Teletext ¿ enhancing the basic system

The UK teletext system specification includes provision for future developments. This paper indicates how the addressing structure may be used to allow selection from a very large number of pages either individually or by classification. Up to 64 totally independent data channels can also be provided. Various techniques for extending the character repertoire are described, depending on whether the extra characters are predefined, postdefined or dynamically redefined. Methods of increasing the security against errors are presented. It is suggested that within the framework of the existing teletext standard it is possible to work towards a system capable of giving a short sequence of colour pictures, whose quality is limited only by the television display itself. Any other requirements for the broadcasting of information for display on the television screen can then be treated as suboptions of such a system.