1、_- CCIR RECMN*b50-2 92 = 4855232 0559575 771 Rec. 650-2 1 RECOMMENDATZON 650-2* STANDARDS FOR CONVENTIONAL TELEMSION SYSTEMS FOR SATELLITE BROADCASTING IN THE CHANNELS DEFINED BY APPENDIX 30 OF THE RADIO REGULATIONS (Questions 84/11 and 95/11) (1986-1990-1992) The CCIR, considering a) that the intro
2、duction of the broadcasting-satellite service offers the possibility of reducing the disparity between television standards throughout the world; b) that this introduction also provides an opportunity, through technological developments, for improving the quality and increasing the quantity and dive
3、rsity of the services offered to the public; additionally, it is possible to take advantage of new technology to introduce time-division multiplex systems in which the high degree of commonality can lead to economic multi-standard receivers; C) that it will no doubt be necessary to retain 625-line a
4、nd 525-line television systems; d) that broadcasting-satellite services are being introduced using analogue composite coding according to Annex 1 of Recommendation 470 for the vision signal; e) that it is generally intended that broadcasting-satellite standards should facilitate the maximum utilizat
5、ion of existing terrestrial equipment, especially that which concerns individual and community reception media (receivers, cable, re-broadcasting methods of distribution etc.). For this purpose a unique baseband signal which is common to the satellite-broadcasting system and the terrestrial distribu
6、tion network is desirable; 0 that the requirements as regards sensitivity to interference of the systems that can be used were defined by Appendix 30 of the Radio Regulations (RR); 8) that complete compatibility with existing receivers is in any event not possible for frequency-modulated satellite b
7、roadcasting transmissions; h) that, as far as the video signal is concerned: - the basis for the transmission of separate components has been established as an important principle by the CCIR in Recommendation 601; studios using component vision signals will produce pictures of higher quality than p
8、resent-day studios using composite signals; the picture quality with present composite standards is limited by cross luminance/chrominance effects resulting from the band-sharing of luminance and chrominance signals; new technologies are available for receiver design which permits a new approach usi
9、ng separate colour components that are time-compressed and transmitted in time-division multiplex; a separate component approach allows scope for future enhancements of picture quality; - - - - that as far as the sound channels and the data services accompanying the television picture are concerned:
10、 - j) according to $ m) of Decision 51-2, technical developments permit the use of digital techniques to be envisaged; the use of digital coding permits a large improvement in sound quality to be obtained; - * Note from the Director, CCIR - The following Reports of the CCIR were considered in relati
11、on with this Recommen- dation: 624-4,632-4,795-3,802-3,953-2,954-2, 1073-1, 1074-1 and 1228. CCIR RECMN*650-2 92 4855232 0539576 608 2 Ree. 650-2 - it is important to select for adoption, from the systems described in Report 632*, that which offers the greatest possible capacity whilst making the be
12、st possible use of the radio-frequency channels defined by Appendix 30 of the RR, taking into account, if necessary, 0 e) above; the principle of time multiplexing of sound and digital data, on the one hand, and the picture signal, on the other hand, eliminates the problems of intermodulation betwee
13、n the signals; that as far as the multiplexing of the audio signals and the data signals corresponding to the television - it is important to make the best possible use of the capacity offered by the digital modulation system; - it is desirable to use the coding standards for digital audio channels
14、specified in Recommendation 651 and the CCIR special publication “Specifications of Transmission Systems for the Broadcasting- Satellite Service” and to be able to associate with this baseband coding several layers of error protection, in order that it may be adapted to suit the particular requireme
15、nts of the administrations; it is important to ensure maximum flexibility in the multiplexing process, which is to be selected from those whose principles are described in Appendix 2 to Annex 1, in order that the particular requirements of the administrations may be met for the sharing of the availa
16、ble capacity between audio services and data services, to permit this sharing to be modified in time, and to ailow the later introduction of new services that are not yet identified; that the ruggedness of the system should be such as to provide a service down to the lowest possible carrier- - k) au
17、xiliary services defined in Appendix 2 to Annex 1 is concerned: - 1) to-noise ratio, recommends that when a broadcasting-satellite service is introduced in the 12 GHz band channels defined by Appendix 30 - - of the RR, the preferred systems for television services using 625-line and 525-line standar
