美国“大联盟”HDTV系统方案

美国“大联盟”ＨＤＴＶ系统是为满足北美需求而设计的，它完全基于国际标准，具有很强的灵活性和互操作性。“大联盟”和美国联邦通信委员会的先进电视顾问委员会共同完成了“大联盟”ＨＤＴＶ系统的设计。系统样机正在研制，测试工作从１９９４年底开始。本文描述了“大联盟”ＨＤＴＶ系统的技术特性。     

’96中国VXI应用技术大会成功举行专家云集探讨VXI总线技术

’９６中国ＶＸＩ应用技术大会成功举行专家云集探讨ＶＸＩ总线技术刘洪由中国计量测试学会ＶＸＩ技术委员会等单位发起组织的’９６中国ＶＸＩ应用技术大会，于５月１３日至１５日在北京举行。此前还举行了ＶＸＩ应用决策高级研讨会。这次大会开得非常成功，堪称我国仪器...     

消费类电子产品数字化时代正向我们走来

数字技术正在迅速进入消费类电子领域。在今后几年里，数字化消费产品与服务将火箭般直冲云霄，家用电器最终将发生天翻地覆的变革。ＨＤＴＶ与ＤＢＳ先进电视（ＡＴＶ）标准的制定是防止家用电子行业混战的最成功因素。高清晰电视（ＨＤＴＶ）就是ＡＴＶ的一个具体实施方案。１９９５年底，美国电子行业商定了ＨＤＴＶ标准（每秒６０帧，每帧１２８０行Ｘ７６８个像素）。有关文件已呈送美国联邦通信委员会，该委员会今年将给予审批。这个ＨＤＴＶ标准能容纳一般清晰度电视（图像清晰度较低），而且可以容纳非视像服务和辅助服务用的数据流…     

FCC开始实行两年一次的DTV考察

美国联邦通信委员会 (ＦＣＣ)开始了对数字电视播出的首届两年一次的考察 ,邀请公众对关于美国数字电视状况的一系列问题提出意见。该委员会特别需要对下列问题的意见 :是否采纳ＤＴＶ业务反复实验要求以及是否需要增强型业务 ;是否委员会应给广播机构一个选择其后过渡频道的期限以及如何解决互斥的ＤＴＶ和ＮＴＳＣ应用。这届两年一次的考察被授权作为ＦＣＣ第五次报告和命令的一部分 ,但它只是由于驳回辛克莱 (Ｓｉｎｃｌａｉｒ)广播集团改变ＤＴＶ标准的请求而成熟了。由于驳回了该请求 ,委员会答应在这次考察过程中检查这个问题。在调制…     

美国FCC关于高级电视（ATV）的举措

美国ＦＣＣ关于高级电视（ＡＴＶ）的举措１９９５年１１月美国联邦通信委员会（ＦＣＣ）的高级电视顾问委员会（ＡＣＡＴＳ）开会并通过了有关高清晰度电视（ＨＤＴＶ）的最后报告和建议。下一步将是正式的政府行动，即发布规则制定通告（ＮｏｔｉｃｅｏｆＰｒｏｐｏｓｅ...     

交流稳压电源分类及其特点

交流稳压电源分类及其特点中国电源学会交流稳定电源专业委员会主任张广明这里提及的仅是指对交流电网电压起稳定作用的设备（ＡＶＲ），至于不间断电源（ＵＰＳ）、稳压稳频电源（ＣＶＣＦ）、变频调速电源（ＶＶＶＦ）等，虽也属于交流稳压电源范畴，但因其性能、用途和...     

