Modeling Broadcast Teletext Systems for Analysis and Computer Simulation Studies

An isomorphism is derived between a typical bandpass broadcast television system to be used in transmitting teletext data and its complex baseband equivalent representation for use in analysis and computer simulations. The distortions introduced by a multipath channel are discussed. The complex noise process is modeled by a mixture of Gaussian and impulsive noise, and the parameters of the noise model are derived. The video signal-to-noise ratio SNRTVis related to other parameters such as the input noise variance, output noise power, and the carrier-to-noise density ratio. A complete simulation model for broadcast television transmission and reception is shown in block diagram form. The remaining components of the computer simulation model are briefly discussed and references given. These include topics such as amplitude control, computer generation of ensembles of complex impulse responses, simulation of synchronous, quasi-synchronous and envelope detectors, bit slicers, bit synchronizers, error-correcting codes, estimation of error statistics and bit error rates, and adaptive equalization. Validation is also briefly noted with references. Several examples of simulation results are given. Some of the implementation details, simulation results, and a flow diagram of the simulation program are provided. This teletext computer simulation model appears to be the most complete one created to this time and has been used extensively in performance analyses to evaluate new designs and gain insights into design improvements.     

广播电视网中的图文电视

在广播电视技术发展异常迅速的今天,人们不仅仅局限于通过广播电视收看自己喜欢的丰富节目,更重要的是通过它进行多项综合业务的开展和应用。信息传播媒体的发展引起了广播电视、通讯、计算机三大网络的新的竞相挑战,然而,图文信息的产生又为广播电视提供了新的课题,图文信息正以不同于报刊、杂志之类的单板式宣传方式进行传播经济、生活、影视、文体、综艺及法制等信息外,还具有其自身的新奇独特的优点广泛地被大家所接受,随着广播电视网络的高速发展,深信图文电视信息的作用越来越重要。下面立足现实,谈一谈有关图文电视方面的问题。     

南昌有线电视台图文数据播出系统

１９９６年底 ,我台与证券公司合作开办了正程股票即时行情播出频道 ,试播效果良好。此后 ,我们又对开办逆程股票即时行情播出业务进行了可行性论证 ,得出以下几点结论 :(１)能方便快捷地获得深沪股市即时行情信息是股民们的迫切需求。(２)开展该业务前端只需增设几台信息处理播出计算机 ,现有网络无需改造 ,即可正常运作 ,投入少 ,见效快。(３)接收机的成本由于其内部芯片可大批量生产 ,成本不断降低 ,适于进入家庭。因此 ,我台于１９９７年初试播图文数据广播 ,经不断增添设备建成了含３套逆程图文及两套正程图文播出的计算机网络系统。１…     

全自动中文新闻字幕生成系统的设计与实现

本文设计与实现了一个全自动中文新闻字幕生成系统,输入为新闻视频,输出为视频对应的字幕文本.以<新闻联播>为语料,实现了音频提取、音频分类与切分、说话人识别、大词汇量连续语音识别、视频文件的播放和文本字幕的自动生成等多项功能.新闻字幕的自动生成,避免了繁重费时的人工字幕添加过程.实验表明,该系统识别率高,能够满足听障等特...     

Design and Installation of Limited-Area AM Broadcast Systems

This paper discusses the design and installation of low-power AM broadcast systems using power-line-carrier techniques. Such systems permit coverage of listeners in dormitories and similar structures. This discussion covers technical aspects of the propagation medium, typical design objectives, and related economic considerations. Spectrum-regulation issues pertaining to North America are covered, with related matters like selection of operating frequency and control of undesired radiation. By supplementing the rather meager technical literature on this topic, this discussion may prove useful to the broadcast engineer who is called upon to design or expand one of these systems.     

珠海电视台高清频道播出系统设计与应用

在全球高清大背景下,珠海电视台前瞻性规划,新建两套高清播出系统,主要介绍新改造的珠海电视台高清频道和标清频道的现状,一些重要硬件设备的选型和主要技术指标、型号、规格和参数,以及一些软硬件需要注意的问题。     

On the Optimality of Cyclic Transmission in Teletext Systems

Teletext is a one-way information delivery system where pages of information are broadcast to all users in a continuous manner. System response time is an important consideration in the design of teletext systems. One factor contributing to response time is the order in which pages are transmitted. In this paper, we formulate the problem of determining the sequence of page transmissions as a Markovian decision process. Using this formulation we show that, from a response time point of view, a cyclic order of page transmissions is optimal. We also describe two algorithms for designing a teletext broadcast cycle.     

Optimal Reliability Design of Process Systems

The optimal design of system reliability which takes into account the quantitative aspect of systems throughput or capacity is proposed. It is based on the concept of an r-out-of-n configuration instead of the conventional parallel 1-out-of-n configuration and is especially suitable for treating problems which arise in process systems. The problem is solved by the pseudo-Boolean programming method of Lawler and Bell.     

Pulse Shape Design for Teletext Data Transmission

This paper studies the problem of designing a suitable pulse shape for teletext data transmission. The following four criteria are used: 1) Nyquist I criterion, 2) Nyquist II criterion, 3) degree of overshoots in the channel signal, and 4) robustness to sampling phase jitter. For system bandwidths less than the inverse-baud rate, it is not possible to satisfy all these criteria simultaneously; tradeoffs that have to be made are illustrated. Several candidate pulse shapes are given and a composite criterion developed. A pulse shape, which satisfies the Nyquist I criterion and is closest to satisfying the Nyquist II criterion, in a sum-of-squares-of-deviations sense, is recommended.     

