International Standards for Vertical Interval Test Signals

In the interests of facilitating the international exchange of television programs, the International Radio Consultative Committee (CCIR) at its XII Plenary Assembly in New Delhi in January-February of 1970 approved a new recommendation unendation for international vertical interval test signals. The recommendation covers both major television systems, the 625-line/50-field and 525-line/60-field systems, and specifies the lines in the vertical blanking interval that are to be reserved for this purpose. Additionally the recommendation details the specific waveforms, or test signal elements, for the 625-line/50-field systems. These waveforms represent the results of years of technical discussions among transmission experts of the countries involved. They are described in some detail for the information of U.S. broadcasters as well as broadcasters in other countries using the 52-line/ 60-field systems, since many of these same deliberations have also taken place and will continue to take place in the development of the international vertical interval test signal for 525-line/60-field transmissions.     

Simplified 6.3 Mbit/s Codec for Video Conferencing

A color TV codec with a 6.3 Mbit/s transmission bit-rate has been simplified by a newly developed coding method. This method is the combination of a 4-to-1 dot interlace system and 4 bit/pel DPCM. A digital filtering technique for reducing coding distortion is also employed. In comparison with an interframe codec having the same transmission bit-rate, the amount of codec circuitry is halved. Subjective tests were performed to investigate the coded picture quality. It was found that this codec can present acceptable pictures for video conferencing, and that the picture quality for rapidly moving subjects is the same as that of the interframe codec operating at the same bit-rate. A video conferencing system via a digital satellite link has been constructed for experiments by employing this codec. The experiments showed that the satellite link has a sufficiently low transmission error rate for the coded pieture transmission. Moreover, it has been proved that transmission delay does not pose any problems for normal conferences.     

15/30 Mbit/s Universal Digital TV Codec Using a Median Adaptive Predictive Coding Method

This paper describes a 15/30 Mbit/s TV codec with a new approach to high-efficiency coding for TV signals, i.e., median adaptive prediction. The 15/30 Mbit/s codec, commonly applicable to NTSC, PAL, and SECAM (525/60 and 625/50) systems, uses adaptive prediction incorporating a motion-compensated interframe, an interfield, and an intrafield predictor. Its performance for digital transmission is presented. This universal codec is designed, based on CCIR recommendations concerning digital TV coding parameters for studios (Rec. 601) and general principles on long-distance digital TV transmission (Rec. 604). A field trial of 15 Mbit/s digital TV transmission using this codec between earth stations with a 30 m diameter antenna and a 5 m diameter antenna is reported.     

An error-correcting code for data broadcasting and its error-correction capability

By using the vertical blanking period of television signals, it is possible to transmit coded data such as teletext, newspaper, telesoftware, music score, etc. However, the quality of ordinary TV channels is very poor for digital communications and a powerful error-correcting code is required to reliably transmit coded data. From the results of simulations using error pattern data collected in field tests and the comparison of various error-correcting codes under many conditions, it has been determined that the shortened (272, 190) majority-logic decodable difference-set cyclic code is a suitable code for NTSC TV signals. Moreover, the decoding algorithm for this code has been improved in order to increase the error-correction capability and a new LSI with this function has been developed. By using error-correcting codes proposed to date for teletext, it has been difficult to obtain a page error rate (PER) of 10⁻¹in many measurement points. However, PERs of less than 10⁻² can be obtained in this system, even when random noise, ghost interference, or waveform distortion are present and bit error rates (BERs) are 10⁻². This paper also gives PERs according to the error-data collected in field tests and shows that the error-correction capability increased equivalently up to 11 error-bits in a 272-bit by improving the decoding algorithm and the results of indoor and outdoor tests.     

Orthogonal Transform Coding System for NTSC Color Television Signals

A two-dimensional, 32nd-order orthogonal transform coding system which performs three types of transformations in realtime for NTSC color television signals has been developed. This paper reports on a hardware realization of this system, the optimum bitassignments for 32 and 22 Mbit/s transmission rates and the effects of bit errors during transmission. Through the evaluation of picture quality, the system gave a fine quality of pictures after compressing an 8-bit digitized television signal into 3 bits/pel corresponding to 32 Mbit/s transmission, and a passable quality of pictures by 2.25 bits/ pel corresponding to 22 Mbit/s transmission.     