GA HDTV系统介绍

ＧＡＨＤＴＶ系统是由美国大联盟和ＦＣＣ先进电视业务咨询委员会共同研究设计的。它的设计是依据国际标准，具有极大的灵活性和广泛适用性，对我国的ＨＤＴＶ研究工作具有重要的参考价值。     

数字电视

在数字技术高速发展的今天,对我们来说,数字电视（ＤＴＶ）不再是个陌生的词。但呼之欲出的数字电视到底是个什么东西,它有什么特点,它与ＨＤＴＶ、ＳＤＴＶ有什么区别？它的发展到底怎样？１　数字电视和ＨＤＴＶ、ＳＤＴＶ数字电视（ＤＴＶ）、ＳＤＴＶ、ＨＤＴＶ是广播电视界时常提及的三个名词,它们之间既有联系,也有区别。ＨＤＴＶ（ＨｉｇｈＤｅｆｉｎｉｔｉｏｎＴＶ）起源于日本,是高清晰度电视的缩写,代表高质量图像和杜比数字环绕立体声。ＣＣＩＲ（国际无线电咨询委员会,现改名为ＩＴＵ）的８０１报告中为ＨＤＴＶ规定…     

宽带数据网基础知识讲座(1)数据技术的基础知识

1　引言Ｉｎｔｅｒｎｅｔ借助全球的ＰＣ(计算机 )Ｗｅｂ(网络 ) ,以多媒体技术为传播手段 ,被联合国新闻委员会确定为继报刊、ＢＣ(广播 )、ＴＶ(电视 )之后的第 4媒体。在赋予传统ＢＣＴＶ崭新内容和形式的同时 ,又对之构成了威胁和挑战。为适应全球信息化、Ｗｅｂ化的需求 ,ＢＣＴＶ亟待掌握数字技术 ,进入宽带数据Ｗｅｂ的服务时代。(1)数据Ｗｅｂ技术的迅猛发展给ＢＣＴＶ带来了一场意义深远的革命 ,与传统模拟时代的ＢＣＴＶ技术体系相比 ,数字信息时代的ＢＣＴＶ技术体系有其崭新的特征。①传播方式从单向、固定转变为交互、移动 ;②…     

蚕豆萎焉病毒2号侵染豌豆的细胞病理变化

蚕豆萎蔫病毒 (Ｂｒｏａｄｂｅａｎｗｉｌｔｖｉｒｕｓ ,ＢＢＷＶ)是豇豆花叶病毒科 (Ｃｏｍｏｖｉｒｉａｄａｅ)蚕豆病毒属(Ｆａｂａｖｉｒｕｓ)的代表种 ,其寄主范围很广 ,可侵染 4 4个科 186属中的 32 8种植物[1] ,是我国豆科作物、蔬菜作物、中草药、花卉、烟草及一些木本植物上的重要病毒病原。国际病毒分类委员会 (ＩＣＴＶ)第六次报告中已将原先的两个血清型划定为两个种 ,即蚕豆萎蔫病毒 1号 (ＢＢＷＶ1)和蚕豆萎蔫病毒 2号(ＢＢＷＶ2 ) ,在我国广泛发生的都是ＢＢＷＶ2 ,尚未分离到ＢＢＷＶ1。自 1994年起 ,周雪平等系统研究了ＢＢ…     

Analysis of ATV transmission subsystem field test data

This paper examines the data from the field test of the Grand Alliance HDTV transmission subsystem conducted in Charlotte, NC in 1994. The field test data provides HDTV system designers and researchers with first-hand information on the performance of digital HDTV terrestrial broadcasting as well as on NTSC performance in the real-world environment. Analyses of the field test data are performed with respect to the system performance of an 8-VSB digital transmission subsystem, the performance of NTSC as reference and the television channel characteristics. Observations and conclusions derived from the analyses are provided     

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     

High Definition Television (HDTV)--Compatibility and Distribution

High definition television (HDTV) pictures are, by all accounts, dramatically superior to today's NTSC color television, both in resolution and in realism. Picture quality approaching that of 35 mm color film is obtainable by most systems under investigation in recent years. One of the basic premises of a recent SMPTE study was that "the HDTV signal should be capable of a standards conversion ... to the NTSC ... domestic service." Otherwise, there would be "so many political, social, and economic Impediments that [HDTV] might never succeed ...." However, the same study wound up by concluding that such compatibility was "not feasible by any means known ... or envisaged." Here we suggest a possible solution to the compatibility dilemma. We propose an HDTV signal with a camera line-scan rate exactly twice that of NTSC. From this we construct an intermediate waveform called the semicompatible-high-definition television signal (SCHDTV), which has the virtue of being easily convertible to an NTSC picture. The SC-HDTV signal requires three present-day CATV channels for local distribution and is suitable for transmission via direct broadcast satellite (DBS). Moreover, HDTV could also be sent on most present-day satellite facilities if the SC-HDTV signal were split into two parts and two transponders were used.     