18、ds (Note i) should be: the systems using multiplex analogue components according to Annex 1 (Note 2); the systems using analogue composite coding for the vision signai as described in Annex 1 or according to Recommendation 470 or for certain administrations in Region 2, variations thereof. Note I -
19、The issue of the transmission signal format for the broadcasting-satellite service is still under consideration in both Canada and the United States of America. Two types, a component television system (B-MAC 525-line as described in Annex 1, 2.2) and several composite television systems based on th
20、e NTSC baseband vision signal format, are included in these considerations. Note 2 - For a number of administrations in Region 1 (those administrations of countries which have active members of the EBU) one member of the MAC/packet family (i.e. C, D, D2) should be used. ANNEX i Television standards
21、for the broadcasting-satellite service 1. Introduction This Annex briefly describes in a comparative manner the basic characteristics of some of the systems which have been developed for television transmission with sound and data services for satellite broadcasting. Recognizing that there are advan
22、tages in reducing the number of modulation methods and the differences in the characteristics of these modulation methods, the basic parameters of each system were used to produce tables which stress the * A Handbook is being prepared that contains descriptions of the essential modulation methods pr
23、esently contained in Report 632-4. - _ CCIR RECMN*b50-2 92 4855212 0519577 544 Rec. 650-2 3 similarities between systems. Only fully specified systems adopted, or being seriously considered for adoption, by at least one administration, were considered in these tables. The detailed specifications of
24、these systems are contained in a separate CCIR publication “Specifications of Transmission Systems for the Broadcasting-Satellite Service”. Special considerations should be given to those systems that have adopted the general principle of time- division multiplexing since it permits an improvement i
25、n the quality of the signais by eliminating, in particular, the problems of intermodulation and cross-colour. A time-division multiplex structure also permits subsequent compatible introduction of further services or further improvements to the quality of the basic services. For example, wide-screen
26、 aspect ratio pictures can be transmitted. Displays of the 4:3 type can present the most interesting portion of the picture, selectable by a digital data signai. Further details are given concerning these improvements to the vision signal in Appendix 1. All systems described in this Annex appiy digi
27、tal techniques for the sound (and for the data) in order to utilize to the greatest possible extent the capacity made available by the channels defined by Appendix 30 of the RR, taking into account if necessary the need for direct translation on distribution networks with narrower bandwidths. The us
28、e of a sound/data multiplex (associated with the service-identification system) making available the capacity required, and at the same time the maximum flexibility, is also a very important asset. Possibilities of scrambling the signal for secure transmission and controlled reception are increasing
29、ly viewed as an important feature of such systems. This Annex presents a short summary of the main features of each of the fully specified systems considered. It is followed by tables listing values for the main characteristics of each system. 2. Summary description of the systems 2.1 MAC/packet fam
30、ily The MAC/packet family of standards has three members all suited to satellite broadcasting: C-MAC/packet, D-MAClpacket and D2-MAClpacket. These systems have been optimized under different constraints and meet the v,uious broadcasting-satellite service requirements in the 12 GHz band when the 625-
31、line standard is used with a mtellite channel of 27 MHz bandwidth. The systems incorporate the following common features: - time division multiplexing; - MAC picture coding, with the capacity for extended aspect ratio; - packet multiplexing for sound and data; - digital high and medium quality sound
32、 coding and error protection method (see Recommendation 651 and the CCIR special publication “Specifications of Transmission Systems for the Broadcasting- Satellite Service”); - service identification and conditional access systems with video and audio scrambling system specifications issued by seve
33、ral organizations; - full channel digital mode, when the area of the television frame normally reserved for the MAC vision signal (and its blanking interval) is replaced by data burst (see Recommendation 712). The clock frequencies used in these three systems have simple relationships with the sampl
