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.