Teletext System Theory And Applied Research

This thasis introduces systematicalIy the basic theory and relevant technology of TeletextSystem. Its emphasis is placed on illustrating CCST protocol over data package, ana1yzing CCSTchanncl properties, and comparing the merits and demcrits of the several exishng schemes. Aftergiving thc explicit research about the grapllic c1laracter systcm and the coding character System, thepaper ana1yzes the feasibility of the graphic cl1aracter whicl1 is not used popuIarly now On basis ofthe former mentioued, the JPEG aIgoritlun is disscrted and pertinent conclusions are proPOsed fl. The graphic character should be thc main trend in phOtographic tolecommunicahonbecause of its good quality and high cIDrity for picture, and it is alBo useful fOr CCSTtvhicll bolongs to still photograpl1ic telccommunication.2. Digital TV, which is the present development tendency, provides a veryconvenient condition and also can do somc goods to the Teletext system th8t will shiftlo graphic characteL3. JPEG algorithm, as tIle encoding standards for still photographs, has adopted theDCT transfOrm and Z scanning. So JPEG can and should be the theoretical basis ofCCST gtaphic character syStem.1n thc end of the paPer, some works are put on cxplaining and Iooking fOrward to theprosPCrous ftlture of TeIctcxt.