Extended television system

摘要

An extended television signal comprises control data for controlling an extended television decoder. The control data comprise first information bits (NB) for conveying information which need not be very reliably decodable immediately upon switching between broadcast channels or when their contents have changed. Each first information bit (NB) is channel-encoded by means of a first DC-free channel code into first channel bits each having a first duration (2 Tc). The control data further comprise second information bits (LB) for conveying information which must be very reliably decodable immediately upon switching between broadcast channels or when their contents have changed. Each second information bit (LB) is channel-encoded by means of a second DC-free channel code into second channel bits which each have a second duration (10 Tc) exceeding the first duration (2 Tc).