Appendix E

Purpose of a set-top box for Digital TV

It serves a number of purposes:

• It converts the digital signal into a format that can be viewed on the TV.
• It usually provides the means by which only registered users can access the digital broadcasts – this is known as conditional access.
• It also contains the software to enable the utilisation of interactive services.
• The box may also have an internal modem that can be connected to a telephone line, both for the “return path” for interactive services and for sending user statistics back to the service operator.
• There is also currently limited memory in the box for holding updated versions of the electronic programme guide and other data that might be downloaded into the box. Later generations of set-top boxes are likely to have considerably more memory.