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. * 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.