ITU-R - International Telecommunication Union/ITU Radiocommunication Sector
Scope
Introduction Thee study and development of systems and services of data broadcasting are active in various areas such as the television and sound channels in terrestrial and satellite broadcasting. In order to ease standardization of data broadcasting systems and to facilitate smooth evolution of data broadcasting services in the future@ the development of a common reference model for data broadcasting is necessary. In particular@ the use of such a reference model would facilitate the description and introduction of integrated services digital broadcasting (ISDB) which could include teletext@ still pictures@ audio signals@ high fidelity audio@ facsimile@ data and other type of information. In the CCIR Recommendation 553 the teletext systems are described having an alignment with the ISO layer model for open systems architecture. This layered model could also be the basis for the development of a common reference model for data broadcasting whereby the four lower layers describe the data broadcasting system and the three upper layers generally characterize the service.