SCRAMBLING AND CONDITIONAL ACCESS SYSTEMS:
Scrambling: It is to suppress the sync signals at transmitting end The picture without H and V sync cannot lock into steady picture seen as rolling picture and diamond bars. For descrambling, a pilot carrier containing the sync timing information is transmitted on separate carrier.
Another method with great security and complexity is baseband scrambling, the scrambled coded lines are decoded and it requires demodulation process.
Scrambling is possible by digital processing of video and audio and introducing complex encryption and smart keyboard for controlled access.
Now Addressable converters: includes tunable converters and address recognization
circuitry which is controlled by computer so specific channels are turned OFF or ON to subscriber.
Equipment compatibity access, support, user system interface, telephone communication module. The techniques used are scramblers and injectors upstream and descrambler modules.In cable and satellite systems, 3 different operational are projected
Access to a given channel for fixed duration
Pay per view with preselected choice of channel
Pay per view without preselction.