C-MAC

C-MAC is the television technology variant approved by the European Broadcasting Union (EBU) for satellite transmissions.^[1][2] 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.^[3]

• The data capacity for C-MAC is 3 Mbit/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.

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.

MAC transmits luminance and chrominance data separately in time rather than separately in frequency (as other analog television formats do, such as composite video).

Audio and Scrambling (selective access)

• Audio, in a format similar to NICAM was transmitted digitally rather than as an FM sub-carrier.
• The MAC standard included a standard scrambling system, Euro-Crypt, a precursor to the standard DVB-CSA encryption system.

TV transmission systems

• Analog high-definition television systems
• DVB-S
• DVB-T
• Multiplexed Analogue Components
• PAL
• SECAM