GB12047一89按节日数编码图4b,=0,b,一奇偶校验码5.2.2图像通道码(VCH)(如图5)8bitsVCH-video channelb.b b.by bo by按节H数编码图5】顿存储存储状态码b一气0场存储D,一奇偶校验码5.2.3声音通道码(ACH码)（如图6）8bitsACH-audio channel按节日数编码图6(1(57.5kH取样，42路声音)声音状态码b,:b:一奇偶校验码,0(115kHz取样，21路声音)5.3纠错码(N,E)BEST码N一每行总码数，N=272E-一每行有效码数，E=190BEST-burst and random error-correcting system for teletext6数字信号（声音和控制码为数字信号）6.1码型2值，NRZ,同步6.2频谱余弦滚降（滚降系数0.73）6.3时钟码率6.9375Mb/s(6.9375MHz=444f)6.4数字同步码(DS码)6.4.1时钟码16bits(0010101010101010)6.4.2状态识别码随机节目顺序4bits(OFV/AO)固定节目顺序4bits(OFV/AN)F一帧同步码V/A一图像帧与声音帧识别码3
