Ideographic teletext transmissions

DETAILED DESCRIPTION It is an object of the present invention to provide an ideographic teletext transmission which enables non-spacing attributes to be used without the need for coding extensions, thereby making it suitable for basic (level 1) WST.
According to one aspect of the present invention there is provided an ideographic teletext transmission system in which teletext data is transmitted in the form of a plurality of data packets each packet corresponding to a display row of a teletext data display of said system, each data packet comprising a plurality of data bytes, each data byte corresponding to a display position in the display row corresponding to the data packet, in which each ideogram of the ideographic teletext data to be transmitted by the system is displayed in the space of a plurality of adjacent display rows and in a plurality of adjacent display positions in each of the plurality of said adjacent display rows, characterized in that the data bytes corresponding to the plurality of adjacent display positions in the data packets corresponding to the plurality of the adjacent display rows are used in one data packet thereof to define an ideogram to be displayed and in another data packet thereof to define a display or control attribute or attributes.
In this way, because the ideogram to be displayed is displayed over a plurality of display rows, the data bytes used to define the display attribute are effectively obscured and the display attributes are effectively non-spacing.
Advantageously, each ideogram is displayed in the space of three of the display rows and in two corresponding display positions in each of the three display rows.
In a preferred embodiment, a system is provided in which the data bytes corresponding to the two display positions in the first one of the three data packets which correspond to the three display rows are used to define the ideogram to be displayed.
In carrying out the preferred embodiment, the data bytes corresponding to the two display positions in the second one of the three data packets which correspond to the three display rows are used to redefine the ideogram to be displayed, one or more of the data bytes corresponding to the two display positions in the third one of the three data packets which correspond to the three display rows being used to define the display attribute or attributes