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!
