Conditional Access - Who's on First?
Conditional access (CA) controls access to digital television
(DTV) services via encrypting programs people watch. It's like
the "umpire" in a ball game that calls your TV signal "safe" and
lets you watch the show you want to see. There are various
conditional access technologies, although they are all based on
ATSC and DVB-compliant CA systems.
Conditional access has three basic elements: broadcast
equipment, set-top box, and security module. The broadcast
equipment generates encrypted programs transmitted to your
television or cell phone. The interactive TV set-top box filters
your signals and passes them on to the security module. The
security module authorizes these programs for decryption. The
programs are decrypted in real time and sent back to the set-top
box for display. It's like at the ball game, the pitcher looks
at the catcher, the catcher at the batter, the batter at the
third base coach and the third base coach at the bat boy. If
every one's set, he pitches the ball.
Subscriber Management System (SMS) - Interactive TV The brains
of Interactive TV are in the Set-top box on top of your TV set.
Your subscriber management system requests the permission to
provide the authorization needed to view the programs. Other
systems acts as a backup system in case your left stranded on
third base..
Subscriber Authorization System (SAS) - Interactive TV The clean
up hitter in your access system responsible, waves your signal
so you can watch the ball game on TV with your kids. There is
also has a security module so you can keep your kids from
watching gulls mate and people from charging their TV shows to
your account. The Interactive TV wizards thought of
everything... they even built a converter to watch digital
signal on your old TV set - the one had since your team won the
World Series twenty five years ago.
Amazing technologies like Interactive TV are costly to develop,
operate and upgrade. With out conditional access, the only way
many people would see their favorite team is out at the ball
park. Also, Believe it or not, many people go to the ball game
and watch replays on cell phones powered by... Hey, I think he
just hit a home run!
NDS is a leading
conditional access solutions provider and Interact
ive TV technology company. For more information, read the
NDS
conditional access white paper.