|
C-MAC is the variant approved by the European Broadcasting Union (EBU) for satellite transmissions. The digital information is modulated using 2-4PSK (phase-shift keying), a variation of quadrature PSK where only two of the phaser angles (±90°) are used.〔(【引用サイトリンク】title=MAC (Multiplexed analogue components) in "Analog TV Broadcast Systems" )〕 * The data capacity for C-MAC is 3Mbit/s. * C-MAC data has to be sent to the transmitter separately from the vision. * The transmitter switches between FM (vision) and PSK (sound/data) modulation during each television line period. == C-MAC variants : E-MAC == E-MAC (Extended MAC) is 16:9 version of C-MAC. Originally E-MAC was designed for 15:9 pictures, it later adopted the 16:9 aspect ratio. * In E-MAC all the 4:3 information is transmitted exactly as in C-MAC so that C-MAC receivers are still compatible. * E-MAC hides extra luminance and chrominance information in the field blanking interval and parts of the line blanking interval. * E-MAC has a lower data capacity because luminance is hidden where data would usually be located. * A 'steering' signal is transmitted to indicate to the 16:9 receiver whereabouts the 4:3 picture information. * E-MAC receivers stitch the 4:3 and helper wide-screen data into a seamless 16:9 picture. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「C-MAC」の詳細全文を読む スポンサード リンク
|