图文电视中大容量数字存储器的设计

提出了图文电视中的大容量数字存储器电路设计方案，详细描述了设计的基本思想和两个ＦＰＧＡ功能模块的具体实现，简要介绍了图文电视的基本概念。     

电视片字幕的设计与制作

字幕是电视片的重要组成部分,是电视片信息传播的重要补充.为有效发挥字幕的功效,本文重新认识字幕的意义与作用,分析电视荧屏的特性与字幕设计的相互关系,阐述字幕作为电视画面的有机构成要素的设计和制作方法.     

下一代广播电视网无线系统

基于下一代广播电视无线网（NGB-W）技术需求分析,文章给出了两种广播与双向通信融合的网络架构,讨论了下行广播传输、广播与通信融合数据推送、双向无线接入、频谱感知等方面涉及的关键技术,并探讨了NGB-W的应用前景。文章认为采用广播与双向通信融合网络,NGB-W系统可以充分利用超高频（UHF）频谱资源,根据各种信息业务的不同特点,有针对性地分配网络资源和频谱资源,选择最优传输方式,从而提高系统整体无线频谱利用率。     

流媒体广播及点播系统的设计与应用

分析视频课件制作和视频流传送的基本过程，提出基于MPEG-4的流媒体视频课件广播／点播系统的设计和实现方法，为当前开展远程网络实时教学和视频点播提供新的思路。     

Compatible High Definition Television Broadcast Systems

This paper describes NTSC compatible HIDTV systems with incremental improvement potential. The systems are capable of increased horizontal and vertical resolution, reduced crosstalk between the components, and a wide aspect ratio. Experimental results on a split-luminance system show that 600 lines of horizontal resolution are achieved after the luminance signal band has been divided at the encoder and recombined at the decoder. Spatial splitting of the picture is employed to increase the aspect ratio. A low cost HDTV system is also presented that uses a modulated-signal combination. With this system, considerable simplification is possible with a slight reduction in resolution. All proposed systems are fully NTSC compatible and utilize two standard 6 MHz channels for transmission. The improvements can be realized incrementally because of their downward compatibility at the receiver.     

Spatial Queries in Wireless Broadcast Systems

Owing to the advent of wireless networking and personal digital devices, information systems in the era of mobile computing are expected to be able to handle a tremendous amount of traffic and service requests from the users. Wireless data broadcast, thanks to its high scalability, is particularly suitable for meeting such a challenge. Indexing techniques have been developed for wireless data broadcast systems in order to conserve the scarce power resources in mobile clients. However, most of the previous studies do not take into account the impact of location information of users. In this paper, we address the issues of supporting spatial queries (including window queries and kNN queries) of location-dependent information via wireless data broadcast. A linear index structure based on the Hilbert curve and corresponding search algorithms are proposed to answer spatial queries on air. Experiments are conducted to evaluate the performance of the proposed indexing technique. Results show that the proposed index and its enhancement outperform existing algorithms significantly.     

用UML设计通用DVB图文电视处理组件

提出了一种针对DVB图文的终端软件解决方案,介绍了该方案基于UML技术的建模设计过程,分析了解码,存储,导航等关键功能,提出了操作系统抽象和回调处理页面显示的思想,解决了组件的兼容性和可移植性问题,最终完成了一个可被广泛集成的通用图文处理组件.     

用FPGA实现图文电视中汉字显示系统

近年来图文电视得到了迅速发展。本设计是“图文电视”项目中的一个子项目,即设计图文电视中的汉字显示系统。本文简要介绍了图文电视的基本概念,详细描述了设计的基本思想和两个FPGA功能模块的具体实现。     

广播电视系统及设备可靠性与环境测试

本文介绍了广播电视系统及设备进行可靠性与环境测试的原则和方法,重点介绍了一些主要在室外使用的设备在测试时所参照的标准和测试方法。此外,介绍了应用于广播电视系统及设备的可靠性与环境测试中所使用的主要设备仪器。以上测试的开展,为广播电视系统和设备的稳定性、可靠性测试提供了实践基础,保证了整个广播电视设备制造行业的良性的、可持续发展。     

MB-OFDMUWB系统中导频图样的最优化设计

在MB—OFDMUWB系统中,导频图样对信道估计的影响较大,为了甄别这些影响,并寻找到较优的导频图样,根据信道的最大多径时延和最大多普勒频移以及取样率平衡原理来确定导频的时域和频域间隔,并通过性能仿真对比,得到不同的导频图样对信道估计算法和信道插值算法的影响。通过Matlab仿真实验表明,该方法较传统的导频图样设计方法更快速,具有更好的性能,可为不同信道估计方法中导频图样的选择提供依据。     

DMT系统中信号削波率的最优设计

文章对于离散多音DMT(Discrete Multitone)系统中量化噪声和削波噪声进行了详细的分析．提出了DMT系统中进行削波率最优设计的原则和方法。仿真结果显示经过不同准则的削波率优化设计后，系统要么提高了性能，要么降低了实现复杂度。