Digital Addressable System is a service in which TV channels are sent over network in digital and encrypted form with addressable feature. Only authorized users can receive channels using a Set-Top-Box (STB) and TV set. The authorization is given by the service provider. This system is able to carry large number of TV channels, radio services and other value added services. In this system, the consumers can choose channels/ services of their choice and pay only for the channels/services that they choose.

The Multi-System Operator (MSO) and its linked local cable operators (LCOs), DTH (Direct to Home), HITS (Headend in the Sky), IPTV are the service providers in DAS.

The earlier cable TV system was predominately analog in nature. In case of analog cable TV system, the TV channels were sent in analog and unencrypted form. The analog cable TV system could carry up to 80-100 TV channels only. In the analog system, the consumers did not have an option to choose channels/services of their choice and pay accordingly, rather they had to pay for the entire bouquet of channels offered by the cable operator.

On the other hand, the capacity of a DAS is much higher than the analog cable TV system. A consumer under DAS is able to choose channels/services of his choice and pay accordingly. A Set-Top-Box (STB) is required for receiving the channels in DAS.

As per Cable Television (Networks) Regulation Act, 1995, it is obligatory for every cable operator to transmit or re-transmit programmes of any channel in an encrypted form through digital addressable system only.

Both are digital addressable systems. In DTH service, TV channels are directly received by the consumer from the satellite using small dish antennas located at the Customer’s premises. In DAS enabled cable TV, the transmission is made through the cable network.

The DAS offers following benefits to the consumer. 

• Consumer gets better signal quality for all the channels.
•  Consumer gets more choice of channels. DAS supports HD and 3D channels.
•  Consumers can choose the channels on a-la-carte (individual) basis and pay only for the channels chosen. 
• DAS can offer value added services such as triple play with broadband, movie on demand etc. 
• Electronic Programme Guide (EPG) can be provided in DAS which makes it easy for the consumer to select a particular channel or service in a simple and user-friendly manner. These features, amongst the others, provide a much improved viewing experience to the consumers.

As mentioned above, as per Cable Television (Networks) Regulation Act, 1995, it is obligatory for every cable operator to transmit or re-transmit programmes of any channel in an encrypted form through digital addressable system only.

For getting the services in DAS, an additional piece of equipment called SetTop Box (STB) is required along with TV set. This set top box will facilitate the consumer to access the encrypted digital television signal carried over DAS.

“Set top box” (STB) is a device, which is connected to a television set at the consumer premises and which allows a consumer to view encrypted channels of her choice. The basic function of the set top box is to decrypt the channels and to convert the digital signals into analog mode for viewing on television sets. A smart card or viewing card is a part of set top box which allow only those channels to be viewed which are subscribed by the consumer and authorized by the service provider.

The TV channels carried in DAS cannot be received without STB. The STB can be a stand-alone unit or TV sets can have STB functions integrated into it

Yes. DTH and DAS- Cable TV are two independent platforms. One can have DTH as well as cable TV.