Digital television terrestrial transmisson has to deal with various reception conditions: a plug-free TV set receives much lower a signal than a roof-top antenna. It is hence interesting to provide a signal that conveys two types of information:- a "basic" picture for portable receivers; this information must be transmitted most reliably.- additional information to be added to the basic picture in order to get a higher definition picture; this less protected information can be decoded by fixed receivers only.This implies multi-protection - or hierarchical - channel coding, including very efficient codes to protect the basic picture. This article describes a hierarchical channel coding and modulation scheme that, together with a new family of binary codes, is believed to allow the design of good hierarchical transmission systems.
展开▼
