| 摘要 |
Interactive television system with interavtivity data transmission together with the TV signal, exploiting the unused lines of a TV signal, and a decoder connected with each subscriber set to process said interactivity data and visualize in overlap on the screen signals or windows obtained from these data. The interactive data (10) is set up by elementary data units or messages (M) structured in a hierarchical way, each one set up by a first header portion (H) and by a second control portion (C) containing data (CN) on the number of controls present in the message and at least one control (CM) of Interactive Activity. <IMAGE> |
