1、CCIR RECMN*80b 92 4855232 0520LL8 Ob5 Rec. 806 139 RECOMMENDATION 806* COMMON CHANNEL RASTER FOR THE DISTRIBUTION OF D-MAC, D2-MAC AND HD-MAC SIGNALS IN COLLECTIVE ANTENNA AND CABLE DISTRIBUTION SYSTEMS (Question 68/1 i) ( 1992) The CCIR, considering a) that Recommendation 650 in Annex 1 recommends
2、the use of multiplex analogue components systems D-MAC/packet and DZMAC/packet systems for satellite emission of TV, and gives the corresponding specifications; b) that Recommendation 787 recommends the HD-MAC/packet system for satellite emission of MACpacket- based compatible HDTV, and gives the co
3、rresponding specifications; c) that there is an urgent need to provide means of distributing the TV signals received from these emissions in cable and community antenna systems; d hat VSBIAM versions of the D-, D2- and HD-MAC systems intended for such distribution are specified internationally by, f
4、or example, the EBU in Tech. hblication 3258; e) that the RF characteristics of MAC AM-VSB cable receivers have been specified internationally in, for example, the European standard EN 50080; 0 that VSB/AM D- and HD-MAC are optimized for distribution in 12 MHz channels; g) that VSB/AM D2-MAC is adap
5、ted for distribution in channels with a bandwidth of 8 MHz; h) that VSB/AM D2-MAC signais can also be conveyed with full quality in a 12 MHz channel; ,., j) that a common channel raster would be of great advantage to facilitate the transition from MAC/packets to HD-M AC/packets; k) that so far few a
6、dministrations have implemented the use of the band 300-470 MHz (also known as hyperband) for cable systems, noting that DZMAC terrestrial narrow-band emission is under study, recommends that, to the extent practicable, administrations or organizations wishing to have a common channel raster in their collective antenna and cable distribution systems for HD-MAC, D-MAC or full-quality D2-MAC VSB/AM signals in the band from 300-470 MHz should use a 12 MHz channel raster. * This Recommendation should be brought to the attention of the EC aod the CMT.
