. ▁ ▁D 2 - MA C ▁uses ▁half ▁the ▁data ▁rate ▁of ▁D - MA C ▁▁ ▁D 2 - MA C ▁has ▁a ▁reduced ▁vision ▁band width , ▁about ▁ 1 / 2 ▁that ▁of ▁D - MA C . ▁ ▁D 2 - MA C ▁retain s ▁most ▁of ▁the ▁quality ▁of ▁a ▁D - MA C ▁signal — but ▁cons umes ▁only ▁ 5   M Hz ▁of ▁band width . ▁ ▁Techn ical ▁details ▁ ▁MAC ▁transm its ▁l umin ance ▁and ▁chrom in ance ▁data ▁separately ▁in ▁time ▁rather ▁than ▁separately ▁in ▁frequency ▁( as ▁other ▁analog ▁television ▁formats ▁do , ▁such ▁as ▁composite ▁video ). ▁ ▁Audio ▁and ▁Sc r amb ling ▁( select ive ▁access ) ▁ ▁Audio , ▁in ▁a ▁format ▁similar ▁to ▁N IC AM ▁was ▁transm itted ▁digit ally ▁rather ▁than ▁as ▁an ▁FM ▁sub - car rier . ▁ ▁The ▁MAC ▁standard ▁included ▁a ▁standard ▁scr amb ling ▁system , ▁Euro C rypt , ▁a ▁prec ursor ▁to ▁the ▁standard ▁D VB - C SA ▁encryption ▁system . ▁ ▁History ▁and ▁politics ▁MAC ▁was ▁developed ▁by ▁the ▁UK ' s ▁Independent ▁Broadcast ing ▁Author ity ▁( I BA ) ▁and ▁in ▁ 1 9 8 2 ▁was ▁adopted ▁as ▁the ▁transmission ▁format ▁for ▁the ▁UK ' s ▁forth coming ▁direct ▁broadcast ▁satellite ▁( DB S ) ▁television ▁services ▁( event ually ▁provided ▁by ▁British ▁Sat ellite ▁Broadcast ing ). ▁The ▁following ▁year ▁MAC ▁was ▁adopted ▁by ▁the ▁European ▁Broadcast ing ▁Union