34、ing frequencies of the digitai studio standard defined in Recommendation 601. This close relationship between these systems ailows for the development and introduction of receivers capable of functioning with all of the standards. CCIR RECMN*bSO-2 92 = 4855212 0539578 YB0 - I 4 Rec. 650-2 2.1 .I C-M
35、AC/packet The C-MAC/packet system was, in part, developed to provide a high data channel capacity. The particular features of the C-MAC/packet system are: - the use of an RF time division multiplex wherein the carrier is frequency modulated by analogue picture signals during a certain fraction of li
36、ne duration and 2-4-PSK modulated during the remainder of the line duration by a multiplex conveying several sound channels, synchronization and data signals; - the capacity of the sounddata multiplex is about 3 Mbit/s, equivalent to eight high quality sound channels of 15 kT3i bandwidth with near i
37、nstantaneous 14/10 bit companding (protected by one parity bit per sample). The spare data capacity can be used for other services. 2.1.2 D-MAC packet The D-MAC/packet system was, in part, developed to provide both a high data channel capacity and a single baseband interface to other transmission an
38、d distribution media. The particular features of the D-MAC/packet system are: - a baseband time division multiplex in which the analogue picture signals are combined with duobinary encoded digital sound, synchronization and data signals; - the capacity of the sounddata multiplex is about 3 Mbit/ - t
39、he single baseband representation of the time division multiplex signal is frequency modulated for satellite broadcasting. The D-MAC/packet system has been under further investigation by experts of a number of organizations and has also been shown to be suitable for satellite broadcasting. As a resu
40、lt of these developments, the United Kingdom and Norway now use the D-MAC/packet system for their 12 GHz band broadcasting-satelfite services. 2.1.3 D2-MAC/packet The D2-MAUpacket system was, in part, developed to provide a single baseband interface to other transmission and distribution media. The
41、particular features of the DZMAC/packet system are: - a baseband time division multiplex in which the analogue picture signals are combined with duobinary encoded digital sound, synchronization and data signals: - the capacity of the sounddata multiplex is about 1.5 Mbit/s, equivalent to four high q
42、uality 15 kHz sound channels with near instantaneous 14/10 bit companding (protected by one parity bit per sample). The spare data capacity can be used for other services; - the single baseband representation of the time division multiplex signal is frequency modulated for satellite broadcasting. Th
43、e Federal Republic of Germany and France have adopted the DL-MAC/packet system for operational use of their 12 GHz band broadcasting-satellite services (TV-SAT2 and TDF-1 and TDF-2). _- CCIR RECMN*b50-2 72 Y855232 0537579 337 Rec. 650-2 2.2 B-MAC systems 5 Two closely related implementations of the
44、B-MAC system have been developed for 525 and 625 line applications. Both systems are well suited to use in broadcasting-satellite service applications in the 12 GHz band using either 24 MHz or 27 MHz channelling. The B-MAC signal is a baseband time division multiplex comprising analogue picture sign
45、als combined with a four (or two) level data burst containing digital sound, synchronization and data information. Vision signal coding is performed using the same time compression factors as the C-MAC/packet and D2-MAClpacket systems. The clock frequencies of 625/50 and 525/60 B-MAC systems are the
46、 same multiples of the relevant line scan frequencies to permit use of the same integrated circuit devices for both systems. In the 525 line version the clock frequencies are simply related to the NTSC sub-carrier frequency, facilitating simple transcoding to NTSC. Both B-MAC systems can be configur
47、ed to permit transmission of pictures with 16:9 aspect ratios. The B-MAC systems provide a total data capacity of about 1.6 Mbit/s. This can be used to provide six high quality 15 kHz audio channels using adaptive delta modulation which features error concealment and parity protection (see CCIR spec
48、ial publication “Specifications of Transmission Systems for the Broadcasting-Satellite Service”); alternatively these channels may be configured as 204 kbit/s data channels. A utility data channel makes use of spare capacity in the data multiplex. Included in the B-MAC structure is a conditional acc
49、ess system based on line translational scrambling for video, and data encryption for digital audio. Because of the high degree of commonality between the 625 and 525 line B-MAC systems it will be possible to develop a single receiver capable of receiving either B-MAC system. The B-MAC system provides a single baseband interface to other transmission and distribution media. The 625 line B-MAC system has been adopted in Australia for the Homestead and Community Broadcasting- Satellite Service (HACBSS) which commenced operation in October 1985. The 525 line B-MAC system is under active c
