters required for delay minimization in long interconnects. Both resistive and inductive interconnects have been considered. At highly scaled voltages, the inductive interconnect has the advantage of lower power-delay product. It is also seen that voltage-scaling affects delay improvement due to repeater insertion.     

数字电视的测量

本文论述了加强数字电视信号测量的必要性，简要介绍了数字电视测量与模拟电视测量的区别，概要介绍了数字电视测量的特点和基本方法，并结合作者的工作实际对数字电视的测量尤其是MPEG－2／DVB码流和串行数字分量信号的测量进行了重点介绍，提出了立足现有条件进行数字电视信号测量的可行方法，并提出了进一步改进的建议。     

DTV standards and transition: A comparative policy analysis

China recently has emerged as a serious player in setting ICT standards, as evidenced by its presence in major conferences on standardization with the International Telecommunications Union. While the ATSC standard contributed to the successful completion of the DTV transition in the US, China’s home-grown DTV standard bears little, to date, on its relative success in converting one third of its cable households to digital service. In light of these differing outcomes, this paper identifies and compares the strategies behind the quest for national DTV standards by retracing the key policy initiatives in China and the US. Our analysis suggests that protectionist impulses shaping distinct standards for the US (Grand Alliance), China, and other regions dampen prospects for a global standard in DTV. However, the US has been more successful at maintaining the kind of balance between industry and governmental policy that is critical to maintaining technological innovation and a competitive marketplace.     

语言复读机的测试

1 引言。复读机通过微机控制的语音芯片，把磁带放音或学习者的读音信号经内／外置传声器将信号存储并整合，由CPU控制，学习者可根据学习要求以多种形式重放，无需反复倒带就可随意反复播放，跟读对比。只要原声带是个好老师，学习者就能随时随地得到良好的外语听力和口语训练，因此受到各行各业学习外语人士特别是青少年的喜爱，也造就了新的市场。     

数字电视传输技术

1数字电视有三种传输网络数字电视传输网络主要指地面、有线和卫星三大数字电视广播传输网络。地面数字电视广播网络通过电视台制高点天线发射无线电波,覆盖电视用户,用户通过接收天线和电视机收看电视节目。这是数字电视广播最基本的传输网络形式,除了娱乐、学习等公益功能之外,其普遍性、可控性和抗毁性还被视为国家安全设施,使之成为紧急情况下动员国民最直接最可靠的政府喉舌。     

R&S数字电视发射机

本文介绍了德国 Rohde & Schwarz公司 NV70 81型数字电视发射机的特性、基本原理和操作设置 ,同时对发射机的校准和调试进行了初步探讨     

数字电视标准的制定及利用卫星传送的前景

当前 ,广播电视技术正面临着一个重大变革时期 ,即广播电视已进入了新的数字电视时代。数字化给广播电视带来了重大的变化 :(1)质量提高 ,透明传送 ,即使远在天边听到的、看到的也如临现场 ;(2 )节目制作运用多种手段 ,使节目丰富多彩 ;(3)节目套数大量增加 ,可实现按需点播节目 ;(4 )实现数据广播等多媒体广播 ;(5 )新一代的广播方式出现 ,如高清晰度电视、数字音频广播等。随着科技推进、电子产业的发展 ,数字电视已进入了实用阶段。进入 2 1世纪 ,模拟向数字的全面过渡正快速进行。我国也正在积极推动这项过渡。整个广播电视系统组成可以…     

数字电视接收机顶盒浅析

目前,数字电视广播是一个从节目采集、制作、传输、到用户端接收机顶盒(STB)都以数字方式处理信号的端到端系统。数字电视接收机顶盒是指以模拟电视机为显示终端的信息接收和处理设备,它能使用户终端模拟电视机从被动接收模拟电视转为交互式接收数字电视和数据广播,并能接入Internet,使用户享受数字电视、数据广播和Internet接入等全方位的信息服务。 1 数字电视接收机顶盒结构 数字电视接收机顶盒包括硬件和软件两部分,它可以分为4层,从底向上分别为:硬件、底层软件、中间件(Middleware)和应用软件。硬件提供数字电视接收机顶盒的硬件平台。底层软件提供实时操作系统     

直放站的原理与应用

直放站是随着移动通信的发展而出现的一种无线通信设备。直放站的应用在第一代模拟移动通信网建立时就已经开始，当时的设备体积大、价格高、指标较差，使用中经常对网络造成干扰。目前使用的直放站设备外观和指标已经大大改善，但调试不好也会影响系统的性能。直放站的大量应用是近两年的事情，尤其随着CDMA网开通和GSM网的深度覆盖，制造厂家明显增多。     

5G演进：网络控制直放站

射频直放站在 2G、3G 和 4G 的部署均用于增强蜂窝网络的覆盖。虽然传统射频直放站提供了一种经济高效的方法用于扩展网络覆盖范围,但其仅能依照固定配置对信号执行放大和转发操作,无法依照网络调度和控制对该行为进行灵活调整。介绍了 5G 演进中的网络控制直放站,作为对传统射频直放站的增强,网络控制直放站具有从网络侧接收针对直放站控制信息的能力,并依据此信息以更有效的方式执行其放大和转发操作,包括实现信号在空间域的定向增强、直放站的动态使能和简化的网络集成。     

The development of a high definition television (HDTV) terrestrialbroadcasting emission mask

This paper analyzes the case of HDTV channels, upper and lower, first adjacent to an existing NTSC station assignment and considers the interference from an HDTV adjacent channel, spillover spectra as undesirable co-channel interference into the NTSC channel. A subjective weighting function is developed for random noise interference to NTSC images at the video baseband level. A filter function representing the human visual system at specified viewing distances as a function of image height is developed, first for monochrome, and then extended to color images. The baseband subjective weighting function is modified to include the process of television carrier modulation and demodulation. This carrier modified weighting function is then used to evaluate typical spillover spectra created by high power amplifiers when driven by a modulated digital HDTV signal. BTSC stereo audio (with SAP) is also included in the interference evaluation. Spectral out-of-band spillover limits are established based on the threshold of visibility of the interference as a function of the mileage separation between adjacent channel NTSC and HDTV stations. A high power bandpass filter and band elimination notches are included in the analysis. The results are then applied to two methods of determining spectral emission compliance: measurement of the out-of-band interference spectra with a weighting function, or alternatively, the use of an emission mask     

SDH在数字电视建设中的应用

由于技术和经济上的优越性，数字化的广播电视是公认的发展方向，已经被列入国家计委、科委等机构的重点发展项目目录。