Description of a D2-HD-MAC/packet chain

The authors describe the D2-HD-MAC/packet chain which constitutes the transmission part of the first experimental HDTV chain in the framework of the HDTV European project Eureka 95. The D2-HD-MAC/packet chain delivers an HD picture compatible with the conventional D2-MAC/packet decoders. The new system requires a 12 MHz baseband to recover the whole HD quality. Nevertheless, it allows the use of a reduced baseband transmission channel down to 5 MHz, compatible with a standard D2-MAC/packet decoder. On the other hand, the digital assistance data (DA), only intended for HDTV picture decoding, can have physical characteristics which are consistent with the ones of the HDTV picture. These considerations lead to a DA channel, inserted in the vertical blanking interval (VBI), at a transmission rate of 20.25 Mbit/s, in a duobinary form