8Mbit／s数字电视系统的设计与实现

介绍了８Ｍｂｉｔ／ｓ数字电视系统的系统构成，给出了图象压缩编解码，声音压缩编解码和数据通信接口的实现方案，对系统中所采用的新缓存控制策略也作了分析。     

Development of an Error-Correction Method for Data Packet Multiplexed with TV Signals

By using the vertical blanking period of television signals, it is possible to transmit coded data such as teletext, telesoftware, music, etc. However, the quality of data transmission on television transmission channels is very poor and a powerful error-correction code is required to reliably transmit coded data. From the results of simulations using error pattern data collected in field tests and the comparison of various error-correction codes under many conditions, it has been determined that the shortened (272, 190) majority-logic decodable difference-set cyclic code is a suitable code for NTSC TV signals. By using error-correction codes proposed to date for teletext, it has been difficult to obtain a page error rate (PER) of 10^-1in many measurement points. However, PER's of less than 10^-2can be obtained in this system, even when random noise, ghost interference, or waveform distortion are present and bit error rates (BER's) are 10^-2. This paper also gives an empirical equation according to the error data and shows that the error-correction capability increased equivalently up to 11 error-bits in a packet by modifying the decoding algorithm.     

Component codec standards for high-quality digital television

Work towards defining standards for digital television transmission codecs has been proceeding for many years. A draft specification for 140 Mbit/s coding using blanking removal and differential pulse code modulation is given in CCIR Recommendation 721. A draft specification for a codec operating at 30-45 Mbit/s and using the discrete cosine transform has been defined by the European Telecommunications Standards Institute. The author briefly reviews bit-rate-reduction techniques and describes the 140 and 34 Mbit/s codecs     

数字电视数据下载器的设计应用

利用数字电视广播信道可以实现大容量的数据传送,与互联网相比具有占用资源少、服务质量(QoS)有保证等特点,在深圳清华大学研究院数字电视前端系统紫荆神网的基础上,设计实现了比现有数据广播协议更简便的低成本数据下载终端.测试结果表明,其可以实现5 Mbit/s以上的数据下载速率.实现了可移动、定时自动下载的功能.     

Multimedia services and data broadcasting via satellite

Since 1995 EUTELSAT, as well as other service providers (in Europe and worldwide), in collaboration with industrial partners and research institutions have been developing digital platforms for providing multimedia services as well as data broadcasting via satellite services. These digital platforms are based on the same technologies as those used for the emerging digital television and radio services, namely Digital Video Broadcasting (DVB) and MPEG-2. These platforms will greatly improve the speed of multimedia services to the end user (e.g. up to 2 Mbit/s per session on an Internet connection) and will provide the possibility of downloading very large files in a very short time (e.g. downloading speeds of up to 40 Mbit/s per transponder) to a very large number of customers. By using the same technology as for digital television and radio, large economies of scale are foreseen, thus making these digital platforms very affordable on both the unlink side and the receiver side (e.g. less than $300 for the DVB-PC card kit)     

1.544 Mbit/s Data Above FDM Voice and Data Under FDM Voice Microwave Transmission

Methods are presented for the transmission of wideband digital signals above and below the frequency division multiplexing (FDM) baseband spectrum of analog microwave systems. In particular, it is shown that a Data Above Voice (DAV) system employing a 1.544 Mbit/s data channel above FDM channels and a Data Under Voice (DUV) system employing 1.544 Mbit/s channel below 720 FDM channels, are practical hybrid systems. Theoretical models of hybrid transmission are disucssed and the DAV/DUV methods are compared. A conceptual hybrid system design procedure is introduced and field measurement results on an 8 hop 6 GHz system are presented, comparing favorably with theoretical predictions.     

A 1/2-in 1.3 M-pixel progressive-scan IT-CCD for digital stillcamera applications

A 1/2-in 1.3 M-pixel progressive-scan interline-transfer charge-coupled-device (IT-CCD) image sensor has been developed for small, low-power mega-pixel digital still cameras (DSCs). The pixel size as small as 5 μm square makes small-size progressive-scan IT-CCD (8.3×7.1 mm²) for the SXGA format. A two-phase-drive horizontal-CCD with phosphorus-implanted storage regions helps reduce the driving voltage to 2.5 V, resulting in the power consumption of the device being as low as 146 mW. A new source-follower amplifier with separate p-well driver transistors achieves 12% higher gain than that obtained using a conventional amplifier. An overflow drain with a self-adjusting potential barrier can instantly remove superfluous charges in vertical-CCDs just before an exposure period, which enables DSCs to perform such functions as quick auto-focusing and dark-current removal. New dual operation modes for still and motion pictures can provide not only high-resolution color signals in a 15-frame/s 1050-line progressive mode but also wide-dynamic-range color signals in a 30-frame/s 525-line progressive mode. The latter mode employs a pixel-exchange-and-mix readout operation that helps halve the number of scanning lines with no loss in sensitivity and color information     