Hierarchical NTSC compatible HDTV system architecture — A North American perspective

High definition television (HDTV) has become a major world-wide event in the television arena. Since the early 1980s, when HDTV was first demonstrated by Japan, a number of alternative systems have emerged. These systems clearly reflect the business and political objectives of the particular countries or organizations. In North America, which is the largest single consumer market in the world, technical, business and political considerations are shaping the evolution of HDTV. This paper describes a possible advanced television (ATV) architecture for North America and defines its functional modules and corresponding interfaces. The developed model is recommended as a design tool for standardizing ATV in North America and analysing interrelationships of the functional modules on the economic basis. The paper proposes an ‘hierarchical’ ATV emission system with full NTSC compatibility and HDTV quality. Solutions are recommended for terrestrial broadcast, CATV and satellite. This work describes a total systems approach to HDTV called HDS-NA (high definition system for North America). The two emission signals of HDS-NA: HDMAC-60 and HDNTSC are characterized. RF alternatives for the terrestrial broadcast of HDTV are also discussed.     

Advanced digital HDTV transmission system for terrestrial videosimulcasting

Transmission aspects of the advanced digital high definition television (AD-HDTV) system, for terrestrial simulcast delivery of HDTV are described. In AD-HDTV, two quadrature-amplitude-modulated (QAM) carriers, with different power spectral densities, are employed in a frequency division multiplex (FDM) mode within the standard 6-MHz channel. The resulting spectral shaping allows a larger power to be transmitted, compared to that for a single QAM carrier, for the same level of perceptual interference into cochannel NTSC. The coded video data are split into high-priority (HP) data and standard-priority (SP) data, and the vital information is sent on the appropriate QAM carrier, resulting in a robust audio and video transmission system. The availability is higher in scenarios where the carrier-to-noise ratio (CNR) is above the threshold for HP reception but below the threshold for SP reception; this is important in fringe areas. The NTSC planning factors, suitably modified for HDTV delivery, are used to estimate the coverage area for AD-HDTV. The calculated AD-HDTV coverage area of 54.5 miles is comparable to that for NTSC transmission     

Testing HDTV terrestrial broadcasting systems

The Advanced Television Test Center (ATTC) is a private sector, nonprofit organization created to undertake full, fair, and impartial testing of the various advanced television (ATV) systems that have been proposed as the United States terrestrial broadcast standard. Cable Television Laboratories (CableLabs) organized by the cable television industry operates, in cooperation with ATTC, a state-of-the-art laboratory testing facility capable of thoroughly evaluating the proposed ATV systems when transmitted by cable TV, including both coaxial cable and fiber-optic transmission. Presently there are six systems scheduled for test by the ATTC and CableLabs. The systems and their scheduled test dates are shown. One of the systems is an enhanced NTSC compatible system and the other five are high-definition television (HDTV) simulcast systems. Four of the simulcast systems are digital. Both objective and subjective tests of all six systems are discussed     

Hierarchical Evolution of High Definition Television

This paper presents an economically attractive system for the hierarchical evolution of High Definition Television (HDTV) compatible with the NTSC installed base. It describes the two main signals of this system: HDMAC-60 and HDNTSC. The first, HDMAC-60, is a feeder signal for use between the program origination and program redistribution points, and used also as a DBS emission format. The second, HDNTSC, is a delivery signal for high definition terrestrial broadcast, CATV distribution and VCR plus laser video disc applications. We propose this emission system as a means for transmitting HDTV pictures to consumers on the North American continent.     

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     

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.