全数字化HDTV传输系统图像信源编码的研究

本文研究了一种全数字化HDTV传输系统图像信源编码方案。将运动补偿帧间预测,离散余弦变换编码和二维熵编码技术结合起来,通过对码率的自适应调节,实现HDTV图像信号的压缩编玛。在14.38Mb/s和20Mb/s码率,取得了良好的图像质量。应用数字调制技术,如16-QAM,能够实现在一个基带8MHz射频信道中传输全数字化HDTV。     

Mobile teletext reception using signal processing in frequencydomain

An experimental study of mobile teletext reception is described. Teletext in Japan is a broadband signal with 5.73 Mb/s; therefore, multipath interference is a serious problem in mobile reception, and it is impossible to obtain the teletext correctly by conventional methods. A multipath reduction technique using signal processing in the frequency domain is developed. In this technique, an original chirp signal is used for reference to identify the radio propagation path. In field trials, the delay profile was precisely obtained, and the bit error rate was reduced. The error correction capability was tested in a computer simulation     

32 Mbit/s Transmission of NTSC Color TV Signals by Composite DPCM Coding

A composite DPCM coding System was developed, which is capable of coding and transmitting an NTSC color TV signal without component separation at a 32.064 Mbit/s rate. The DPCM prediction method used is based on the algorithm that a luminance component prediction valuehat{y}and a carrier chrominance component prediction valuehat{c}are calculated individually, and then the composite signal prediction valuehat{x}is determined byhat{x} = hat{y} + hat{c}. In order to utilize horizontal blanking (HBL) intervals for transmitting active video signals,HBL signals are not transmitted in each line but their representative signals are transmitted once a frame during a vertical blanking interval. A dual word-length coding and quantizing method is adopted, which uses 4 bit and 8 bit words with average word-lengths of 4.4 bits/sample. Codec equipment was fabricated, and coding and transmitting experiments were conducted, using NTT's PCM-100 M digital repeatered line. Experimental results show that this composite DPCM coding system can be employed for digital transmission of NTSC color TV signals, such as color ITV signals, at a 32.064 Mbit/s rate.     

Design of integrated services digital broadcasting systems usingmultirate optical fiber code-division multiplexing

This paper presents the design of a new type of integrated services digital broadcasting (ISDB) systems which use a multirate optical fiber code-division multiplexing (OF-CDM) technique. The proposed system can efficiently multiplex various kinds of digital signals with multiple bit rates. This is feasibly achieved by using strict optical orthogonal codes of both auto- and cross-correlation constraints being “1” in multirate OF-CDM systems. Moreover, the low-cost design of OF-CDM transmitters is presented, and experimental demonstrations are also carried out. The measured results show that a transmission distance up to 13 km can be feasibly accomplished by using the proposed transmitter design and the external optical injection-locking scheme. It is expected that the proposed ISDB systems can be employed to cost-effectively transmit fast ethernet (125 Mbit/s), FDDI (125 Mbit/s), ATM (155 Mbit/s), and ESCON (200 Mbit/s) protocol data. Their potential applications include Internet services and multimedia broadcasting, such as videoconferencing, video on demand, HDTV, distance learning, and World Wide Web     

A coherent multichannel demonstrator

The authors describe an advanced coherent multichannel (CMC) communications demonstrator that has been designed by the RACE 1010 consortium. This fully engineered demonstrator examines the application of CMC techniques to broadband signal distribution (e.g. television and high-definition television) in the local loop. Ten 140 Mbit/s digitised video signals are transmitted on ten optical carriers 10 GHz apart. Up to 1000 receiver terminals can be served from a single central transmitter assembly. The authors explore the system operation, system specifications, and subsystem results that have been achieved     

Performance of interframe predictive coders for television signals under various conditions of motion

Subjective tests are reported, at 3 bits/pel, of the performance of several predictive coders for monochrome 625-line television signals under five different conditions of motion, including panning and scene changes. The results indicate that interframe prediction, used on a selective basis, can produce a worthwhile improvement in picture quality over that possible by intraframe prediction alone.     

Performance of an error correction scheme for PAL-TV teletext

The shortened (272, 190) difference set cyclic code has been adopted for the Japanese teletext system using NTSC vertical blanking periods. This system is known as BEST (burst and random error correction system for teletext) for NTSC-TV systems. A powerful error correction system adopting the (272, 190) code for PAL-TV teletext signals is described. To compare the error correction characteristics of this system to those of WST (World System Teletext), transmission experiments were carried out multiplexing both data packets with different lines during the vertical blanking period of the same TV signals. The validity of applying BEST to the PAL-TV signals was confirmed, particularly when there is ghost interference